Wednesday, November 30, 2011

Boiler Control System

Boiler Control System
The boiler control panel provides operation, control and interlock devices
required for the safe running of the boiler. This control panel directs the
performance of all functions required for automatic operation of the boiler and
provides a central control point for manual operation. The control system also
features a network of alarms which give warning if an abnormality occurs
during boiler operation.
In the event of a serious abnormality occurring, which would make it unsafe
for the boiler to continue in operation, the boiler automatic control system
shuts down the boiler in an emergency mode, by immediately shutting down
the fuel oil supply to the boiler.
Control Panels
ECR Console Remote Indication Panel
This indication panel is installed in the engine control room and it mimics the
monitoring systems and main controls found at the boiler and boiler side
control panel.
The ECR console has the following items:
Drum level indicator
Steam drum pressure indicator
Smoke indicator
Emergency stop switch
Burner run lamp
Lamp test switch
Boiler Side Boiler Control Panel
This control panel is installed at the boiler side. It contains the system power
supply unit, the sequence control for operation of the burner, the automatic
boiler controller and various necessary relay units.
The following alarms are mounted on the control panel :
Electrical AC power source failure
Burner start sequencer inactive
Manual trip
FD fan trip
Pilot pump abnormal
Drum level low-low
Atomising pressure low
Ignition fail
Flame fail
Flame eye abnormal
Burner piston valve abnormal
FO pressure low-low
Control air pressure low
Burner Control System
The boiler control panel (BCP) operates in a number of functions associated
with the boiler including the boiler management system (BMS), automatic
combustion control (ACC), and feedwater control (FWC). There are two
boilers and they are controlled on a master/slave basis with one of the boilers
being designated the master by the control system and the other the slave.
Under normal circumstances the master boiler would operate to supply the
ship's steam requirements but if it cannot meet demand the slave boiler is
started and comes under the control of the boiler control system. The boilers
may also operate in conjunction with the economiser; usually this means that
the economiser is operating at sea and one of the boilers is selected to act as
the water supplier and the steam collector for the economiser. The boiler
would operate if the economiser could not maintain steam pressure for any
reason.
The boiler control system controls the remote, manual and automatic
operations of one single-throat burner which is provided in the roof of the
boiler. This unit contains a programmable sequence control, which operates the
furnace purge, pilot burner and the automatic operation of the burner piston
valve. This is done by linking up with the boiler protective system and the
ACC. In addition, it transmits the automatic adjustment commands of
combustion air quantity and fuel oil quantity to the ACC for the start/stop of
the burner. Combustion control is at the heart of boiler operation because if
anything goes wrong with the boiler, its water supply or the combustion
system, fuel must be shut-off and that will prevent any problem becoming
more severe.
There are three boiler operating modes, one is the 18k mode (steam supply at
18kg-cm2), the second is the 7k mode (steam supply at 7kg/cm2) and the third
is the IGS mode (inert gas system in operation).
In port during cargo discharge the 18k mode would be selected but, at sea only
the 7k mode would normally be required with the oil fired boiler installation
providing support for the waste heat economiser. In some cases, intermittent
oil firing on the boiler may be needed to maintain steam pressure and the boiler
control panel would organise that. Selection of 18k mode or 7k mode is
executed by the changeover switch and selection of a particular mode auto-
matically changes the set point on the pressure indicator control (PIC).
Procedure for the Preparation of Boiler Control System
a) Turn on the power switches of the boiler control panel.
b) Check the action of each pilot lamp and buzzer using the buzzer
and lamp test switch on the control panel.
c) Supply air to all the control devices.
d) Reset the boiler interlock alarm.
e) Check that all alarm lamps are out.
Operating Method
There are three burner operating modes, AUTO (Automatic), MAN (Manual)
and HARD MAN (Hard Manual) mode. The burner is usually operated in the
AUTO mode and the MAN modes are only used in an emergency when the
AUTO mode cannot function. The HARD MAN mode allows for reposition-
ing of the burner switches and the MAN mode is for operating on manual.
Selection of Operating Modes
HARD MAN Mode
When operating in this mode, the operator must always be at the boiler and
able to monitor the situation and provide manual intervention at the control.
The following interlocks are effective:
Drum water level low-low
Flame monitor (pilot burner and main burner)
Operating Procedure
a) Check that the boiler and burner are in operating condition.
b) Start the fuel oil pump and the forced draught fan in the MAN
mode.
c) Turn the burner switch from the OFF position to the HARD MAN
position.
d) Set the fuel pressure controller and the air controller to the MAN
mode.
e) Purge the furnace. To do this the air controller should be manually
operated and the forced draught fan inlet vane should be fully
opened. The furnace must be purged for at least 3 minutes.
f) Check that the fuel temperature is within the required range.
g) Manually operate the air controller and the fuel oil pressure
controller and set the forced draught fan inlet vane and the fuel oil
control valve to the ignition open position.
h) Open the sub-door for the HARD MAN operating switches. Set
the pilot burner switch to the MANU ON position and ignite the
pilot burner. If the pilot burner has not ignited after 15 seconds the
pilot burner switch should be reset to AUTO and the process
started over again from item e) above, 'Purge the furnace'.
i) With the pilot burner burning correctly the main burner is ignited.
The fuel oil valve switch is set to MANU ON and the main burner
should ignite. If the main burner does not ignite after a period of
10 seconds the fuel oil valve switch should be reset to AUTO and
the procedure started over again from item 'e', above 'Purge the
furnace'.
j) With the main burner operating correctly the pilot burner switch
is reset to AUTO.
(Note ! When extinguishing the main burner the fuel oil valve switch must be
returned to AUTO.)
When burner purging is required, the burner purging switch must be used and
this must be set to MANU ON.
Fuel Oil Temperature Bypass
The fuel oil temperature by-pass switch is inside the sub-door. In this bypass
mode the starting interlock for fuel oil temperature low alarm is bypassed. It is
used when starting the boiler in the cold condition when steam is unavailable
for heating. When using 'A' grade heavy oil, the switch is set to BYPASS.
AUTO Mode
This is the mode which will normally be used. All operations, including the
commands for ignition and extinction, are operated automatically.
a) Set the fuel oil pumps, the forced draught fan and the controllers
to the AUTO mode.
b) Turn the burner switch from the OFF to the AUTO position.
When stopping this switch must be returned to the OFF position.
The following sequence of events must be accomplished for main burner
ignition.
a) When the burner switch is moved to the AUTO position the
program timer starts.
b) After a delay of 5 seconds the forced draught fan starts and the
atomising steam valve opens.
c) After a further 20 seconds the forced draught inlet vane starts to
move to the fully open position in order to purge the furnace. It
takes approximately 30 seconds to become fully open.
d) The purge timer (2P) commences when the burner switch is
moved to the AUTO position and the time set on this timer is 60
seconds. After the 60 seconds has elapsed, the forced draught fan
inlet vane starts closing gradually to the ignition position. At this
point the furnace will have been effectively purged.
e) The pilot burner is ignited 35 seconds after item 'd'.
f) When the flame of the pilot burner is detected by the flame eyes,
the electrical igniter stops sparking.
g) The main fuel oil valve opens 5 seconds after the pilot burner is
ignited.
h) The pilot burner is extinguished 15 seconds after it has been
ignited (item 'e').
i) The program timer stops at the lock-in position (graduation 85)
5 seconds after the pilot burner is extinguished.
j) If there is an ignition failure or a flame failure the burner control
goes into an extinction sequence.
k) The extinction sequence commences when the burner CUT
INTERLOCKS have actuated (following item 'j' above) or if the
burner switch is turned from the AUTO to the OFF position.
1) The program timer starts from the lock-in position.
m) The pilot burner is ignited 2 seconds after item 1) above.
n) The burner purge valve opens and the burner is purged for about
6 seconds. The burner is purged when the interlock is normal and
the pilot burner lights up.
o) The post purge period commences and the forced draught fan inlet
vane starts to open to its fully open position when the burner
completes it purge cycle.
p) After the set time (60 seconds) on the post-purge timer is
completed, the forced draught fan inlet vane starts closing to the
ignition position which takes about 30 seconds.
q) The forced draught fan stops after 30 minutes.
(Note ! If flame failure occurs during normal operation, it is important that the
cause of the failure is investigated before any attempt is made to restart the
boiler.)
Automatic Combustion Control
This system automatically regulates the fuel and air supply to the furnace in
order to maintain a preset steam pressure in the boiler. Regulation of the fuel
supply is accomplished by means of the air operated fuel control valve whilst
the air supply is controlled by means of the inlet vane of the forced draught fan.
Fuel supply is automatically cut off in the event of forced draught fan failure
or due to high or low water level in the boiler drum. The ACC system is
electro-pneumatically operated.
The automatic combustion control (ACC) system employed is of
a fuel oil pressure/air pressure measuring type.
The ACC is held at predetermined ignition position until the
burner is ignited.
After the burner is ignited the combustion rate is fixed at the
ignition position until the boiler pressure reaches the predeter-
mined pressure of 5 kg.cm2. This period is called 'steaming'.
When the steaming period is completed, the ACC system goes to
AUTO RUNNING and the combustion rate can be adjusted by the
system.
During the steaming period the combustion rate can be changed
by operating the fuel oil pressure controller in the MANU mode.
The air/fuel ratio can be changed by up to + 20% by altering the
air ratio dial. This dial would normally be set at the position 1.
MAN Mode.
This mode is selected to allow for manual starting of the boiler in order to see
that all stages are completed correctly. It is used when the boiler would
normally be operated automatically as a means of checking the start-up
procedure. The procedure is the same as for HARD MAN start but no switches
behind the HARD MAN sub-door are changed.
Feedwater Control.
This controller is of the two element type; both have proportional and integral
(P+I) control. It measures the steam flow rate and also the water level in the
boiler and adjusts the feedwater supply in line with changes in these values.
The P+I operation is performed when comparing signals from two separate
systems. One of the signals is generated by the difference between the water
level set and that detected in the steam drum of the boiler. The other is from
comparison between the detected steam flow rate from a steam flow
transmitter and the operating signal to the feedwater control valve. In ECON
(economiser) mode the water level change due to the ship's rolling and
pitching is accounted for by consideration of the moving average level in the
steam drum.

Master-Slave System.
The two boilers are independent units, but the control system is designed so
that they operate as a dedicated pair with one being the master boiler and the
other the slave. This means that the master boiler supplies the ship's steam
requirements until the demand exceeds its capacity and then the slave boiler
commences operation. The slave boiler will have been kept in a state of
readiness for such a situation and would have been at the same temperature as
the master boiler in order to avoid delays in wanning through.
a) The master boiler is controlled by actuation of the ON/OFF
switch and the pressure indicator so that the steam pressure of an
individual boiler will retain its set point. The actuation is executed
in the same way as the normal one boiler system.
b) When steam demand on the master boiler exceeds 80% of its
capacity, the slave boiler is switched on. It is switched off when
the steam demand is 30% of the total capacity of the two boilers.
The combustion rate for the slave boiler is the same as for the
master boiler, as the master boiler is exercising overall control.
c) In addition to the ON/OFF actuation of the slave boiler from the
master-slave controller, the slave boiler can also perform its own
ON-OFF actuation of combustion due to the pressure in the boiler.
The slave boiler retains overriding control of combustion due to
the pressure within the boiler and that pressure is the slave
boiler's own set pressure and is independent of the pressure
setting for the master boiler.
d) The low limiter actuates for 15 minutes after the slave boiler has
been started in order to prevent the ON/OFF hunting phenomenon
at the slave boiler.
e) The pressure in the slave boiler needs to exceed 11 kg-cm2 in
order for the master-slave configuration to operate.
f) In addition to the master-slave operation it is possible to select the
PARA mode where both boilers can be turned off independently.
In this case the boilers would be operating together each under its
own independent control and not as a master-slave pair.
Safety and Control System.
Incorporated in the safety and control system are operating functions, or sub-
systems, which react automatically to a change in condition outside of the pre-
set range. Failure of most sub-systems produces a visual alarm on the main
control panel and may also produce an audible alarm. In the majority of cases,
failure of a sub-system requires manual resetting of the cut-out before the sub-
system can be restarted. This provides protection for personnel on the ship and
for the boiler installation, as the reason for a sub-system failure can involve
more than that particular sub-system.


Inert Gas Topping-up Mode.
The inert gas system (IGS) topping-up mode is used in order to allow the boiler
to operate on a minimum load so that the IGS may function correctly. A
minimum boiler load of 25% is required so that the flue gases will contain no
more than 5% oxygen; the flue gas flow at minimum rate will be 10,300m3/h
at a temperature of 5°C. The following items will be interlocked, and hence not
operable, in this mode.
Boiler minimum load is limited to 30% or greater if dumping of steam
is operating.
The IGS running lamp is illuminated
Bypass of the FO burner auto stop
Steam supply valve to soot blowers is interlocked to FULL CLOSE

Boiler Alarm and Trips.
Description.

Emergency Mode.
The boilers may be operated in emergency mode when the burner sequencer is
inoperative.
a) Start the FD fan then fully open the FD fan inlet vane and perform
the furnace purge for 3 minutes.
b) Ensure that the FO temperature is at the specified level,
equivalent to 15cSt.
c) Set the FO control valve and FD fan inlet at IGNITION OPEN
positions respectively.
d) Light off the pilot burner with care and do not exceed 15 seconds
ignition time.


e) Ensure that the pilot burner has ignited and open the FO piston
valve to allow oil to the main burner.
f) Do not keep the FO piston valve open for longer than 10 seconds.
g) If the main burner fails to ignite, the furnace must be purged prior
to a repeat attempt at ignition.
(Note ! During an emergency operation a careful watch must be kept on the
boiler at all times.)
FO Temperature Bypass
When burning HFO during emergency mode this bypass must be operated.
Steam press. 7kg-cm2 mode (start-stop) 6.5 kg-cm2 - 9.5 kg-cm2
Slave boiler start enabled 11.0 kg-cm2
Slave boiler (start-stop) 12.6 kg-cm2 - 4.6 kg-cm2

 
 
Sootblowers
Auxiliary Boiler Sootblowers
No. of sets :

Two fitted to each boiler

Sootblowing has to be carried out at regular intervals to ensure that the heat
transfer surfaces are kept clear of deposits, as these retard heat transfer and can
constitute a fire hazard.
Two sootblowers are fitted to each boiler and should be operated daily when
boilers are in use, bearing in mind the position of the vessel and any local
legislation concerning pollution and clean air. They should be operated when
leaving port prior to shutting down the boiler. The sootblowers are fitted with
an air purge connection, the air being supplied from the discharge of the forced
draught fan. This purge or sealing air keeps the nozzles clear during boiler
operation and provides a seal at the air sealed wall boxes to prevent the escape
of boiler exhaust gas into the machinery space. Non-return valves prevent
steam from entering the air lines.
The sootblowers are only to be operated when the available steam pressure
exceeds 8 kg/cm2. An isolating valve, located in the steam line between the
sootblower steam supply valve (T25V) and the sootblower distribution line,
will only be opened by its associated pressure switch if the steam pressure
exceeds 8 kg/cm2.
Before operation, request permission from the bridge and notify the bridge on
completion.
Procedure for the Operation of the Auxiliary Boiler Sootblowers
a) The boiler should be on a minimum of 50% of full load and the
forced draught fan operating at a high rate during the sootblowing
period. The steam pressure must exceed 8 kg/cm2.
b) With the drain open slightly (No.l boiler valve T29V and No.2
boiler valve T28V), open the steam stop valve (T25V) to the
sootblower header.
c) When the pipeline is warmed sufficiently, shut the drain valve and
open the stop valve fully.
d) Operate the sootblower by turning the handwheel in a clockwise
direction. The sootblower cleans the boiler heating surfaces by
impacting steam from a row of nozzles set along the length of the
sootblower element. A cam and trigger arrangement, incorporat-
ed in the sootblower head, regulates the steam arc issuing from
the nozzles as the sootblower element rotates. This ensures
optimum cleaning of the tubes.
e) Operate the top sootblower first, followed by the bottom one. The
top blower should be operated again. The system is then shut
down and the drain valve opened.
WARNING
Do not operate the auxiliary boiler sootblowers during inert gas operations.

 
 

Emergency Operation and Putting Boiler out of Service

Emergency Operation
Low Water Level
A low water level, 140mm or more below the normal working level, will activate the visual and audible alarms (illumination of the alarm lamp on the control panel and sounding of the alarm buzzer).
Should the water level fall to 250mm or more below the normal working level, the fuel oil emergency trip valve will close, shutting off fuel from the boiler.
The feedwater valve and steam stop valve should be fully closed, the burner shut down completely and the forced draught fan stopped after purging the furnace.
Never attempt to supply feedwater to the boiler until the boiler has cooled sufficiently, as there is a danger of bringing comparatively cold feed into contact with hot surfaces.

When the boiler water level has been restored the boiler may be flashed up using the normal procedure.
Flame Failure
In case of flame failure, close the oil inlet valve and reduce air pressure to prevent over cooling the furnace.
Purge the furnace thoroughly before relighting the burner.
Always use the pilot burner for ignition, never attempt to relight the burner from the hot furnace refractory.
Evaporating Tube Failure
Serious tube failure where water level cannot be maintained.
a)  Shut off the oil supply to the boiler and if the tube failure results from low boiler water level, shut off the feed supply, close the feedwater valve and steam stop valve.
b)  If the tube failure results from a cause other than low water level, the fuel supply should be shut off but the feedwater supply should
be maintained in order to assist in the cooling down process.
When the boiler has cooled sufficiently, close the feed valve and steam stop valve and open the steam drum vent.
c)  In either case of tube failure, maintain the forced draught fan so that the air draft assists in carrying away the escaping steam.
Care must be taken to avoid damage to the refractory by an excessive air supply.
d)  Do not blow down the boiler unless the tube failure is so severe that personnel could be endangered.
When the boiler has cooled, the blowdown may be used to empty the boiler.
e)  When the boiler has cooled enough, an inspection should be carried out to assess the situation and carry out necessary repairs.
f)   If tube failure is not serious and the water level can readily be maintained, the boiler can be shut down in the normal manner.

The forced draft air supply should be maintained to carry away vapours generated by the leaking water and the water level
maintained during the cooling down period.
When boiler pressure has fallen to 2 kg/cm2, the steam drum vent valve boiler may be opened and the boiler blown down.
Putting the Boiler Out of Service
When putting a boiler out of service, the wet lay-up method is preferable, as it requires less preparation and it can be quickly returned to service.
These steps are taken if the ship is to be taken out of service for some time and are not part of normal operational routine.
Wet Lay-up
When the boiler is in the cooling down process following shutdown, appropriate quantities of boiler chemicals should be injected into the drum
using the boiler chemical injection device.
To ensure adequate protection of the boiler, follow the guidelines given by the chemical supplier.
The quantity of the chemicals required will depend upon the condition of the boiler water and a water test should be carried out prior to shutting down.
After dosing the boiler water should register pH of 12, (alkalinity 300 to 400 ppm) phosphoric acid about 50 ppm, and sodium sulphite 80 to 100 ppm.
The high alkalinity will ensure adequate protection of the boiler.
When returning the boiler to service the chemical concentrations should be returned to normal levels and this means blowing down the boiler and filling with untreated make-up feed.
a)  When the pressure is approaching atmospheric pressure, open the steam drum air vent valve.
b)  When the pressure is off the boiler, supply distilled water until it issues from the vent valve, then close the vent valve.
c)  Put a hydrostatic pressure of 3.5 to 5kg/cm2 on the boiler.
Hold this pressure until the boiler has cooled to ambient temperature.
Bleed the boiler using the vent valve to be sure all the air is out.

Maintain a hydrostatic pressure of 2 to 3.5 kg/cm2 on the boiler.
Take a periodic boiler water sample and replenish any depleted chemicals.

Maintaining Boiler in Warm Condition
At sea, with one boiler being circulated through the waste heat economiser, the standby boiler should be maintained in a warm condition by supplying steam to the heating element in the bottom drum.
This is done by closing the heating coil drain valve and opening the inlet and outlet valves.
The boiler pressure should be maintained at 0.5 kg/cm2 or above.
When the heating element is not in use, the inlet/outlet valves are closed and the drain left open.
In port with the economiser shut down, the standby boiler is maintained at 2kg/cm2 or above by switching the burner on and off. Do not use the bottom drum heater.
Dry Lay-up
This should only be undertaken if a wet lay-up cannot be performed.
a)  Whilst the boiler remains warm, drain it of all water and ensure that all headers are dry.
b)  Remove the end piece of the waterwall lower header to check that no water remains.
c)  Provide some dry heat, electric heaters preferably, in the furnace to promote internal drying.
d)  When the boiler is completely dry, put some quick lime or calcium chloride in a shallow dish for placement in the drum and
header then close the end plate and manhole doors.
Check the moisture absorbent chemicals every week initially and replenish as required.
e) Cover the funnel outlet and close the air inlet to the furnace.

Marine Boiler Operation Construction


Boilers and Steam Systems
General Description
The steam generating plant consists of two auxiliary boilers and one exhaust
gas economises Steam is required at sea for fuel, domestic water and cargo
slop tank heating purposes. In port steam is used additionally for driving the
power turbines of the cargo pumps and No. 1 water ballast pump. The steam
demand of the plant, in port, is served by the boilers. At sea, steam demand is
met by circulating boiler water from one of the auxiliary boilers through the
exhaust gas economiser, by one of the boiler water circulating pumps. The
auxiliary boiler acts as a receiver for the steam generated by the economiser.
The economiser is arranged in the main engine exhaust gas uptake to take
waste heat from the main engine exhaust. An auxiliary boiler may be required
at sea in low temperature areas, as well as reduced power operation of the main
engine, such as during manoeuvring or slow steaming on passage when there
will be insufficient waste heat to generate the required steam.
Auxiliary Boiler
No. of sets: 2
Maker: Hyundai Heavy Industries Ltd
Model: HMT-50
Type: Top fired rectangular water tube marine boiler
Evaporation: 50,000 kg/h
Steam Condition: 18 kg/cm2 saturated steam.
Fuel Oil: HFO up to 700 cSt at 50°C
Safety Valve Setting: 20 kg/cm2
Fuel Oil Consumption: 3,850 kg/h at 100% evaporation
Boiler Associated Equipment
Equipment
Combustion Control Electronic/Air Operated
Feedwater Regulator Electronic/Air Operated
Remote Water Level Gauge
Drum Level Safety System
Steam Jet Oil Burner
Water Level Gauge - Reflex Type
Safety Valve - Full Bore Type
Chemical Dosing Unit
FDFan
FO Pump
FO Heater
Description
General Construction
The boiler is of the two drum rectangular type, with a membrane furnace water
wall connecting steam and water drums.
The furnace consists of gas-tight membrane walls, the downcomer pipes are located outside of the furnace.
The fuel burner unit and associated combustion air inlet, is located in the roof of the furnace with the burner firing downwards using a steam assisted pressure jet burner.
At the furnace bottom, a refractory protects the furnace bottom from the combustion flame.
Combustion gases flow downwards and through the lower part of the division tube wall and the lower section of the generating tube
bank which connect the steam and water drums.
The gases then flow upwards on a return path through the upper part of the generating tube bank to the flue gas box at the top of the boiler.
Radiant heat generates steam in the membrane furnace water wall tubes.
The membrane wall has access doors to allow for furnace inspection and cleaning.
The boiler structure is rigid enough to withstand rolling, pitching and shock loading of the ship operating in a seaway.
The boiler is supported at the water drum and the water wall lower headers, and there are no rigid connections at any other points in order to allow for thermal expansion.
Furnace
Closely spaced water wall tubes of 76.2mm outside diameter, form the membrane walls at the side, roof, except for burner opening, rear, and front of the furnace.
This construction is in order to increase the radiant heat absorption in the furnace and to make it strong enough to withstand vibration.
The furnace is made completely gas-tight by the welded water wall construction.
Situated at the top and bottom of the front and rear walls are water wall headers.
Water enters the bottom headers and rises through the tubes to the top headers due to natural convection.
As the water rises, it is heated until its saturation temperature is reached and it then begins evaporating.
This water- steam mixture is passed to the steam drum via the top headers.
Front and rear water wall tubes connect to steam and water headers at the top and bottom respectively; one end of each top header connects with the steam drum and one end of each bottom header connects with the water drum.
The roof, side and bottom water wall tubes are directly connected to the water and steam drums.
The steam generating bank of tubes, connecting steam and water drums, is located within the furnace.
Boiler Casing
As the furnace of the boiler is made completely gas-tight by the adoption of welded membrane water wall construction, no casing or refractory is required to contain the combustion gases.
Mineral wool insulation is provided on the outer surface of the furnace water walls and this is covered by corrugated galvanised sheets to reduced heat transfer.
The maximum temperature on the casing surface will not exceed 60°C.
Steam Drum and Fittings
The steam and water drums are fabricated using boiler steel plate of all welded construction.
The steam drum has a horizontal perforated baffle plate covering the entire water surface in order to prevent droplets of water rising to the upper part of the steam drum.
A steam separator is provided to completely remove the moisture.
The feedwater pipe enters the steam drum at the rear of the boiler and is attached to an internal perforated feed pipe which extends to the front of the steam drum.
This ensures that there is complete mixing of incoming feed with the existing boiler water and an equalising of temperatures.
The chemical feedwater treatment pipe attaches to the internal feedwater pipe and this also ensures that there is complete mixing of the chemicals before the water reaches the downcomers.
The open ended surface blow off internal pipe extends to the surface of the steam drum to ensure that only floating solids on the water
surface are discharged through this scum blowdown line.
The boiler blowdown connection is fitted to the lower part of the water drum.
Sootblower - Rotary Type
Operating Procedures
Procedure for Preparing the Boiler for Service
The following steps should be taken before attempting to flash up the boiler.
a)  All foreign materials must be removed from internal pressure parts.
b)  All gas side-heating surfaces must be clean and all refractory be in good condition.
c)  The furnace bottom and the burner wind box must been cleaned of oil and other debris.
d)  All personnel not involved must remain clear of the boiler.
e)  All manhole covers must be securely tightened.
f)   Inspect safety valves and ensure that gags have been removed and easing levers are in good condition.
g)  Open root valves for all instruments and controls connected to the boiler and check that they work as intended.
h) Open the vent valve of the steam drum.
i) Open all pressure gauge valves and check to ensure that all valves on the pressure gauge piping are open.
j) Check and close all blow-off valves and drain valves.
k) Fill the boiler until water level appears 25 to 50mm high in the gauge glasses.
Allow for swell in level after firing.
1) Check the operation of gauge glasses.
Remote reading instruments will not work correctly until the boiler is under pressure and so they must not be relied upon.
Raising Pressure With No Steam Available from the Other Boiler or Economiser
With the boiler water at the correct level and other checks made as above:
a) Set up the fuel system for diesel oil and circulate the fuel until all heavy fuel has been discharged from the fuel lines.
Ideally the fuel system should have been flushed through with diesel oil prior to the previous shutdown.
b)  Set the burner for air atomising, using an air pressure of 5 kg/cm2 and fuel pressure of 3 kg/cm2.
Purge the furnace with the forced draught fan for one minute with vanes fully open.
c)  Reduce the air pressure at the windbox to between 10 and 20mm WG and close recirculating valve.
d)  Light the burner using the pilot burner and adjust air and fuel pressure to ensure stabilised combustion by using the furnace
observation port and smoke indicator.
e)  When raising the pressure, keep the burner firing for 5 minutes and out of service for 15 minutes repeatedly at the lowest fuel oil
pressure (2.5kg/cm2) for one hour.
Again, repeatedly light and shut down the burner to raise pressure as recommended on the pressure raising curve supplied by the manufacturer. A guideline would be to aim for lkg/cm2 after 2 hours firing, 5kg/cm2 after 2.75 hours firing and 12 kg/cm2 after 3.25 hours firing.
f)   When the drum pressure has risen to about 2 kg/cm2, close the drum vent valve.
g)  Drain and warm through all steam supply lines to ancillary equipment before putting the boiler on load.
h) Supply steam to one of the HFO service tanks.
When the tank is of sufficient temperature to be pumped by the HFO pump, supply steam to the HFO heater and prepare to change over from DO to HFO firing.
The HFO must be thoroughly circulated through the system to ensure it is at the correct temperature for good combustion.
When firing on HFO, check the combustion and adjust the fuel and air as required, then continue pressure raising.
(Note ! Caution must be exercised when operating with diesel oil due to its lower flash point. Diesel oil must not be heated above 40°C and there is a greater risk of leakage compared with HFO.)
i) At working pressure, switch to automatic operation.

Raising Pressure with Steam Available from the Other Boiler or Economiser
a)  Start the forced draught fan, open the inlet vanes and purge the furnace.
b)  Ensure that the HFO system is correctly heated then start the HFO burning pump and circulate oil through the heater and burner
manifold, open the recirculating valve and discharge the cold HFO in the line.
(Note ! At normal sea going condition, the boiler fuel system should be continually circulating heated HFO.)
c)  Reduce the air pressure at the windbox to between 10 and 20mmWG.
d)  Close the recirculating valve.
e)  Light the burner and adjust the air and fuel pressure to ensure stabilised combustion, using the furnace observation port and
smoke indicator.
Boiler pressure must be raised gradually over a period of hours in accordance with the manufacturer's instructions.
The recommendations are the same as in item e) in the section; Raising Pressure With No Steam Available
f)   When the drum pressure has risen to about 2 kg/cm2, close the drum vent valve.
g)  Drain and warm through all steam supply lines to ancillary equipment before putting the boiler on load.
Shutting Down
a)  Operate sootblowers before shutting down the boiler whenever possible.
b)  Shut down the burner.
c)  Continue operation of the forced draught fan for a short while after shutting down, keeping an air pressure of 150mm WG at burner inlet and purge the furnace of combustible gases.
d)  Maintain the water level visible at about 50mm in the gauge glass and when the boiler is closed raise the water level 70mm to 120mm above the normal water level.
e)  Open the drum vent valve when the boiler pressure reaches about 2 kg/cm2.
f)   Change the fuel system to diesel oil and circulate back to the tank.
(Note ! If steam is to remain available from the other boiler or economiser, the boiler HFO system should remain in use and there is no need to change to diesel oil.)
g)  When fuel oil has been purged, shut down the fuel system.
After the boiler has been shut down for 4 hours the forced draught fan may be used to assist cooling down should immediate access be required. However, to avoid the risk of damage to refractory, allow the boiler to cool down under natural means if possible.
! CAUTION
Do not attempt to cool down the boiler by blowing down or by filling with cold water.

Know your ship. It's simple

Fouling and Fires in the Scavenge Air Spaces
The principle cause of fouling is blow-by of combustion products, unburnt fuel and cylinder lubricant between piston and cylinder into the scavenge air
spaces. The fouling will be greater if there is incomplete combustion of the fuel injected (exhaust smoke).
Causes of Poor Combustion:
The fuel injectors are not working correctly; incorrect fuel atomisation.
The fuel is at too low a temperature; resulting in high fuel viscosity and poor fuel atomisation.
Poorly adjusted injection pump timing; late injection results in after burning of fuel.
Operation with a temporary shortage of air during extreme variations in engine loading and with the charge air pressure dependent fuel limiter in the governor set too high.
Engine overloading; too much fuel for the available air.
Insufficient supply of air due to restricted engine room ventilation.
Fouling of the air intake filters and diffuser on the air side of the turbocharger.
Fouling of the air cooler, the air flaps in the charge air receiver and of the scavenge ports; these restrict air flow to the cylinders.
Fouling of the exhaust gas boiler; this increases the back pressure on the turbocharger turbines causing reduction in performance
and reduced air delivery.
Causes of Blow-by of Combustion Products:
Worn, sticking or broken piston rings.
Excessive liner wear or abnormal wear such as 'clover-leafing' which can also result in ring collapse and loss of piston ring to liner seal.
Individual cylinder lubricating quills are not working.


Damage to the running surface of the cylinder liners.
If one or more of these operating conditions prevails, residues, mainly consisting of incompletely burnt fuel and cylinder lubricating oil will
accumulate at the following points:
Between piston rings and piston ring grooves; this can result in the jamming of piston rings causing breakage or blow-past.
On the piston skirts. In the scavenge ports; this can affect the performance of the scavenging process resulting in incomplete
removal of combustion products from the cylinder and subsequent defective combustion.
On the bottom of the cylinder jacket (piston underside).
Causes of the Fires
The blow-by of hot combustion gases and sparks which have bypassed the piston rings between piston and cylinder liner running surface, enter the space
on the piston underside. Any residues present can ignite.
If there is after-burning of fuel in the cylinder due to late injection or poor fuel atomisation, the cylinder pressure, when the scavenge ports are uncovered, may be higher than the scavenge air pressure and hot combustion gases may enter the scavenge space.
A defective piston rod gland may allow oil from the crankcase to enter the scavenge space. The piston rod gland drains should be checked frequently for
signs of crankcase system oil as this indicates defective gland sealing rings.

Indications of a Fire
Sounding of the respective temperature alarms if the engine has the necessary monitoring instrumentation installed.
A considerable rise in the exhaust gas temperatures of the cylinder concerned and a general rise in charge air temperature.
The turbocharger may start surging.


Scavenge Space Fire Fighting Measures
The safety of shipboard personnel should be paramount whenever dealing with fires anywhere aboard ship.
Inform the bridge of the situation
Reduce engine power
Cut out the fuel injection pump of the cylinder concerned
Increase lubrication to the respective cylinder
(Note! If a serious fire occurs, shut down the engine after obtaining permission from the bridge and operate the fixed fire extinguishing system.)
A fire should have died down after 5 to 15 minutes. This can be verified by checking the exhaust gas temperatures and the temperatures of the doors to the piston bottoms.
Caution should be exercised whilst the fire is burning to ensure that it does not cause a fire in the engine room. Extreme care must be taken to ensure that
leakage of oil onto the hot scavenge space sides does not happen.
After it has been confirmed that the fire has been extinguished the engine must be stopped as soon as possible and the cause of the fire established. The
scavenge space must be allowed to cool completely before access doors are opened to allow inspection.
Checks should be made on the cylinder running surfaces, piston rings, fuel injectors, valve groups in the scavenge space, piston rod gland and liner seals.
Tie rod tension should be checked if the fire has been severe.
After a careful check, or if necessary repair, the engine can be put back on load with cut-in fuel injection pump and automatic cylinder lubrication.
Should a stoppage of the engine not be feasible and the fire has died down, the fuel injection pump can again be cut in, the load increased slowly and the
cylinder lubrication brought back again to the normal output. Avoid prolonged running with the considerably increased cylinder lubrication.
Preventive Measures
As can be seen from the causes, good engine maintenance goes a long way to safeguarding against fires in the scavenge air spaces. The following measures have a particularly favourable influence:
Use of correctly spraying fuel injectors and keeping the air and gas passages clean.
Optimum adjustment of the fuel cams and of the fuel injection pump timing.
When running continuously at reduced load, check the cylinder lubricating oil feed rate and readjust if necessary. Ensure that fuel atomisation and combustion is correct for the reduced load condition.
The permanent drain of residue from the piston underside must always be checked. To prevent accumulation of dirt, the drain cock on the collector main must be opened for a short time each day.
Prevention of Crankcase Explosions
The oil mist in the crankcase is inflammable over a very narrow range of mixture. Weaker or richer mixtures do not ignite. There must always be an
extraneous cause to set off ignition, such as hot engine components. Only under these circumstances and the presence of a critical mixture ratio of oil
mist and air can an explosion occur. A 'hot spot' is the common feature of all crankcase explosions and this can be due to metal-to-metal contact at a wiped bearing, rubbing guide, defective piston rod gland, damaged thrust, un-lubricated gear wheel, etc. or even due to a prolonged scavenge fire. The 'hot spot' provides the heat source to evaporate oil, which condenses to form mist-like droplets which will ignite readily, and ignite the mist. If the mist concentration in the crankcase reaches a critical level an explosion can occur.
Engines are equipped with an oil mist detector, which constantly monitors intensity of oil mist in the crankcase and triggers an alarm if the mist exceeds
the density limit.
Measures to be Taken When Oil Mist Has Occurred
a)  Do not stand near crankcase doors or relief valves or in corridors near doors to the engine room casing.
b)  Reduce speed to slowdown level immediately, if not already carried out automatically. Explain the situation and ask the bridge
for permission to stop.
c)  When the engine STOP order is received, stop the engine. Close the fuel oil supply. Maintain engine cooling and lubrication as the supply of lubricant will assist the cooling of the hot spot.
d)  Switch-off the auxiliary blowers.
e)  Open the skylight(s) and/or stores hatch.
f)   Leave the engine room as a fire can still occur even with the engine stopped because the mist will circulate in the crankcase and can come into contact with the hot spot.
g)  Lock the casing doors and keep away from them,


h) Prepare the fire-fighting equipment.
i) Do not open the crankcase until at least 20 minutes after stopping the engine. Ideally leave the engine for as long as possible before opening the crankcase doors as this will ensure that the hot spot has cooled below the ignition temperature and so any mist which persists will not ignite from this source. It is important that no naked lights exist in the vicinity of the crankcase when the doors are opened in order to prevent ignition of any residual mist from that source.
j) Stop the lubricating oil pump. Take off-open all the doors on one side of the crankcase. Cut off the starting air, and engage the turning gear.
Main Engine Graviner Oil Mist Detector

k) Locate the hot spot. Feel over, by hand, all the sliding surfaces (bearings, thrust bearing, piston rods, stuffing boxes, crossheads, lubricant supply toggle lever pipes, gears, vibration dampers, moment compensators, etc.)- Look for squeezed-out bearing metal and discolouration caused by heat (blistered paint, burnt oil, oxidised steel). Keep possible bearing metal found at the bottom of the oil tray for later analysing. Prevent further hot spots by
preferably making a permanent repair. Ensure that the respective sliding surfaces are in good condition. Take special care to check that the circulating oil supply is in order. The engine should not be restarted until the cause of the hot spot has been located and rectified.
1) Start the circulating oil pump and turn the engine by means of the turning gear. Check the oil flow from all bearings, spray pipes and spray nozzles in the crankcase, camshaft drive gear wheel case and thrust bearing. Check for possible leakages from pistons or piston rods.
m) Start the engine. After running for about 30 minutes stop and feel over surfaces for signs of abnormal temperature rise. Especially feel over the sliding surfaces which caused the overheating. There is a possibility that the oil mist is due to atomisation of the circulating oil, caused by a jet of air/gas, e.g. by combination of the following: Stuffing box leakages (not air tight). Blow-by through a cracked piston crown or piston rod (with direct connection to crankcase via the cooling oil outlet pipe). An oil mist could also develop as a result of heat from a scavenge fire being transmitted down the piston rod or via the stuffing box. Hot air jets or flames could also have passed through the stuffing box
into the crankcase.
WARNING
Special Engine Room Dangers
Keep clear of spaces below loaded cranes.
The opening of cocks may cause discharge of hot liquids or gases.
The dismantling of parts may cause the release of springs.
The removal of fuel valves or other valves in the cylinder cover may cause oil to run onto the piston crown. If the piston is hot an explosion may blow out the valve.
When testing fuel valves do not touch the spray holes as the jets may pierce the skin.
Beware of high-pressure oil leaks when using hydraulic equipment, wear protective clothing.
Arrange indicator cocks with pressure relief holes directed away from personnel, wear goggles when using indicator equipment.
Do not weld in the engine room if the crankcase is opened before fully cooled.
Turning gear must be engaged before working on or inside the engine as the wake from other ships in port or waves at sea may cause the propeller to turn. Also, isolate the starting air supply.
Use warning notices at the turning gear starter and other control stations to warn personnel that people are working on the engine.
Use gloves when removing O-rings and other rubber/plastic based sealing materials, which have been subjected to abnormally high
working temperatures as they may have a caustic effect.
Do not allow oil patches to remain on floors as personnel can easily slip resulting in injury.
Oil spills, and particularly oily rags, anywhere present a fire hazard.
Do not remove fire extinguishers from designated positions and ensure that any fire extinguishers which have been used are replenished immediately.
Only use lifting equipment which has current certification.

Main Engine Manoeuvring Control

Courtesy By NORCONTROL Automation AS



Engine Telegraph System (ETS)
Manufacturer: NORCONTROL Automation AS
Model: AutoChief - 4


Description
The ETS performs two basic functions, these are:
1. To allow an operator to initiate engine change commands from the
designated control location directly to the engine via the remote
control system. These changes can also be communicated, via the
ETS pushbuttons and telegraph handle, to an operator who will
implement these commands in the control room or the engine
room.

International Maritime Solid Bulk Cargoes Code (IMSBC Code)


The International Maritime Solid Bulk Cargoes Code (IMSBC Code) has now replaced the Code of Safe Practice for Solid Bulk Cargoes (BC Code) w.e.f 01st January 2011, which was first adopted as a recommendatory code in 1965 and has been updated at regular intervals since then.
The aim of the mandatory IMSBC Code is to facilitate the safe stowage and shipment of solid bulk cargoes by providing information on the dangers associated with the shipment of certain types of cargo and instructions on the appropriate procedures to be adopted.

Wednesday, November 23, 2011

Adopting a convention, Entry into force, Accession, Amendment, Enforcement, Tacit acceptance procedure

​Introduction
The industrial revolution of the eighteenth and nineteenth centuries and the upsurge in international commerce which followed resulted in the adoption of a number of international treaties related to shipping, including safety.  The subjects covered included tonnage measurement, the prevention of collisions, signalling and others.
By the end of the nineteenth century suggestions had even been made for the creation of a permanent international maritime body to deal with these and future measures.  The plan was not put into effect, but international co-operation continued in the twentieth century, with the adoption of still more internationally-developed treaties.
Adopting a convention
This is the part of the process with which IMO as an Organization is most closely involved.  IMO has six main bodies concerned with the adoption or implementation of conventions.  The Assembly and Council are the main organs, and the committees involved are the Maritime Safety Committee, Marine Environment Protection Committee, Legal Committee and the Facilitation Committee.  Developments in shipping and other related industries are discussed by Member States in these bodies, and the need for a new convention or amendments to existing conventions can be raised in any of them.

Entry into force
The adoption of a convention marks the conclusion of only the first stage of a long process.  Before the convention comes into force - that is, before it becomes binding upon Governments which have ratified it - it has to be accepted formally by individual Governments.

Signature, ratification, acceptance, approval and accession
The terms signature, ratification, acceptance, approval and accession refer to some of the methods by which a State can express its consent to be bound by a treaty.
Signature
Consent may be expressed by signature where:
  • the treaty provides that signature shall have that effect;
  • it is otherwise established that the negotiating States were agreed that signature should have that effect;
  • the intention of the State to give that effect to signature appears from the full powers of its representatives or was expressed during the negotiations (Vienna Convention on the Law of Treaties, 1969, Article 12.1).
A State may also sign a treaty "subject to ratification, acceptance or approval".  In such a situation, signature does not signify the consent of a State to be bound by the treaty, although it does oblige the State to refrain from acts which would defeat the object and purpose of the treaty until such time as it has made its intention clear not to become a party to the treaty (Vienna Convention on the Law of Treaties, Article 18(a)).
Signature subject to ratification, acceptance or approval
Most multilateral treaties contain a clause providing that a State may express its consent to be bound by the instrument by signature subject to ratification.
In such a situation, signature alone will not suffice to bind the State, but must be followed up by the deposit of an instrument of ratification with the depositary of the treaty.
This option of expressing consent to be bound by signature subject to ratification, acceptance or approval originated in an era when international communications were not instantaneous, as they are today.
It was a means of ensuring that a State representative did not exceed their powers or instructions with regard to the making of a particular treaty. The words "acceptance" and "approval" basically mean the same as ratification, but they are less formal and non-technical and might be preferred by some States which might have constitutional difficulties with the term ratification.
Many States nowadays choose this option, especially in relation to multinational treaties, as it provides them with an opportunity to ensure that any necessary legislation is enacted and other constitutional requirements fulfilled before entering into treaty commitments.
The terms for consent to be expressed by signature subject to acceptance or approval are very similar to ratification in their effect.  This is borne out by Article 14.2 of the Vienna Convention on the Law of Treaties which provides that "the consent of a State to be bound by a treaty is expressed by acceptance or approval under conditions similar to those which apply to ratification."

Accession
Most multinational treaties are open for signature for a specified period of time. Accession is the method used by a State to become a party to a treaty which it did not sign whilst the treaty was open for signature.
Technically, accession requires the State in question to deposit an instrument of accession with the depositary. Article 15 of the Vienna Convention on the Law of Treaties provides that consent by accession is possible where the treaty so provides, or where it is otherwise established that the negotiating States were agreed or subsequently agreed that consent by accession could occur.

Amendment
Technology and techniques in the shipping industry change very rapidly these days. As a result, not only are new conventions required but existing ones need to be kept up to date. For example, the International Convention for the Safety of Life at Sea (SOLAS), 1960 was amended six times after it entered into force in 1965 - in 1966, 1967, 1968, 1969, 1971 and 1973. In 1974 a completely new convention was adopted incorporating all these amendments (and other minor changes) and has itself been modified on numerous occasions.
In early conventions, amendments came into force only after a percentage of Contracting States, usually two thirds, had accepted them. This normally meant that more acceptances were required to amend a convention than were originally required to bring it into force in the first place, especially where the number of States which are Parties to a convention is very large.
This percentage requirement in practice led to long delays in bringing amendments into force. To remedy the situation a new amendment procedure was devised in IMO. This procedure has been used in the case of conventions such as the Convention on the International Regulations for Preventing Collisions at Sea, 1972, the International Convention for the Prevention of Pollution from Ships, 1973 and SOLAS 1974, all of which incorporate a procedure involving the "tacit acceptance" of amendments by States.
Instead of requiring that an amendment shall enter into force after being accepted by, for example, two thirds of the Parties, the “tacit acceptance” procedure provides that an amendment shall enter into force at a particular time unless before that date, objections to the amendment are received from a specified number of Parties.
In the case of the 1974 SOLAS Convention, an amendment to most of the Annexes (which constitute the technical parts of the Convention) is `deemed to have been accepted at the end of two years from the date on which it is communicated to Contracting Governments...' unless the amendment is objected to by more than one third of Contracting Governments, or Contracting Governments owning not less than 50 per cent of the world's gross merchant tonnage. This period may be varied by the Maritime Safety Committee with a minimum limit of one year.
As was expected the "tacit acceptance" procedure has greatly speeded up the amendment process.  Amendments enter into force within 18 to 24 months, generally  Compared to this, none of the amendments adopted to the 1960 SOLAS Convention between 1966 and 1973 received sufficient acceptances to satisfy the requirements for entry into force.

Enforcement
The enforcement of IMO conventions depends upon the Governments of Member Parties.
Contracting Governments enforce the provisions of IMO conventions as far as their own ships are concerned and also set the penalties for infringements, where these are applicable.
They may also have certain limited powers in respect of the ships of other Governments.
In some conventions, certificates are required to be carried on board ship to show that they have been inspected and have met the required standards.  These certificates are normally accepted as proof by authorities from other States that the vessel concerned has reached the required standard, but in some cases further action can be taken.
The 1974 SOLAS Convention, for example, states that "the officer carrying out the control shall take such steps as will ensure that the ship shall not sail until it can proceed to sea without danger to the passengers or the crew".
This can be done if "there are clear grounds for believing that the condition of the ship and its equipment does not correspond substantially with the particulars of that certificate".
An inspection of this nature would, of course, take place within the jurisdiction of the port State.  But when an offence occurs in international waters the responsibility for imposing a penalty rests with the flag State.
Should an offence occur within the jurisdiction of another State, however, that State can either cause proceedings to be taken in accordance with its own law or give details of the offence to the flag State so that the latter can take appropriate action.
Under the terms of the 1969 Convention Relating to Intervention on the High Seas, Contracting States are empowered to act against ships of other countries which have been involved in an accident or have been damaged on the high seas if there is a grave risk of oil pollution occurring as a result.
The way in which these powers may be used are very carefully defined, and in most conventions the flag State is primarily responsible for enforcing conventions as far as its own ships and their personnel are concerned.
The Organization itself has no powers to enforce conventions.
However, IMO has been given the authority to vet the training, examination and certification procedures of Contracting Parties to the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW), 1978. This was one of the most important changes made in the 1995 amendments to the Convention which entered into force on 1 February 1997. Governments have to provide relevant information to IMO's Maritime Safety Committee which will judge whether or not the country concerned meets the requirements of the Convention.

Relationship between Conventions and interpretation
Some subjects are covered by more than one Treaty. The question then arises which one prevails. The Vienna Convention on the Law of Treaties provides in Article 30 for rules regarding the relationship between successive treaties relating to the same subject-matter. Answers to questions regarding the interpretation of Treaties can be found in Articles 31, 32 and 33 of the Vienna Convention on the Law of Treaties. A Treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose. When a Treaty has been authenticated in two or more languages, the text is equally authoritative in each language, unless the treaty provides or the parties agree that, in case of divergence, a particular text shall prevail.
Uniform law and conflict of law rules
A substantive part of maritime law has been made uniform in international Treaties. However, not every State is Party to all Conventions and the existing Conventions do not always cover all questions regarding a specific subject. In those cases conflict of law rules are necessary to decide which national law applies. These conflict of law rules can either be found in a Treaty or, in most cases, in national law.

IMO conventions
The majority of conventions adopted under the auspices of IMO or for which the Organization is otherwise responsible, fall into three main categories.
The first group is concerned with maritime safety; the second with the prevention of marine pollution; and the third with liability and compensation, especially in relation to damage caused by pollution.  Outside these major groupings are a number of other conventions dealing with facilitation, tonnage measurement, unlawful acts against shipping and salvage, etc.

Tacit acceptance procedure
The amendment procedures contained in the first Conventions to be developed under the auspices of IMO were so slow that some amendments adopted have never entered into force. This changed with the introduction of the "tacit acceptance" procedure.
Tacit acceptance is now incorporated into most of IMO's technical Conventions. It facilitates the quick and simple modification of Conventions to keep pace with the rapidly-evolving technology in the shipping world. Without tacit acceptance, it would have proved impossible to keep Conventions up to date and IMO's role as the international forum for technical issues involving shipping would have been placed in jeopardy.
In the spring of 1968, IMO - then still called IMCO, the Inter-Governmental Consultative Organization - celebrated the 20th anniversary of the adoption of the IMO Convention. It should have been an occasion for some congratulations. But all was not well. Many of the Organization's Member States were not happy with the progress that had been made so far.
Many were concerned about the Organization's structure and its ability to respond to the changes taking place in shipping. In March, 1967, the oil tanker Torrey Canyon had gone aground off the coast of England, resulting in what was then the world's biggest oil spill. IMO was called upon to take action to combat oil pollution and to deal with the legal issues that arose. But would it be able to do so?
The general disquiet was summed up by Canada in a paper submitted to the 20th session of the IMO Council in May 1968. It stated that "the anticipations of twenty years ago have not been fulfilled" and went on to complain of the effort required by Member States in attending meetings and dealing with the technical problems raised by IMO. The paper was discussed by the Council which agreed to establish a working group to prepare a draft statement of the objectives of IMO and an inventory of further objectives which the Organization could usefully fulfil in the field of international maritime transport.
In November 1968 the working group reported back to the Council. It outlined a list of activities, far broader than the programmes undertaken by IMO so far. This was approved by the Council, which also agreed that IMO needed to improve its working methods.
The working group was asked to report to the Council again at its 22nd session in May 1969.This time it put forward a number of proposals for improving IMO's working methods, the most important of which concerned the procedures for amending the various Conventions that had been adopted under IMO's auspices.
The problem facing IMO was that most of its Conventions could only be updated by means of the "classical" amendment procedure. Amendments to the 1960 SOLAS Convention, for example, would enter into force "twelve months after the date on which the amendment is accepted by two-thirds of the Contracting Governments including two-thirds of the Governments represented on the Maritime Safety Committee. This did not seem to be a difficult target when the Convention was adopted, because to enter into force the Convention had to be accepted by only 15 countries, seven of which had fleets consisting of at least 1 million gross tons of merchant shipping.
But by the late 1960s the number of Parties to SOLAS had reached 80 and the total was rising all the time as new countries emerged and began to develop their shipping activities. As the number of Parties rose, so did the total required to amend the Convention. It was like trying to climb a mountain that was always growing higher and the problem was made worse by the fact that Governments took far longer to accept amendments than they did to ratify the parent Convention.
The Council approved the working group's proposal that "it would be a useful first step to undertake a comparative study of the conventions for which IMO is depositary and similar instruments for which other Members of the United Nations family are responsible." This proposal was endorsed by the 6th regular session of the IMO Assembly in October 1969 and the study itself was completed in time to be considered by the Assembly at its 7th session in 1971.
It examined the procedures of four other UN agencies: the International Civil Aviation Organization (ICAO), the International Telecommunications Union (ITU), the World Meteorological Organization (WMO) and the World Health Organization (WHO).
It showed that all of these organizations were able to amend technical and other regulations. These amendments became binding on Member States without a further act of ratification or acceptance being required.
On the other hand, IMO had no authority to adopt, let alone amend conventions. Its mandate allowed it only to "provide for the drafting of conventions, agreements or other instruments and to recommend these to Governments and to intergovernmental organizations and to convene such conferences as may be necessary." Article 2 of the IMO Convention specifically stated that IMO's functions were to be "consultative and advisory".
The Organization could arrange a conference - but it was up to the conference to decide whether the Convention under discussion should or should not be adopted and to decide how it should be amended. The study concluded that "any attempt to bring IMO procedure and practice into line with the other organizations would, therefore, entail a change either in the constitutional and institutional structure of the Organization itself or in the procedure and practice of the diplomatic conferences which adopt the conventions of IMO.
The first might involve an amendment to the IMO Convention itself. The second might require that diplomatic conferences convened by IMO should grant greater power to the organs of IMO in regard to the review and revision of the instruments.
The study was discussed at length by the Assembly. Canada pointed out that the amendments adopted to the 1960 SOLAS Convention in 1966, 1967, 1968 and 1969 had failed to enter into force and this "sufficed to show that IMO would henceforth have to tackle serious institutional problems." A note submitted to the conference by Canada stated that "unless the international maritime community is sufficiently responsive to these changed circumstances, States will once again revert to the practice of unilaterally deciding what standards to apply to their own shipping and to foreign flag shipping visiting their ports."
The result was the adoption of resolution A.249(VII) which referred to the need for an amendment procedure "which is more in keeping with the development of technological advances and social needs and which will expedite the adoption of amendments." It called for the Legal Committee and Maritime Safety Committee to prepare draft proposals for consideration by the 8th Assembly.
A growing urgency was added by the fact that IMO was preparing a number of new conventions for adoption during the next few years. Conferences to consider a new Convention on the International Regulations for Preventing Collisions at Sea and an International Convention for Safe Containers were both scheduled for 1972, a major Convention dealing with the Prevention of Marine Pollution from Ships for 1973 and a conference to revise SOLAS was scheduled for 1976. All of these treaties required a new, easier amendment procedure than the traditional method.
The MSC discussed the amendment question at its 25th session in March 1972. A working group was formed to discuss the matter in detail and concluded that at current rates of acceptance the requisite "two-thirds" target needed to amend SOLAS 1960 "will not be achieved...for many years, possibly never." Moreover, any future amendments would almost certainly suffer the same fate. This would include any amendments intended to improve the amendment procedure itself.
The working group reported: "It follows that the only realistic way of bringing an improved amending procedure into effect within a reasonable period of time is to incorporate it into new or revised technical conventions.
A few weeks later, the Legal Committee held its 12th session. Among the documents prepared for the meeting was a report on discussions that had taken place at the MSC and a detailed paper prepared by the Secretariat. The paper analysed the entry into force and amendment processes of various IMO Conventions and referred to two possible methods that had been considered by the Assembly, for speeding up the amendment procedure. Alternative I was to revise each Convention so that greater authority for adopting amendments might be delegated to the appropriate IMO organs. Alternative II was to amend the IMO Convention itself and give IMO the power to amend Conventions.
The study then considered Alternative I in greater detail. The main reason why amendments took so long to enter into force was the time taken to gain acceptance by two-thirds of Contracting Governments. One way of reducing this period would be by "specifying a date ...of entry into force after adoption by the Assembly, unless that date of amendment is explicitly rejected by a certain number or percentage of Contracting Governments." The paper said that this procedure "has the advantage that all Contracting Governments would be able to advance the preparatory work for implementing the amended regulations and the industry would be in a position to plan accordingly."
The Committee established a working group to consider the subject and prepared a preliminary study based on its report, which again referred to the disadvantages of the classical amendment system. The study continued: "The remedy for this, which has proved to be workable in practice, in relation to a number of conventions, is what is known as the 'tacit' or 'passive' acceptance procedure. This means that the body which adopts the amendment at the same time fixes a time period within which contracting parties will have the opportunity to notify either their acceptance or their rejection of the amendment, or to remain silent on the subject. In case of silence, the amendment is considered to have been accepted by the party...".
The tacit acceptance idea immediately proved popular. The Council, at its meeting in May, decided that the next meeting of the Legal Committee should consist of technical as well as legal experts so that priority could be given to the amendment issue. The Committee was asked to give particular attention to tacit acceptance.
The idea was given non-governmental support by the International Chamber of Shipping, which had consultative status with IMO and submitted a paper stating that the lack of an effective amendment procedure created uncertainties and was detrimental to effective planning by the industry. The classical procedure had also encouraged some governments to introduce unilateral legislation that, however well intentioned, was "seriously disruptive to international shipping services." The paper said that if other Governments did the same " the disruption to international shipping and the world trade which it serves would become increasingly severe. Such unilateral action strikes at the purpose of IMO."
By the time the Legal Committee met for its 14th session in September 1972, there was general agreement that tacit acceptance offered the best way forward. Other ideas, such as amending the IMO Convention itself, had too many disadvantages and would take too long to introduce. There was some concern about what would happen if a large number of countries did reject an amendment and the Committee members agreed that tacit acceptance should apply only to the technical content of Conventions, which was often contained in annexes. The non-technical articles should continue to be subject to the classical (or "positive") acceptance procedure.
The Committee also generally agreed that alternative procedures for amending the technical provisions should be retained but it did not reach consensus on another issue: should amendments be prepared and adopted by an appropriate IMO body, such as the Maritime Safety Committee - or by Contracting Parties to the Convention concerned? This was an important point at the time, since many Contracting Parties to IMO Conventions were not yet Members of IMO itself and might object to treaties they had ratified being amended without them even being consulted.
This issue was still unsettled when the Conference on Revision of the International Regulations for Preventing Collisions at Sea opened in October 1972. The purpose of the conference was to update the Collision Regulations and to separate them from the SOLAS Convention (the existing regulations were annexed to SOLAS 1960).
The amendment procedure is contained in Article VI. Amendments to the Collision Regulations adopted by the MSC (by a two-thirds majority) have to be communicated to Contracting Parties and IMO Member States at least six months before being considered by the Assembly. If adopted by the Assembly (again by a two-thirds majority), the amendments enter into force on a date determined by the Assembly unless more than one third of Contracting Parties notify IMO of their objection. On entry into force, any amendment shall "for all Contracting Parties which have not objected to the amendment, replace and supersede any previous provision to which the amendment refers."
Less than two months later, on 2 December 1972 a conference held in Geneva adopted the International Convention for Safe Containers, Article X of which contains procedures for amending any part or parts of the Convention. The procedure is the traditional "positive" acceptance system, under which amendments enter into force twelve months after being adopted by two-thirds of Contracting Parties. However, Article XI contains a special procedure for amending the technical annexes which also incorporates tacit acceptance. The procedure is slightly different from that used in the Collision Regulations, one difference being that the amendments can be adopted by the MSC "to which all Contracting Parties shall have been invited to participate and vote." This answered the question of how to take into account the interests of Parties to Conventions that were not Member States of IMO.
The next Convention to be considered was the International Convention for the Prevention of Pollution from Ships (MARPOL), which was successfully adopted in May 1973. It, too, incorporated tacit acceptance procedures for amending the technical annexes. In the meantime, IMO was preparing for a new SOLAS convention. This was considered necessary because none of the amendments adopted to the 1960 version had entered into force and did not appear likely to do so in the near future. The 1966 Load Lines Convention also contained a classical amendment procedure and the intention was to combine the two instruments in a new Convention, which was scheduled to be considered in 1976.
The MSC discussed this proposal at its 26th session in October-November, but it was clear that this would be a daunting and time-consuming task. The combined instrument might be a good idea for the future - but the real priority was to get the amendments to SOLAS 1960 into force as quickly as possible and to make sure that future amendments would not be delayed. A working group was set up to consider the various alternatives, but opinion began to move in favour of a proposal by the United Kingdom that IMO should concentrate on an interim Convention designed to bring into force the amendments adopted since 1960. The new Convention, it was suggested, would consist of the 1960 text with the addition of a tacit acceptance amendment procedure and the addition of amendments that had already been adopted.
Another advantage, the United Kingdom pointed out, was that the conference called to adopt the revised Convention "might be held considerably earlier than 1976 since comparatively little preparation would be needed." The subject was discussed again at the MSC's 27th session in the spring of 1973 and, although some delegations wanted a more comprehensive revision, others felt that the workload would be so great that the conference would be seriously delayed. By a vote of 12 in favour and four abstentions, the Committee decided to call a conference with limited scope, as proposed by the United Kingdom.
On 21 October, 1974, the International Conference on Safety of Life at Sea opened in London and on 1 November a new SOLAS Convention was adopted, which incorporated the tacit acceptance procedure.
The tacit acceptance amendment procedure has now been incorporated into the majority of IMO's technical Conventions and has been extended to some other instruments as well. Its effectiveness can be seen most clearly in the case of SOLAS 1974, which has been amended on many occasions since then. In the process, the Convention's technical content has been almost completely re-written.

http://www.imo.org

Wednesday, October 12, 2011

General Engineering Questions

General
Q.Starting from a cold ship, the emergency generator is running flash the ship up to full away
Q.Describe the location of General alarm push buttons in the engineroom
Q. Talk through an engineroom walkround on your last vessel


Steering gear
Q. Describe the emergency steering procedure on you last vessel
Q. Describe the steering gear fitted to your last vessel - for electro hydraulic plant he may be interested in the power supply
Q. What is special about the overload protection for the steering gear motors

Short Circuit protection and were appropriate-single phase protection is fitted. In addition instead of overcurrent protection an Overload alarm is fitted set to operate at not less than twive normal running current.
Q. Describe the steering gear tests before leaving port
Q. Describe the workings of the steering gear hunting gear- including protection for heavy sea effects on the rudder.
Q describe the daily checks you make on the steering gear
Q Describe the effects of air in the steering gear ( if you have hydraulic telemotors system - the effects of air in this)


Bilge systems
Q. Describe the restrictions for pumping bilge water with respect to you last vessel (be aware of latest M-Notices)
Q. What checks are made on the operation of the Bilge separator
Q. Describe the procedure for pumping bilges
Q. What alarms and shutdowns are fitted
Q what special provision is made for evacuating the bilges i.e emergency suctions/pumps including cargo areas.
Q. Give likely causes to poor pumping performance of the bilge system


Fuel system
Q. Sketch and describe the fuel system on your last vessel
Q. What safety devices, alarms and shut downs are fitted
Q. What problems would be cause by over/under heating of the fuel ( Heavy or marine fuel oil only)
Q. Describe the procedure for changing over form Heavy to Diesel and vice versa - Be very, very careful here as it is not as easy as what it sounds !!
Q. Describe the effects of water contamination, what are the likely sources, how would you rectify the problem
Q. What protection is there against fuel leakage
Q. Describe the procedure for transfer/ loading of bunkers


Cooling water
Q. Sketch and describe the system fitted to your last vessel
Q. What safety devices, alarms and shut downs are fitted
Q. Describe the cooling water treatment, testing , expected results, effects of under/over treatment
Q. What temperature regulation was fitted on the fresh water system, what are the effects of under/over cooling on the plant


Power generation
Q. Describe the power generation plant fitted to your last vessel
Q. Describe the method of running up the prime mover ( steam and/or motor)- you may be asked about the protection devices fitted as well as any routing testing done and daily checks
Q. Describe the method of synchronising a generator on to a live board
Q. What are the effects of putting a generator on to a live board, what is the protection against this.
Q. Describe the protection devices fitted on the main bus bars and distribution circuits
Q. what provision is there for electrical supply following failure of the main generation plant
Q. Where are the location of emergency 24v lighting.


Fixed fire fighting and protection
Q. What daily checks are carried out on the fire and smoke detection equipment - this is not as easy as it appears.
Q. Describe the location of fire and smoke detection heads
Q. Describe the different types of smoke and fire detection equipment fitted to your last vessel
Q. What is the procedure following the activation of a smoke /fire detector -- or general alarm
Q. Describe the workings of certain types of detector- you would be very unlucky to get this one
Q Describe the various fire protection systems fitted to your last vessel
Q. Describe the procedure before release of the bulk Fire fighting system into the machinery space
Q. What type of portable extinguisher would be used on ---- fire ( fill in the blank)
Q. describe the testing, refilling procedure for various portable fire fighting devices
Q. Describe the testing procedure of the bulk fixed fire fighting installation
Q. Describe the dangers of having combination Bilge/ Ballast/ Fire fighting pumps
Q. Describe the testing and requirements of the emergency fire fighting system on your last vessel


Boilers
Q. Describe the safety devices fitted to a boiler
Q. describe your routine checks
q. describe the blowdown procedure for a gauge glass- very common question
Q. Describe the procedure for flashing the boiler
Q. Describe the effects of insufficient/ too much air supply
Q. Describe the Requirements for testing of boiler/ feed water.
Q. Describe the procedure for testing of boiler/Feed water- give expected results
q. what are the effects of over/under chemical dosing
Q. What are the safety precautions when dealing with boiler chemicals
Q. Describe the procedure for testing boiler safety valves
Q. Describe the Boiler mountings fitted on you last vessel
Q. What are the dangers of lighting a boiler without proper purging
Q. Describe a furnace inspection carried out on your last vessel
Q. Describe the procedure for blowing soot. How often carried out
Q. What are the effects of insufficient soot blow
Q. describe your action when dealing with an uptake ( economiser fire)
Q. Describe your actions when dealing with a windbox fire
Q. Describes your action in the event of insufficient feed water generation capacity. - really a class two question but he may require you to demonstrate a knowledge of water consumption with the plant.


Main engine-Steam Turbine
Q. Describe the safety devices fitted
Q. describe the routine checks carried out
Q. Describe the procedure for preparing and shutting down the engine prior to and after sailing
Q. Explain the need for warming through
Q. describe the need for turning the engine when on stand-by
Q. Describe the effects of insufficient/too much gland steams supply
Q. Describe the effects of loss of condenser vacuum
Q. Describe the effects of salt water leakage into the condenser
Q. Describe the effects of operating the vessel with a partially shut throttling valve - ALmost certainly class two only
Q. Explain the reasons for and effects of boiler carryover
Q. Describe the consequences of operating the plant with too high/ Low superheat temperature
Q. describe the need for boiler steam superheating


Main engine-Diesel
( some of these may be asked in regard to diesel generators fitted to vessels you have sailed on.
Q. Describe the safety devices fitted
Q. describe the routine checks carried out
Q. Explain the need for pre-heating by heating the jacket water
Q. Describe the procedure for preparing and shutting down the engine prior to and after sailing
Q. describe the need for turning the engine when preparing the engine
Q. Describe a crankcase/Scavenge inspection
Q. Describe the effects of under/over cylinder lubrication- slow speed
Q. describe your action when dealing when dealing with a scavenge fire
Q. describe your action when dealing with an uptake ( economiser) fire


FILTRATION, POLLUTION, SEWAGE
01. (i) Sketch a self-cleaning filter as commonly incorporated in main lubricating oil systems, labeling the principal components and showing the direction of oil flow. ( 4 marks)
(ii) Explain how the filter functions ( 4 marks)
(iii) Suggest why the quality of filtration is directly related to oil flow rate. ( 1 mark)
(iv) State why heavy 'build up' of residue in the filter should be avoided for reasons other that restriction of oil flow. . ( 1 mark)
2. (i) Suggest with reasons whether static filters should be cleaned : ( 7 marks)
At regular intervals of time,
Or after a prescribed number of operational hours,
Or when filter condition warrants it.
(ii) State with reasons how static filtration can be improved n practice. (3 marks)

3. Give reasons why each of following conditions can result in oil being discharged with the water from a static oily water separator :
(i) High oil density, (3 marks)
(ii) Low mixture temperatures, ( 3 marks)
(iii) High pumping rate, (2 marks)
(iv) Oil/water interface below test cocks ( 2 marks)

4. (i) Draw a line diagram of a zero discharge (self contained) sewage system, labelling the principal items and showing the direction of flow in all lines. (4 marks)
Describe how the effluent is :
(ii) Collected and stored, (3 marks)
(iii) Treated for discharge ashore or destruction aboard (3 marks)

5. Give reasons why each of the following conditions in oily water separators can result in oil carry over with the water :
(i) High throughput of mixture (2 marks)
(ii) Low temperature of mixture, ( 2 marks)
(iii) Considerable oil content in mixture, (2 marks)
(iv) High density of oil. ( 2 marks)
(v) Outline the value of test cocks. ( 2 marks)

6. Give reasons why each of the following conditions in centrifuges can result in oil carry-over with the water :
(i) High throughput of mixture, (2 marks)
(ii) Low temperature of mixture, ( 2 marks)
(iii) Considerable sediment suspension in mixture, ( 2 marks)
(iv) Considerable oil content in mixture, (2 marks)
(v) Bowl speed below designed speed. ( 2 marks)

7. (i) Sketch the bowl of an automatic self cleaning centrifuge, labelling the principal components and showing the direction of flow of all fluids. (4 marks)
(ii) State with reasons what protection is provided against malfunction. ( 3 marks)
(iii) State why air filters are fitted to air compressors and diesel engines. (3 marks)
(iv) State why oil filters are normally fitted between fuel and lubricating oil tanks and their respective pumps. ( 3 marks)
8. Explain how the following conditions contribute to the satisfactory performance of oil centrifuges :
(i) Negligible clutch slip in bowl dirve, ( 2 marks)
(ii) Reasonable internal cleanliness of bowl, ( 2 marks)
(iii) Low rate of feed of contaminated oil, ( 2 marks)
(iv) Contaminated oil preheated prior to centrifuging, ( 2 marks)
(v) Contaminated oil allowed to stand for an appreciable time in settling tank prior to centrifuging. ( 2 marks)

9. Explain how the following conditions contribute to the satisfactory performance of oil centrifuges :
(i) Negligible clutch slip in bowl drive, ( 2 marks)
(ii) Reasonable internal cleanliness of bowl, ( 2 marks)
(iii) Low rate of feed of contaminated oil, ( 2 marks)
(iv) Contaminated oil preheated prior to centrifuging( 2 marks),
(v) Contaminated oil allowed to stand for an appreciable time in settling tank prior to centrifuging. ( 2 marks)

10. With reference to oil centrifuges state why :
(i) They are used for oil contaminated by water, but are not used for water contaminated by oil. (3 marks)
(ii) They do not render static filters redundant, ( 3 marks)
(iii) Severe bowl vibration may occur in service, ( 2 marks)
(iv) Bowl may spin at a reduced speed. ( 2 marks)

11 Sketch a static oily water separator intended to handle large quantities of heavily contaminated water, labelling the principal components, showing the internal arrangement of subdivision, baffles and fittings, and indicating the direction of fluid flow in all parts. (4 marks)
Describe how it operates. (4 marks)

12 Give two reasons why oil might be carried over with the water. (2 marks)
Draw a line diagram of a zero discharge sewage system in which the water is recirculated and the solids processed for disposal, labelling the principal components and showing the direction of flow in all lines. (4 marks)
Describe how the system operates. (4 marks)

13 Give reasons why this system might be considered superior to that in which the sterile water is discharged overboard at sea. (2 marks)
Sketch a 'self cleaning' filter as commonly incorporated in main lubrication systems, showing in detail the filter pack. (3 marks)
Describe how foreign matter in the oil is captured. ( 2 marks)
Identify with reasons that part of th filter mechanism which basically determines the maximum size of the suspended solids arrested. ( 2 marks)
Define the indications that such a filter requires cleaning. ( 1 mark)
Give two reasons why heavily foulded filters require immediate attention. ( 2 marks)

14 Give reasons why each of the following conditions can result in oil being carried over with the water discharge from lubricating oil centrifuges :
(i) high throughput of mixture ( 3 marks)
(ii) abnormally high temperature of mixture (3 marks)
(iii) appreciable accumulation of solids in bowl (4 marks)

15. (i) Give reasons why magnetic filters normally complement static filters in main lubricating oil systems where bearing surfaces are of non- ferrous nature.
(ii) Identify the source and nature of deposits found in such filters.
(iii) Explain how the quantity and quality of the collected deposits give a good indication of conditions prevailing in the main machinery. ( 3 marks)
(iv) State why centrifuges do not render magnetic filters redundant. ( 1 mark)

16 With reference to oil centrifuges :
(i) Differentiate between the roles of purifiers and classifiers, ( 3 marks)
(ii) Explain how fluids of differing characteristics and degrees of contamination can be handled individually by one machine. ( 4 marks)
(iii) Give reasons why settling tanks do not make the use of centrifuges redundant. (3 marks)

17. (i) Give reasons why magnetic filters normally complement static filters in main lubricating oil systems where bearing surfaces are of a non-ferrous nature. ( 3 marks)
(ii) Identify the source and nature of deposits found in such filters. ( 3 marks)
(iii) Explain how the quantity and quality of the collected deposits give a good indication of conditions prevailing in the main machinery. (3 marks)
(iv) State why centrifuges do not render magnetic filters redundant. ( 1 mark)

18. With reference to static oily water separators :
(i) Explain how efficiency is related to mass flow rate, ( 2 marks)
(ii) Define the contribution of coagulators to efficiency, ( 2 marks)
(iii) Explain how internal baffles and subdivisional screens affect separation, ( 2 marks)
(iv) Define the value of air release values, ( 2 marks)
(v) Give reasons why rotary positive displacement pumps are preferable for supply duties rather than centrifugal pumps. ( 2 marks)

19. (i) Draw a line diagram of a sewage system in which the holding tank is small when compared to the amount of sewage ( 4 marks)
(ii) Describe how the system operates ( 4 marks)
(iii) State why the holding tank is small compared to other systems ( 2 marks)

20. (a) Draw a line diagram of a biological sewage system in which only sterile water is discharged overboard at sea, labelling the principle items and showing the direction of flow in all lines. ( 4 marks)
(b) Describe briefly how it operates. ( 4 marks)
(c) Define its principal disadvantages. ( 2 marks)

21. (a) Draw a line diagram of a biological sewage system in which only sterile water is discharged overboard at sea, labelling the principle items and showing th direction of flow in all lines. ( 4 marks)
(b) Explain how it operates. ( 3 marks)
(c) State three advantages it has over other sewage systems ( 3 marks)

22. Give reasons why each of the following conditions can result in oil being discharged with the water from a static oily water separator :
(a) Density of oil approaching that of water, ( 3 marks)
(b) Low mixture temperatures, ( 3 marks)
(c) High pumping rate, ( 2 marks)
(d) Oil/water interface below test cocks. ( 2 marks)

23. With reference to centrifugal oil fuel purifiers explain : -
(a) Why the drive often incorporates a clutch, ( 3 marks)
(b) The possible causes of vibration, ( 2 marks)
(c) How the unit can be designed to be self cleaning and how this operation is made to be automatic ( 5 marks)

24. (a) Why are most centrifuges fitted with centrifugal clutched, ( 3 marks)
(b) Explain what part the gravity ring plays in separation. ( 4 marks)
(c) If on starting the centrifuge vibrates excessively what action should the operator take, and comment about the likely causes of the vibration. ( 3 marks)

25. (a) Sketch a static oily water separator, labelling all its important internal parts, ( 4 marks)
(b) Describe how it is intended to work. ( 3 marks)
(c) Explain the circumstances which would probably have the effect of reducing the separator efficiency. ( 3 marks)

26. (a) Explain how a discharge mechanism of a self-cleaning purifier bowl works.
(b) Comment on the problems that might occur if the self-cleaning system mal-functions. ( 4 marks)


REFRIGERATION
1. With reference to accommodation air conditioning plants explain :
(i) How uniform compartmental atmospheric conditions are maintained over a wide range of ambient atmospheric conditions, ( 6 marks)
(ii) Why the compartmental air conditions in (I) are confined within fairly close limits. (4 marks)
2. With reference to refrigeration plants state why :
(i) Refrigerant leakage imposes additional loading on the plant, ( 2 marks)
(ii) Excessive opening of the expansion regulator can cause severe icing at compressor suction, ( 3 marks)
(iii) Brine batteries need systematic 'de-frosting' to maintain effectiveness, ( 2 marks)
(iv) Although refrigerant contamination by oil is serious, water contamination is even more serious. ( 3 marks)

3. With reference to accommodation air conditioning plants explain why :
(i) Compartment temperatures tend to rise, ( 2 marks)
(ii) This temperature rise varies considerably from space to space, ( 2 marks)
(iii) Mechanical ventilation with air heating facilities is inadequate for comfort in ships operating between polar and equatorial ( 3 marks)
(iv) Air changes and compensation for air loss is essential. ( 3 marks)

4. (i) Draw a line diagram of an accommodation air conditioning plant labelling the principal items and showing the direction of air flow. ( 4 marks)
State how:
(ii) Accommodation air temperature is controlled, ( 2 marks)
(iii) Humidity is controlled within prescribed comfort limits, ( 2 marks)
(iv) Such an installation can contribute to the efficiency of ship's main plant. ( 2 marks)

5. (i) Sketch in diagrammatic form, a refrigeration unit operating on the vapour compression system ( 3 marks)
(ii) Describe how it operates and how adjustments can be made to its operating temperature. ( 3 marks)
(iii) What effect will the following have on its operation (a) high ambient temperature (b) gradual loss of gas, and (c) dirty heat exchanger. ( 4 marks)

6. Suggest with reasons the most likely cause of the trouble if the suction to a multicylinder refrigerant compressor is subject to considerable icing under the following simultaneously prevailing conditions :
(a) Compressor in good condition and running at normal speed, ( 3 marks)
(b) No detectable loss of refrigerant, ( 3 marks)
(c) No detectable loss of refrigerant, ( 2 marks)
(d) Brine temperature rising. ( 2 marks)

7. State with reasons why the following courses of action might be advisable if the temperature of the ship's cold lockers rises steadily although the refrigerant compressor runs continuously :
(i) 'de ice' exaporater, ( 2 marks )
(ii) 'top up' with refrigerant, ( 3 marks)
(iii) Clean both sides of condenser, ( 2 marks)
(iv) Overhaul compressor ( 3 marks)

8. Give reasons why each of the following conditions can result in excessive running of refrigerant compressors :
(i) High sea water temperature, ( 2 marks)
(ii) High atmospheric air temperature, ( 2 marks)
(iii) Leak in evaporator, ( 2 marks)
(iv) Air in refrigerant circuit, ( 2 marks )
(v) Fouling on water side of condenser, ( 2 marks)

9. With reference to refrigeration plants state how :
(a) Very low evaporator temperatures are achieved, ( 2 marks)
(b) Automatic expansion valves indirect expansion plants are adjusted, ( 2 marks)
(c) Compressors are protected against appreciable "carry over" of liquid refrigerant. ( 2 marks)
(d) Air in the system is detected, ( 2 marks)
(e) Over charge of refrigerant is indicated. ( 2 marks)

10. Briefly describe how in main refrigeration plants :
(a) Sea temperature can restrict plant operation
(b) The limitations in ( a) are overcome,
(c) Short cycling occurs,
(d) Short cycling is avoided ( 10 marks)

11. (a) Draw a line diagram of a cargo refrigeration plant provided for the carriage of refrigerated containers in one hold only, labelling the principal items and showing the directon of fluid flow in all lines and ducts, ( 2 marks)
(b) Explain how heat is extracted from the container contents and transferred to the condenser coolant,. ( 4 marks)

12. With reference to refrigeration plants define :
(a) Indications of refrigerant leakage, ( 3 marks)
(b) Steps to locate leak, ( 2 marks)
(c) Steps in refrigerant replenishment ( 3 marks)
(d) Indications of full charge restoration ( 2 marks)

13. (a) Explain the following terms with reference to air conditioning :-
(i) Wet bulb temperature
(ii) Dew point temperature
(iii) Relative humidity ( 3 marks)

(b) Itemize the preventive maintenance you would expect to be necessary on the automatic controls of an air conditioning plant with which you are familiar.

14. Sketch a section through the crankcase and pair of cylinders of a vee type refrigerant compressor indicating the direction of flow of refrigerant. ( 4 marks)
State why a compressor my 'short cycle' and how this condition is correct. ( 3 marks)
State why excessive 'icing up' may occur and how the compressor is protected. ( 3 marks)

15. In practice there is usually more than one possibility for nay particular symptom in a refrigeration plant. Give two reasons for each of the following in a freon system :
(a) High head pressure. ( 2 marks)
(b) Low head pressure. ( 2 marks)
(c) Compressor runs continuously ( 2 marks)
(d) Compressor runs nosily ( 2 marks)
(e) Compressor will not start (fuses have not blown and compressor will rotate). ( 2 marks)


Heat Exchangers
1. With reference to multitubular heat exchanges state why :
(i) Fresh water is generally preferred to sea water as a coolant. ( 2 marks)
(ii) Lubricating oil is generally maintained at a marginally positive head relative to the coolant. ( 2 marks)
(iii) Contra flow and multi pass arrangements tend to improve heat transfer rates for a given surface area. ( 3 marks)
(iv) Intermediate diaphragm plates make a useful contribution to tube life. ( 3 marks)
2. (i) Sketch a multi plate heat exchanger, labelling the principal components and showing the direction of fluid flow in all passages ( 5 marks)
(iii) Give three reasons tor plate relief putttern. ( 3 marks)
(iii) Explain why gasket thickness is critical. ( 2 marks)

1) With reference to multi tubular heat exchangers state why:
a) Fresh water is generally preferred to sea water as a coolant.
b) Lubricating oil is generally maintained at a marginally positive head relative to the coolant.
c) Contra flow and multi pass arrangements tend to improve hear transfer rates for a given surface area.
d) Intermediate diaphragm plates make a useful contribution to tube life.

2) (a) Sketch a multi plate heat exchanger, libeling the principal components and showing the direction of fluid flow in all passages.
(b) give three reasons for pleat relief pattern.
(c) explain why gasket thickness in critical.

3) With reference to multi tubular heat exchangers state why :
(a) the choice of tube material is only partially dependant upon its anti corrosive properties.
(b) the integrity of end cover division plates or diaphragms is of considerable consequence,
(c) heat transfer rates are only partially dependent upon circulating pump performance,
(d) parallel flow and single pass arrangements are effectively inferior to their contra flow and multi pass counterparts.

4) Describe how the following items are sometimes used to improve performance and condition of multi tubular heat exchangers:
(a) ferrous sulphate
(b) ultra violet lamps.

5) With reference to multi tubular salt water coolers:
(a) sketch a two pass cooler showing the direction of fluid flow
(b) give two faults to which it is prone,
(c) stte how these faults are countered.

6) With reference to multi tubular oil coolers define :
(a) Indications of tube leakage,
(b) reasons for tube failure,
(C) steps to locate a leak
(d) temporary corrective steps to stop leakage,
(e) permanent corrective steps to stop leakage.

7) Explain how the following conditions contribute to the satisfactory performance of multi tubular heat exchangers:
(a) tubes of approximately 15mm internal diameter and 17.5 mm external diameter.
(b) dense population in the tube nest.
(c) tube cleanliness,
(d) avoidance of low coolant flow rate through tubes,
(e) unimpeded passage of coolant at entry and exit from tubes,

8) (a) draw a line diagram of a vacuum type evaporation/distillation plant, labeling the principal items and showing the direction of flow in all lines.
(b) describe how it operates.
(c) state why the water may not be fit for human consumption.
(d) state how the water can be made fit to drink.

9) With reference to multi plate heat exchangers state why:
(a) fluid pressure and temperature does not normally exceed 10 bar and 1500 respectively,
(b) plates carry a relief pattern,
(c) plates are stainless steel and titanium whereas the tubes in multi tubular counterparts are non-ferrous,
(d) carrying bars are usually far loner than appears necessary,
(e) mass flow rate is not of major consequence.

10) Give reasons why the following actions might help correct the fault if an electric salinometer registers an unacceptable high value for the distillate from a vacuum evaporator:
(a) lower water level in evaporator.
(b) increase flow rate through brine pump,
(c) shut in coil inlet valve,
(d) shut in vapour valve
(e) give reasons why salinity should be maintained at a consistently low value.

11) State briefly what are the indications of, and the reasons for, the following malfunctions in single effect sea water evaporators:
(a) tendency to develop over pressure,
(b) tendency to prime,
(c) gradual reduction in continuous blowdown,
(d) gradual increase in distillate salinity.

12) Sketch a multi-plate heat exchanger showing how the plates are sealed.
(b) explain why working temperature and pressure can create problems in sealing, but differential expansion does not.
(c) state why carrying bars and clamping bolts appear unnecessary long.

14) (a) how would a leak in a lubricating oil heat exchanger of the tubular type be detected, it is cooled be sea water.
(b) explain how you would go about finding out the cause of the leak.
(c) if the leak was at the tubeplate expansion explain how you would rectify this fault.
(d) if the leak was due to the localized but deep pitting of a tube what other factors would you need to check.

14) (a) Draw a line diagram of a vacuum type evaporation/distillation plant using sea water feed, labelling the principal items and showing the direction of flow in all lines.
(b) If the salinometer is in-operable how can the purity of the water be assessed.
(c) Explain how by using the readings of sea water input and distilled water produced the brine density can be ascertained.

15) With respect to tubular heat exchangers :
(a) Describe two methods of allowing for differential expansion between tube and shell.
(b) The length of tube adjacent to the tube inlet is susceptible to failure for a number of reasons, discuss these.
(c) Describe a method of detecting tube leakage.

16) (a) If there has been a tube failure in an oil cooler how might this failure show itself.
(b) Explain, if the failure is in the tubeplate expansion, how the problem could be rectified.
(c) If the failure is due to pinholes in the tube itself how can the problem be rectified.
(d) Comment on the likely causes of (b)

Systems, Pumps, Etc.
17) (a) sketch a two stage centrifugal pump showing the direction of fluid flow.
(b) suggest with reasons a shipboard application for such a pump.
(c) State how and why the pump is kept flooded when not in use.
(d) State what effect discharge valve closure has on a running centrifugal pump.
18) (a) Draw a line diagram of a bilge pumping system for a dry cargo ship, labelling the principal items.
(b) Indicate the type and position of each valve fitted
(c) Explain how this system is protected against collision damage.
(d) Give reasons why the practice of endeavoring to draw the last vestige of water from the bilges with a centrifugal pump should be discouraged.

19) (a) Draw a line diagram of a central cooling system, labelling the principal items and showing the direction of flow in all lines.
(b) Describe how it operates.
(c) Define its advantages over the alternative installation of separate systems.

20) (a) Draw a line diagram of a fuel transfer and preparation system form bunker tank to boiler burner or engine fuel pump, labelling the principal items and showing the direction of flow in all lines.
(b) State why fuel is not usually transferred direct to service tanks from bunker tanks without first being held for a while in settling tanks.
(c) Define the safety measures incorporated if the system is to operate in a periodically unmanned condition.

21) With reference to self priming centrifugal pumps :
(a) Sketch a liquid ring priming pump,
(b) Explain how the priming pump in (i) operates,
(c) Explain why priming pumps are not fitted to all centrifugal pumps.

22) Identify the principal characteristics of the following pumps:
(a) Fixed stroke reciprocating,
(b) Variable stroke reciprocating,
(c) Single stage centrifugal,
(d) Gear
Select with reasons which of the listed pumps is likely to be most suitable for fuel transfer and supply duties.

23) In comparing centrifugal pumps employed for sea water circulation with those employed on other duties, explain why :
(a) Sealing ring clearances are coarser and less critical,
(b) internal inspections and overhaul is generally necessary at less frequent intervals,
(c) ancillary air pumps are of little value.

24) (a) Sketch a centrifugal bilge pump.
(b) Explain the particular need for priming such a pump,
(d) Give one advantage and one disadvantage of the centrifugal pump compared to the direct acting pump for bilge pumping duties.

25) (a) Sketch a direct acting, steam driven, reciprocating pump.
(b) Give a reason why it still finds acceptance for certain duties.
(c) Define these duties.

26) (a) Sketch a pump other than one of the reciprocating or centrifugal type.
(b) Explain how it operates.
(c) State with reasons the duty for which it is most suited.

27) (a) Sketch in cross section, a pump other than of the reciprocating, centrifugal, or gear type.
(b) Explain how it operates.
(c) Suggest with reasons a shipboard application for which it is well suited.

28) (a) Draw a line diagram of hydrosphere system (fresh water system incorporating an air reservoir) labelling the principal components and showing the direction of flow in all lines.
(b) Describe how a drop in pressure actuates the fresh water pump.
(C) state what advantages this system has over gravity head systems.

29) (a) Sketch a pump for handling hazardous chemical cargoes
(b) Describe how it operates.
(d) State how it differs from pumps handling crude petroleum cargoes.

30) (a) Draw a line diagram of a central priming system, labelling the principal components and showing the direction of flow in all lines.
(b) Describe how each pump is primed upon starting or loss of suction.

(d) State what advantages the system has over individual priming facilities.

31) Define how each of the following conditions can result in the 'fall off' in performance of centrifugal sea water circulating pumps:
(a) voyages in shallow coastal and estuarial waters,
(b) Voyages in ballast condition
(c) restricting flow by partial closure of suction valve,
(e) allowing pump to remain standing for long period with ship side suction valve open,
(f) allowing 'wear down' of pump bearings to become excessive.

32) By comparing the characteristics of the following pumps, deduce with reasons which one is best suited for the associated duty:
(a) heat exchanger sea water circulation -
Single stage centrifugal, multi stage centrifugal, direct acting reciprocating, crank driven reciprocating, positive displacement rotary,
(b) hydraulic power -
multi stage centrifugal, gear, screw, fixed stroke reciprocating, variable stroke reciprocating,
(c) noxious chemical cargo discharge -
Single stage centrifugal, multistage centrifugal, direct acting reciprocating, crank driven reciprocating, positive displacement rotary, gear, screw.

33) (a) Draw a line diagram of a fuel storage and transfer system labelling all the principal components.
(b) Indicate the type and position of each valve fitted, showing which valves can be operated from outside the machinery spaces.
(c) State how the system is protected against overpressure and overboard discharge.

34) (a) Sketch an independently driven man lubricating oil pump.
(b) Explain how it operates.
(d) Identify with reasons the clearances critical to pump efficiency.


Rudder
35) (a) Draw a line diagram of hydraulic power system for application other than steering gear in higher a chemical tanker, a 'roro' vehicular ferry, or a bulk carrier, labelling the principal items.
(b) Identify with reasons those parts of the system which are likely to give rise to trouble.
(c) Define the routine maintenance required to avoid trouble-free operation of the system over an extended period of time.
36) (a) Sketch a constant speed unidirectional, fixed stroke, radial type, rotary positive displacement pump for hydraulic power applications.
(b) Explain how it meets an infinitely variable demand in both directions.
(c) Given one important advantage it possesses over its variable stroke counterpart.

37) With reference to main fuel systems define the purpose of the following precautionary arrangements :
(a) duplication of settling tanks, pumps and heaters,
(b) safety devices on fuel lines,
(c) visual in supection capability of heater drains.

38) Suggest, with reasons, the most likely cause of the trouble if the performance of a centrifugal bilge pump has deteriorated to the extent that it will hardly empty the bilges under the following simultaneously prevailing conditions :
(a) pump running at normal speed,
(b) ammeter indicating slightly low current,
(c) all bilge valves, except one in use, tight shut,
(d) little evidence of air in system.

39) 39) with reference to main fuel systems define the purpose of the following precautionary arrangements:
(a) duplication of settling tanks, pumps and heaters,
(b) safety devices on fuel lines,
(c) Visual inspection capability of heater drains.

40) Suggest, with reasons, the most likely cause of ht trouble if the performance of a centrifugal blilge pump has deteriorated to the esxtent tht it will hardly empty the bilges under the folowing simultaneously preveiling conditions :
(a) pump running at normal speed,
(b) ammeter indicating slightly low current,
(c) all bilge valves, except one in use, tight shut,
(d) all strum boxes and strainers clear,
(e) little evidence of air in system.

41) (a) The vertical shaft of a centrifugal sea water pump has become worn in way of the packed gland to such an extent that sealing is becoming difficult.
(i) explain the factors which may have contributed to the excessive wear.
(ii)state one possible method of refurbishing the shaft
(b) Sketch a flexible packing unit suitable for a sea water pump and explain how it works.

42) (a) Describe clearly with the aid of a sketch, how a centrifugal bilge pump creates its own vacuum.
(b) What effect, if any, would you except from a centrifugal pump which due to its electric leads being incorrectly connected, was rotating the wrong way.

43) With reference to an electrically driven centrifugal sea water pump:-
(a) Give four reasons why the output may have fallen off.
(b) If the pump vibrates what could be the causes.
(c) Describe t test to prove the pump capacity.

44) (a) If a blilge pump has to be primed from the sea before being able to pump the bilge what is this a sign of.
(b) What forces the bilge water up the suction pipe into the pump casing.
(c) Make a sketch of an air pump suitable for a bilge pump and describe how it works.

45) (a) What is the inherent disadvantage of a packed gland for a pump.
(b) Sketch and describe a mechanical seal for a water pump showing the means used to cool and lubricate the seal and state the material of each component.
(c) Comment on the likely causes for malfunction of a mechanical seal.

46) (a) Describe with the aid of a diagrammatic sketch a fresh water system for a ship.
(b) If the water pressure was too low at the highest deck level describe in detail how you would go about rectifying this problem.

47) (a) Draw a line diagram of a fuel oil storage and transfer system indication valves and their type).
(b) Describe how the system is protected against overpressure and overboard discharge.
(c) How would you judge the rate at which you can take bunkers in a particular ship.

48) (a) Sketch a domestic fresh water system suitable for a reasonable sized ocean going cargo ship.
(b) One of the standard treatments for sterilizing dogmatic water on ships is to add chlorine, but if too much is added the water becomes unpleasant. Describe a suitable chlorine treatment unit with special reference to how the correct chlorine dosage is set and how it is maintained.
(c) State the quantity of chlorine the water should contain after the treatment, give your answer in p.p.m.

49) (a) Describe a suitable procedure for commissioning a hydraulic system.
(b) If initially a hydraulic system has been commissioned in an unclean state how is this likely to affect is operation.
(c) Identify the possible sources of contamination (assume the hydraulic oil supplied was clean)


Rudders, Steering Gears
50) (a) Describe a simple test to ensure that steering gear hydraulic telemeter systems are 'air free'.
(b) Define two ways whereby air enters such systems.
(c) Give reasons why it is essential that such systems be 'air free'.
51) with reference to hydraulic steering gears explain why :
(a) relief values are provided as well as shock valves,
(b) the pump is of constant speed, variable stroke,
(c) the ram glands are filled with soft or simple moulded packing.

52) With reference to hydraulic steering gears explain why:
(a) telemeter receivers are spring loaded,
(b) spring links are incorporated in the hunting gears,
(c)rudder movement is confined within port and starboard stops.

53) (a) Sketch a rotary vane steering gear.
(b) the pump is of constant speed, variable stroke,
(c) show how it is protected against shock,
(d) give a reason why more than four chambers are rarely provided.

54) (a) Sketch a constant speed unidirectional, variable stroke, axial type, rotary positive displacement pump for hydraulic power applications.
(b) state how it meets an infinitely variable demand in both directions.
(c) give one important advantage possessed over its radial stroke counterpart.

55) With reference to steering gears explain :
(a) how a limited amount of rudder 'drop' is accommodated,
(b) why alternative means of operating the gear is obligatory,
(c) Why maximum angular movement of the rudder is generally limited to a comparatively moderate angle port and starboard.

56) (a) Draw a line diagram of hydraulic power system for application other than steering gear in either a chemical tanker, a 'roro' vehicular ferry, or a bulk carrier, labelling the principal items.
(b) Identify with reasons those parts of the system which are likely to give rise to trouble.
(c) Define the routing maintenance required to avoid trouble-free operation of the system over an extended period of time.

57) with reference to hunting mechanisms associated with large steering gears:
(a) sketch any selected arrangement,
(b) give reasons for its incorporation in steering gears,
(c) state what periodic attention is required,
(d) define thepurpose of the spring link.

58) with reference to ram steering gears explain how:
(a) shock loading is absorbed,
(b) rudder position corresponds to the helm position at all times,
(c) rudder 'drop' is accommodated,
(d) steering gear can be operated upon failure of the bridge telemeter system.

59) Explain why the following leakage in hydraulic steering gears demands immediate attention :
(a) pipe connections in telemeter system.
(b) pipe connections in power system
(c) shock/by-pass valves,
(e) power pump glands.

60) Give reasons for the following faults in ram steering gears:
(a) in spite of purging the telemeter system before the voyage, the gear has developed an increasing tendency to wander,
(b) noticeable sluggishness after a period of heavy weather,
(c) excessive and persistent hunting.

61) (a) sketch a hunting gear as fitted to a hydraulic steering gear labelling the principal items.
(b) explain the purpose of the hunting gear.
(c) state how worn pins in the hunting gear effect steering gear operation.

62) With reference to ram steering gears explain :
(a) the purpose of the Rapsom slide.
(b) why the minimum number of rams is two,
(c) how a four ram gear can be operated on two rams only,
(e) what precautions are to be observed under conditions in (iii)

63) (a) Draw a line diagram of a hydraulic telemeter system for a ram steering gear, labelling the principal items and showing in detail both the transmitter and receiver.
(b) explain why the receiver, is spring loaded.
(c) State why the system must be maintained completely free of air.
(d) give two reasons why the oil level in the replenishment tank should be checked at regular, fairly frequent, intervals,

64) with reference to electro hydraulics steering gears explain how the ship can be steered in each of the following circumstances :
(a) destruction by fire of primary supply cables,
(b) destruction by fire of telemeter lines,
(c) bearing failure in running pump

65) (a) Draw a line diagram of the hydraulic system for a ram steering gear, labelling the principal items.
(b) Describe how the cushioning and relief arrangements function.
(c) bearing failure in running pump.

66) (a) draw a line diagram of the hydraulic system for a ram steering gear, labelling the principal items.
(b) Describe how the cushioning and relief arrangements function.
(c) state with reasons how piston and cylinder wear in the pump effects the action of the gear.

67) With reference to rotary wane steering gear state:
(a) how the fixed vanes are attached to the cylinder,
(b) how the moving vanes are attached to the rotor,
(c) how strength is imparted to the moving vanes to enable them to act as rudder stops,
(e) how rudder uplift is accommodated.

68) (a) make a simplified sketch of a rotary vane steering gear labelling the principal components and identifying he manifolds for port and starboard movement.
(b) describe how it operates,
(c) explain how the vanes and chambers are sealed.

69) (a) Itemize the checks you would carry out on a hydraulic steering gear before leaving port.
(b) Describe how you would fill the hydraulic system with a new charge of oil (assume this operation is to be done in port).
(c) List the usual contaminants found in a steering gear oil system and describe the faults that ONE containment might cause.

70) (a) Explain the principle of a hydraulic telemotor.
(b) Explain with the aid of a sketch how the hydraulic pump on a steering gear is designed to accommodate reversal of flow.
(c) How does air sometimes get into a steering gear hydraulic system.

71) With reference to steering gears :-
(a) Discuss why connecting bolts between the upper and lower rudde stock are susceptible to slackness and damage.
(b) If the bolts mentioned above were found to be slack what action and checks would you suggest.
(c) If a pintle bearing is found to be considerably worn, apart from renewing the bearing, what other factors would you check.

72) You have been sent as second engineer on a ship which has been laid up for some months which now is to be brought back in services :
(a) Itemise the checks you would carry out on the steering gear, which is of the 4 ram 2 pump unit type.
(b) If the steering gear seemed to function considerably slower when using one particular pump unit, discuss the possible reasons for this.


Shafting & Bearings
73) (a) Describe how unequal loading of main transmission shaft bearings may be partially corrected at sea.
(b) Suggest, with reasons, what remedial action should be taken upon arrival in port.
(c) Define the indications whilst at sea that unequal loading of such bearings exists.
74) (a) Sketch a coupling enabling external withdrawal of propeller shafts.
(b) Give a general description of the coupling.
(c) Give one advantage and one disadvantage of this coupling compared to the solid flange type.

75) (a) Sketch a bearing carrying large diameter main transmission shafting.
(b) Explain how the bearing is lubricated and cooled.
(c) Give two reasons why such bearings occasionally overheat.

76) (a) suggest with reasons the effect long voyages in ballast may have or main transmission shaft coupling bolts.
Give reasons for the following actions when an overheated main shaft bearing is :
(b) Closely watched but left in service, unless in danger of wiping,
(c) Adjusted, even whilst on passage.

77) (a) Sketch any type of flexible coupling for main propulsion drives.
(b) Explain its operation.
(c) Explain how such a coupling can become defective.

77) With reference to main transmission shaft bearings state how:
(a) 'wear down' is measured,
(b) adjustments are made if 'wear down' is excessive,
(c) a 'wiped' bearing is make serviceable.

78) With reference to main thrust blocks:
(a) identify the critical clearances and state why they are critical,
(b) describe with detail sketches how these clearances are adjusted,
(c) give a reason why such bearings sometimes overheat although the clearances are adequate.

79) With reference to main transmission shaft coupling bolts state :
(a) Why fitted blots are used exclusively rather than clearance blots with dowel pins,
(b) why excessively tight bolts should into be forced into the couplings,
(c) Why excessive tightening of coupling bolts should be discouraged,
(d) what is the major disadvantage of using fitted blots in these couplings.

80) (a) Sketch a sealing arrangement for an oil lubricated stern tube.
(b) Identify the common forms of seal failure.
(c) State how oil loss due to seal failure can be restricted whilst on passage.

81) With reference to main thrust blocks state why :
(a) cooling coils are sometimes fitted in the sumps,
(b) many are self lubricated, that is, independent of main Lubricating oil system.
(c) axial clearance between collar and pads is minimal,
(e) they occasionally overheat,
(f) they are generally located in close proximity to the main engine rather than the propeller.

82) (a) Describe how propeller shaft/stern bearing clearance is measured.
(b) Identify with reasons the major factors which substantially determine the range of permissible clearance.
(c) State with reasons what parts of propeller shafts should receive particularly close inspection upon withdrawal of such shafts for survey.
(d) State why some propeller shafts require less frequent inspection that others.

83) Explain how the following conditions generally result in the fretting of main transmission shaft coupling bolts.
(a) excessive force required to drive home bolts due to excessive tightness of blots in holes,
(b) slack fit of bolts in holes,
(c) nuts not tightened up sufficiently.
(d) poor alignment of shafting,
(f) shafting continuously subject to severe propeller vibration.

84) (a) Sketch a hydraulic coupling between a medium speed diesel engine and reverse/reduction gear.
(b) Describe how it operates.
(c) State what advantages such couplings have over their friction, powder and magnetic counterparts.

85) (a) Describe the 'Pilgrim Wire' method of checking alignment of main shafting.
(b) Explain how the readings are recorded and interpreted.
(c) afloat without cargo,
(e) afloat with full cargo,
(f) in dry dock.

86) Give reasons why the following conditions can cause vibration in main transmission shafting :
(a) ship in ballast,
(b) poor cargo distribution,
(c) damaged propeller blades,
(d) propeller operating in critical speed range,
(f) main engines working on overload.

87) Define, in each case, the conditions under which each of the following courses of action might be considered appropriate, upon the running temperature of a main transmission shaft bearing reaching and remaining at an unacceptably high level:
(a) check condition of adjacent bearings,
(b) flush bearing through with oil or a mixture of oil and soft soap,
(c) reduce shaft revolutions and hose bearing,
(d) stop ship and adjust bearing.

88) while inspecting the tailshaft after withdrawal from stern tube a crack is found in the non-ferrous liner:
(a) How important is this crack and why ?
(b) How would you determine the true extent of the crack.
Tailshafts are susceptible to cracks, give reasons for this.

89) (a) Describe with the aid of a sketch the construction of a single collar thrust bearing.
(b) Explain the principle on which it works.
(c) Explain how you would take the essential clearances and explain the significance of them.

90) (a) Why is the axial clearance of a main thrust bearing an important dimension.
(b) How is this clearance measured.
(c) Describe how the thrust pads are removed for inspection and state what you would look for in particular.

91) (a) What are the advantages of a propeller shaft with its after end flanged compared with a shaft with flange in-board.
(b) With reference to a stern bering, describe how seals are prevented from causing grooves in the shaft.
(c) Describe with the aid of a sketch, how a stern tube is held into the stern frame, and give details of how the tube can be designed so that some alignment adjustment is possible.

92) (a) What are the likely results of running machinery not properly lined up.
(b) Explain THREE methods of lining up an electric motor with a horizontal spindle centrifugal pump.
(c) What factors prevent absolute accuracy in (b)

93) With reference to main thrust blocks explain why:
(a) although the shaft collar runs against the ahead pads for most of the ship's life, yet the total axial clearance between the collar and both sets of pads seems unnecessarily small,
(b) although the trust block housing is of heavy construction, yet unacceptable axial movement of the main transmission shafting is sometimes experienced.
(c) location is as near the main propulsion machinery as possible,
(d) pads are not normally arranged in a full circle around the collar,
(f) journal bearings are incorporated fore and aft of the collar.

94) (a) Sketch a stern seal arrangement installed in association with an oil lubricated stern tube or stern bearing, identifying the various components of the seal.
(b) State how ingress of sea water into the stern tube is prevented.
(c) Describe the corrective action possible whilst the vessel is afloat, should the seal fail to remain tight.
State why two stern seal oil header tanks are fitted in some instances.

95) (a) Give THREE possible reasons for excessive loss of lubricating oil from the stern gland seal system.
(b) Outline the appropriate courses of action that should be taken in order to eliminate or reduce the effect of this loss.

96) (a) What is the purpose of the main thrust bearing.
(b) When checking the main thrust bering, what dimensional checks would be necessary.
(c) How is a thrust bearing cooled.
(d) Describe, with a sketch, the special chocking arrangements normal to thrust bearing.

97) (a) Main transmission shaft bearings occasionally overheat, give reasons why this happens.
(b) What can the ships engineer do to overcome this over-heating problem.
(c) Describe a monitoring system for a shaft bearing.


CONTROL
98) (a) Describe with sketches a method of remotely indicating the contents of a tank.
(b) Assess the accuracy of the method described.
(c) State how accuracy may "fail off"
(d) State how accuracy may be restored.
99) With reference to auxiliary engines describe transducers suitable for producing either electrical of pneumatic signals to indicate :
(a) Lubricating oil pressure,
(b) jacket cooling water temperature.

100) (a) Sketch a diaphragm operated control valve of any design.
(b) State how load changes are sensed.
(c) State how command signals re transmitted to actuators.

101) (a) Describe two different methods for the remote measurement of fluid flow through a pipe.
(b) Compare the accuracy of the methods.
(c) Give one cause of error in each method.

102) (a) Sketch two arrangements for determining remotely the quantity of liquid in tanks.
(b) Compare the accuracy of these methods.
(c) Describe how the signals are converted and fed into an automatic recording and control

103) (a) Explain how the condition of air used in pneumatic control systems is kept within closely defined limits.
(b) State what routine maintenance and tests are needed to keep the system fully operational.
(c) State why independent compressors are preferable to bleeding from main or auxiliary starting air reservoirs.

104) (a) Sketch a pneumatically controlled valve for maintaining a constant pressure in steam or air ranges.
(b) Explain how it operates.
(c) state how the valve differs for steam or air services.

105) (a) Sketch a differential pressure alarm fitted across an oil filter.
(b) Explain how it operates.
(c) State how it can be tested whilst the filter is on service.

106) Describe transducers for producing electrical or pneumatic signal to indicate:
(a) Lubricating oil pressure of auxiliary diesel engines,
(b) Exhaust temperatures of same engines.
(c) State how each of these transducers can be tested.
(d) Explain how an alarm is energized if either the pressure or an exhaust temperature goes outside the set limits.

107) (a) Sketch a pneumatically operated valve for regulating coolant flow.
(b) Explain how instantaneous valve position is regulated.
(c) State how valve position is indicated at the console.

108) (a) Sketch an arrangement for indicating propeller shaft speed at a position remote from the shaft.
(b) Explain how it operates.
(c) State how, with this system, inaccuracies occur and are kept to a minimum.

109) Describe with sketches circuit transducers for producing electrical or pneumatic signals to indicate :
(a) main lubricating oil pressure,
(b) cylinder jacket cooling water temperature,
(c) state how each transducer is tested.

110) With reference to pneumatic control systems explain why:
(a) filters re fitted to compressor suctions,
(b) filters and separators are fitted between compressors and air receivers,
(c) filters and dryers are fitted between receivers and air mains.

114) With reference to direct expansion refrigeration plans used in conjunction with ships' stores lockers:
(a) sketch an automatic expansion valve with thermostatic control,
(b) describe how it operates,
(c) explain with sketches how the temperature sensitive element located in the lockers controls the circulation of refrigerant.
115) (a) state why a pneumatic control system requires clean dry air.
explain how the following pollutants are dealt with :
(b) water
(c) oil
(d) dust and dirt.

116) (a) Draw a line diagram of an arrangement whereby the pressure of oil delivered to a main lubricating oil system by a constant speed, positive displacement, pump is pneumatically controlled within set limits.
(b) Trace the sequence of events resulting from deviation in oil pressure.
(c) State why a control valve is used to preference to altering pump speed.

117) (a) Draw a line diagram of a control system to operate widely distributed valves from one station, labelling the principal components
. (b) Describe how any one valve is remotely manipulated.
(C) Explain how the condition of all valves can be ascertained at any time.
(d) Suggest with reasons a shipboard application of such a system.

118) Describe with sketches a device giving audible and visual alarm under either of the following conditions.
(a) burst fuel pipe,
(b) overheated bearing in main machinery.

119) (a) Sketch a pneumatic controller employing the nozzle/flapper principal.
(b) Explain why a restrictor is fitted in the air supply line.
(c) State why the diameter of this restrictor is smaller than that of the nozzle orifice.
(d) Describe how the controller is checked for accuracy.

120) (a) Sketch a diaphragm operated control valve of any design.
(b) State how flow changes are sensed.
(c) State how command signals are transmitted to actuators.

121) (a) Describe with sketches a bridge/engine room telegraph interconnecting gear.
(b) Explain the how the system may operate a "wrong way" alarm.

122) Describe with sketches instruments used for measuring the ambient temperature in the following spaces :
(a) refrigerated compartment.
(b) main machinery exhaust gas uptakes.

123) with reference to a control system :
(a) what are the signs of an unstable system.
(b) Choose a system with which you are familiar and itemise the checks you would make to determine "the cause of instability.

124) With reference to a large air operated control valve of the diaphragm type
(a) Explain how the length of stroke can be altered.
(b) Explain how the speed of opening (or closing) is changed.
(c) Describe how the position of the valve i.e. 'open' or 'closed' can be led to a monitoring station.

125) (a) Bridge control of main engine speed is now common, describe such a system with the aid of sketches if necessary.
(b) How is this system checked before leaving port.
(c) How can the engine room staff over-ride bridge signals if necessary.

126) (a) Sketch a pneumatically operated diaphragm control valve with a double valve/double seat arrangement, and itemise the main parts.
(b) Explain why a moulded diaphragm is advantageous as far as control is concerned.
(c) What are the advantages of a double valve compared with the single valve design.

127) Explain the automatic controls of a sea water evaporator so that is can be part of the UMS mode. Your answer which should be complete with diagrammatic sketch should cover output, brine density, brine level and the purity of made water.
(a) Sketch a closed loop control system, identify the three basic parts, and describe how the system works.
(b) Describe how the closed loop system is used in the control of an a.c. generator.

128) (a) Make a diagrammatic sketch of a salinometer which would be suitable for a sea water evaporator.
(b) Describe how this instrument works.
(c) List three common faults with regard to accuracy of reading.

129) The measurement of oxygen in an exhaust gas can be most helpful in assessing combustion efficiency but its measurement for an enclosed space about to be entered is critical for human safety.
(a) Describe the principles of an oxygen meter.
(b) How is the meter's calibration checked.
(c) How can false readings occur.

130) (a) Describe with the aid of a sketch a suitable means of remotely gauging the depth of liquid in a tank.
(b) What factors can influence the accuracy of the reading.

131) (a) Sketch in block form a 'closed loop' and also an 'open loop' control system.
(b) Describe the controls you would expect to find on a fuel oil separator plant designed to operate fully automatically.

132) With reference to a control system :
(a) Comment on why it may become unstable.
(b) Choose a system with which you are familiar and itemise the checks you would make to determine the cause of

133) Describe with the aid of sketches the principle of operation of the following instruments:
(a) tachometer
(b) pyrometer
(c) floweret

134) Itemise the principal causes of irregular operation of a pneumatic diaphragm operated reducing valve and how they are remedied.

135) With reference to a pneumatic control system sketch and describe the following :
(a) drier
(b) filter
(c) automatic compressor drain
(d) automatic stop/start.

136) With reference to automatic control explain the meaning of five of the following terms :
(a) Closed Loop
(b) Reference input signal
(c) Dead band
(d) Deviation
(e) Gate
(f) Address

137) Remote control of main machinery is now very common and with this in mind explain :
(a) how the number of automatic and consecutive attempts which fail to start are limited.
(b) the system of interlocks which prevent simultaneous control from bridge and engine room.
(c) the starting air system is provided with an alarm, what is the significance of the pressure at which the alarm is set.


Materials
138) Give two desirable and two undesirable properties of the following metals:
(a) brass,
(b) cast iron,
(c) mild steel,
(d) for each metal give a preferred marine engineering application.
139) (a) State why the properties of mild steel make it suitable for many marine engineering purpose.
(b) State why the tensile strength of steel cannot be increased without decreasing the malleability, ductility and weldability.
(c) Give two instances in marine engineering where the physical properties of steel are modified by alloying, giving reasons for this modification.

140) By comparing the physical properties and metallurgical compositions of the following metals deduce with reasons which one is best suited to the associated application :
(a) reduction gear pinion -
mild steel, nodular cast iron, monel metal, gun metal, nickel- chrome steel, muntz metal.
(b) gas or steam tubine blade for service temperature in excess of 5000C -
mile steel, phosphor bronze, monel metal, stainless steel, nickel-chrome steel, brass,
(c) tube of sea water cooled oil cooler -
mild steel, phosphor bronze, muntz metal, stainless steel, titanium, aluminium bronze, copper.

141) By comparing the physical properties and metallurgical compositions of the following metals, deduce with reasons which one is best suited for the associated duty:
(a) auxiliary diesel engine pistons- cast iron, cast steel, aluminium,
(b) condenser tubes - brass, aluminium bronze, stainless steel.

142) Outline THREE main requirements of a material used in the construction of a pressure vessel.
(a) State ONE material used in the construction of the vessel.
(b) Explain how a welded joint could cause failure of the vessel.

143) Suggest a typical shipboard machinery application for each of the following metals and explain how their properties make them particularly suitable for the stated application :
(a) stainless steel,
(b) grey cast iron
(c) aluminium bronze,
(d) monel metal,
(f) cupro nickel.

144) By comparing the physical properties and metallurgical composition of the following metals, deduce with reasons which one seems best suited for the associated duty :
(a) safety valve or relief vale spring -
minckel-chrome steel, chrome-molydenum steel, stainless iron, monel metal, forged steel, cast steel, silicon-manganese steel,
(b) refrigerant condenser tubes -
monel metal, stainless steel, copper, aluminium brass, phosphor - bronze, cupro nickel, mild steel,
(c) main shaft plain bearing -
phosphor bronze, babbitt metal, copper, lead, mild steel, brass, cast iron.

145) (a) Describe a method of tracing a crack that is only partially discernible to the naked eye.
(b) Explain how propagation of such a crack can be arrested.
(c) Describe a cold process of repairing cracked machinery components 'in situ'.
(d) Give a disadvantage of the method described.

146) (a) outline two main properties of materiel used for the construction of diesel engine crankshafts.
(b) State two crank shaft materials.
(c) Outline two reasons why one of these materials might be used in preference to the other.

147) With reference to welding :
(a) Comment on the basic difference between not and cold cracking and explain how ductility is an important factor.
(b) Draw a simple sketch showing 'undercut' and give two reasons why it occurs.
(c) What effect may result from using damp electrodes and now can this be avoided.


LUB OILS
148) The report on a lubricating oil sample gave the following details :
High acidity,
High sediment content,
Excessive water content,
Appreciable dilution by medium distillate fuel
(a) Define possible causes for each condition mentioned.
(b) State why fuel dilution is undesirable.
149) The specifications for two liquid fuels are as follows:
(a) (b) Specific gravity 0.942 0.981
Viscosity (c St) 120 365
Pour point (0C) 9.8 35.2
Vanadium (ppm) 120 90
Sulphur (%) 3.2 4.9
Carbon residue (%) 8.2 10.4

(a) Suggest with reasons the application for which (a) is likely to be most suitable.
(b) Suggest with reasons the application for which (b) is likely to be most suitable.
(c) Define the significance of the sulphur % as given for each fuel application.

150) Describe how it is determined whether lubricating oil deterioration is due to contamination by :
(a) fuel oil,
(b) fresh water,
(c) sea water,
(d) combustion products.
(e) state why lubricating oil constitutes a particularly dangerous fire hazard.

151) With reference to fuel for either motor or steam propulsion :
(a) specify the chemical constituents of the fuel selected,
(b) identify the impurities in the fuel and the compounds formed upon combustion,
(c) describe the effects of the compounds in (ii) on plant operation and maintenance.

152) (a) Specify with reasons where test samples should be drawn from a main lubricating oil system.
Describe shipboard tests to determine:
(b) water content,
(c) acidity,
(D) suspended solids.
(e) flash point

153) (a) State how and why lubricating oil deteriorates in main lubrication systems.
(b) State how deterioration becomes apparent.
(c) Describe simple shipboard tests to determine the degree of contamination.

Give a reason in each case, why each of the following conditions of lubricating oil is unacceptable :
(d) high acidity,
(e) significant fuel contamination,
(g) significant fresh water contamination.

154) (a) Draw a line diagram of a lubricating oil storage, settling, replenishment and purification system as far as the main lubricating oil pump, labelling the principal items and showing the direction of flow in all lines.
(b) Explain why setting and purification facilities are provided.
(c) State why reserve capacity is provided.

155) (a) Give reasons why cleanliness is so important for hydraulic systems.
(b) Explain how a system, which was originally quite satisfactory, can become contaminated, even though any make up added has been pure.
(c) What are the usual signs of contamination.

Fuel Oils
156) (a) Suggest with reasons which of the following data is relevant and significant to the quality of fuel oil.
Viscosity,
Pour point,
Closed flash point,
Open flash point,
(b) Define the significance of lower and higher calorific value in assessing the standard of liquid fuel.
157) (a) State why it is necessary to control the temperature of heavy distillate fuel within close limits before burning.
(b) Define the effects of allowing the oil temperature to vary outside these limits.
Describe the tests to evaluate the following properties of liquid fuel:
(c) viscosity,
(d) closed flash point.
Account for any inaccuracies in the tests.

158) (a) Identify the factors which may limit the speed at which bunkers may be taken on board.
(b) Describe a system with specific reference to preventing over flows.
(c) Describe an automatic alarm suitable for fitting into a bunker tank to signal that the tank is practically full.


Feedwater, Etc
159) Give a typical analysis of the dissolved solids in a sample of :
(a) fresh water,
(b) Sea water
Identify contaminants forming:
(c) soft scale,
(d) hard scale,
(e) initiators of corrosion.
160) (a) Suggest with reasons which four of the following impurities in the feed water of a 'package' boiler operating at 7 bar, dry saturated, are likely to contribute most to scale formation :
silica,
iron compounds,
sodium chloride,
magnesium bicarbonate,
calcium bicarbonate
calcium sulphate
soidum sulphate
magnesium chloride.
(b) Define briefly the water treatment required to ensure the precipitation of scale in a soft form.

161) with reference to water made by a distillation plant, which is to be used for drinking purpose.
(a) what further treatment is necessary to ensure biological purity.
(b) How is the treatment mentioned in (a) controlled.
(c) Distilled water is usually 'flat' to the taste, how can this be improved.
(d) How is the purity of water taken on board from a shore supply checked for purity.


Fires and explosions
162) With reference t diesel engine driven emergency fire pumps :
(a) define their limitations as regards suction lift,
(b) explain how and why they are isolated from the main fire pumps,
(c) state how such pumps are primed,
(d) define the conditions under which such units would be used.
163) (a) Draw a line diagram of a multi bottle carbon dioxide fire smothering installation excluding the spaces covered.
(b) Describe how gang release functions.
(c) State what action is necessary if the gang release fails to operate.

164) (a) Give two possible causes of electrical fires at switchboards and in electrical machines and wiring.
(b) Describe how a large electrical fire can be quickly controlled.
(c) State how the risk of electrical fires can be reduced.

165) State what precautions need to be observed in order to avoid or contain an outbreak of fire arising from the presence and use of the following equipment aboard a vessel afloat at a repair berth :
(a) electric are welding equipment,
(b) acetylene and oxygen bottles and hoses,
(c) temporary lighting and wandering power cables,
(d) flammable liquids, paints and varnishes,
(e) cotton waste and rags.

166) With reference to a ship's firemain explain how :
(a) provision is made for an alternative supply of water in the event of failure of the engine room fire pump,
(b) integrity of the main is maintained in the event of destruction of the main within the machinery spaces,
(c) damage to the main can be avoided in sub zero atmospheric conditions.

167) With reference to fire smothering system ;
(a) differentiate between the nature and manner of extinction of chemical and mechanical foam,
(b) describe with line sketches a mechanical foam system covering the machinery spaces,
(c) specify the routine testes applied to ensure full operational capability of system (ii) at all times.

168) (a) Suggest with reasons the principal causes of fire in accommodation and service spaces both at sea and in port.
(b) Sketch a fire detector commonly used in conjunction with a alarm belt circuit.
(c) State how compensation is made for a slow change in ambient temperature.
(d) explain why fire my spread more rapidly in a ship under repair in a yard than when at sea.

169) (a) Sketch in detail a portable carbon dioxide fire extinguisher.
(b) State why the tare weight is marked on the body.
(c) Suggest with reasons, for which fires it is most suitable.
(d) Suggest why in certain circumstances it can be fore of a hazard than a help in untutored hands.

170) With reference to fixed carbon dioxide fire smothering systems explain :
(a) how rupture of the bursting disc on a gas cylinder does not result in loss of gas,
(b) Why the nozzles are generally distributed well down in the machinery spaces but not in cargo spaces.

171) Give reasons why fires occasionally occur in each of the following localities :
(a) boiler flats high up in the machinery space,
(b) purifier flats,
(c) engine exhaust trunking,
(d) define the means employed in each case for extinction and prevention of reignition.

172) (a) Draw a line diagram of s sprinkler system, labelling the principal components and showing the direction of flow in all lines.
(b) Describe how it operates in the event of a minor fire in a small compartment.
(c) State how operation differs in the event of a major fire in a large compartment.

173) (a) Draw a line diagram of a firemain serving both deck and accommodation spaces, labelling the principal items.
State how an uninterrupted supply of water is still maintained under each of the following conditions :
(a) failure of the engine room fire pump,
(b) destruction of the engine room firemain,
(c) vessel assuming a servere list.

174) State with reasons what types of fire each of the following portable extinguishers is likely to be most effective in extinguishing.
(a) soda-acid
(b) dry powder
(c) carbon dioxide
(d) foam
(e) State why(d) needs occasional recharging although it has not been used.

175) state how and why the following equipment is shut down during a major fire which has necessitated the evacuation of the machinery spaces :
(a) settling and service tank valves,
(b) fuel transfer and supply pumps,
(c) mechanical and natural ventilation
(d) State how the fire is brought under control using the facilities available outside the machinery spaces.

176) Describe how outbreaks of fire in the following instances can be extinguished : (a) bales of cotton waste or similar material in store rooms,
(b) bagged flammable powders in cargo bolds,
(c) oil fuel spills on boiler flats,
(d) suggest with reasons why (c) is potentially the most dangerous situation.

177) (a) Describe with sketches any one of the following portable fire extinguishers:
Chemical foam,
Carbon dioxide,
Dry powder,
(b) Suggest why n certain instances carbon dioxide and dry powder can be more of a hazard than a help in untutored hands.
(c) Suggest why dry powder is possibly more effective than carbon dioxide for switchboard fires,
(d) State why chemical foam extinguishers occasionally require recharging even though they have not been used.

178) Identify with reasons which of the following courses of action would be advisable and which ones would not be advisable if a firm has filled the accommodation with thick acrid smoke :
(a) use all means available to disperse smoke (main ventilation, portable exhauster fans and ducting) before entering with water hose,
(b) seal accommodation off from the atmosphere and inject carbon dioxide through a vent opening,
(c) dispatch a person wearing a smoke helmet into the accommodation with a hose or portable extinguisher,
(d) dispatch two persons wearing self contained breathing apparatus into the accommodation to reconnoitre and report back,
(e) allow all smoke emitting combustibles to burn away before going in to tackle the fire.

179) (a) Draw a line diagram of a complete inert gas system incorporating an autonomous gas generator, labelling the principal items and showing the direction of fluid flow in all lines.
(b) describe briefly how optimum quality of gas is achieved,

180) (a) Draw a line diagram of a carbon dioxide, bulk storage, fixed fire smothering installation, labelling the principal items and showing the direction of flow in all lines.
(b) list the safety devices built into the installation.

181) (a) Draw a line diagram of a fire smothering and tank inerting system using gas from the main uptakes, labelling the principal components and showing the direction of flow in all lines and ducts.
(b) Describe the scrubbing process and state its purpose.
(c) State what safety devices are incorporated in the system.

182) Suggest with reasons which one of the following extinguishers seems Best suited for engaging the associated fire :
(a) local but intense oil fire on tank tops -
water hose (jet or spray), portable carbon dioxide, dry powder, soda acid, portable foam,
(b) accommodation fire in cabin -
portable carbon dioxide, soda acid, dry powder, water hose, carbon tetra chloride.

183) Suggest with reasons which ONE of the following extinguishers seem best suited for engaging the associated fire :
(a) large pan of fat blazing fiercely on hot galley stove-water nose (jet or spray), dry powder, portable foar, portable carbon dioxide,
(b) electrical insulation smoldering behind 'dead front' switchboard
- fine water spray, portable foam, soda acid. Dry powder,
- portable carbon dioxide.

184) (a) Describe with the aid of a single block sketch an inert gas system for a tanker.
(b) What should happen to the system if the oxygen content of the gas rises to an unacceptable degree.
(g) Explain why inert gas systems are so prone to corrosion attack.

185) On taking over as second engineer on a ship which has been laid up for some months : (a) itemise the checks you would carry out on the multi-bottle CO2 fire extinguishing system.
(b) How would you assess the state of the portable fire extinguishers in the engine room.
(g) What other items concerning fire fighting you need to check.

186) (a) Explain the conditions usually associated with spontaneous combustion, and give one example of how this type of fire might occur in an engine room.
(b) The use of paints, varnishes and glues may constitute a fire hazard , explain why this is so and describe how this risk may be reduced.
(c) State FOUR ways in which a ships engineer can significantly reduce the risk of fire in an engine room. Ignore the risks mentioned in (a) and (b)

187) (a) Describe in detail how you would completely check a CO2 fire extinguisher system which is of the multi-bottle type.
(b) State when you would prefer to do this check i.e. at sea or in port and give your reasons.

188) (a) Engine room fires usually result in enormous quantities of smoke, why is this.
(b) Why is this smoke in some ways more dangerous than the fire itself.
(c) How can this smoke from a fire be controlled.

189) Assuming that a serious fire has started on the top of a diesel generator : (a) What are the most likely causes of the fire.
(b) Itemise the important steps you should take in some order of priority.
(c) What will be, almost certainly, the immediate consequences of this type of fire.

190) (a) Sketch a 'gang release' CO2 system.
(b) Why are the larger CO2 systems designed for 'gang release'.
(c) Make a sectional sketch through the top of a CO2 bottle clearly showing how the rotation of the release handle allows the CO2 to flow to the manifold. All items should be named.

191) (a) Sketch a sprinker system suitable for protecting an engine room space on a large ocean going cargo vessel.
(b) Explain how the 'section alarm' and 'test circuit' systems work.

192) (a) Why are special precaution often taken with regard to fire risks of oil separators.
(b) Describe in detail how the risks can be reduced.


Insulation Resistance
192) (a) State the reason for carrying out insulation tests on electrical machinery.
(b) Explain how insulation test readings are recorded and interpreted.
(c) Briefly describe the principle of operation of an insulation testing device.
193) (a) State the effect which temperature has on the insulation resistance of electrical machinery.
(b) Explain why the insulation resistance of an idle electrical machine is at greater risk of determoration than that of a continually running machine.
(c) Describe a procedure for carrying out systematic checks on the insulation resistance of an electrical machine.

194) (a) Explain how the insulation resistance of a material can be measured.
(b) Describe the factors affecting insulation resistance.
(c) Describe a procedure for testing and recording the insulation resistance of an electric motor.

195) With reference to a.c. portable appliances aboard ships :
(a) Explain why the risk of electric shock is greater than that associated with fixed electrical installations.
(b) Briefly explain how a 115 V supply from a transformer can be adapted to limit the shock risk to personnel to a maximum of 60 V and state why this voltage limitation is considered necessary.
(c) Briefly describe the conditions which can increase the dangers of electric shock tc personnel and state the effect those conditions have on the human body.

196) (a) State why it is necessary to dry out electrical machinery after accidental immersion in water.
(b) Describe a method of drying out the windings of an a.c rotor stating any precautions that should be taken.
(c) Describe a suitable procedure for putting back into service an electrical machine which has been subjected to a drying process.

197) (a) Briefly describe the factors contributing to the deterioration of insulation resistance on marine electrical machinery.
(b) Explain how insulation test reading are made and interpreted.
(c) Describe a suitable on board procedure for drying out an electric motor.

198) (a) Briefly describe the factors which contribute to the deterioration of insulation on marine electrical machinery and how these factors are taken into account in the design of the equipment or in its operation.
(b) Describe briefly how insulation test readings are taken and interpreted.

199) (a) Explain what effects accumulation of dirt may have on electrical insulation of machinery.
(b) State the possible consequences of allowing the ventilation ducts of machinery to become choked with dirt.
(c) State the precautions necessary when cleaning heavy deposits of dirt from the insulated winding of electric motors.

200) (a) List desirable properties of electrical cable insulation onboard ship,
(b) Explain why insulation of an idle machine may risk greater deterioration than a running machine.

201) (a) Briefly describe how the condition of electrical insulation may be measured.
(b) Explain how the amoient atmospheric conditions may influence the instrument readings.

Electrical Systems, Batteries, Etc
202) (a) State the essential electrical systems aboard ship which require the back up of an emergency battery bank.
(b) Explain how an emergency battery bank is maintained in a fully charged condition.
(c) Describe the routine maintenance procedures required for a bank of lead-acid batteries.
203) With reference to a bank of emergency lead-acid batteries :
(a) State the condition of the battery bank if the specific gravity of a number of cells in the bank is in the region of 1.11, with an ambient temperature of 160 C,
(b) describe a systematic procedure for checking the condition of the battery bank if it is divided into two sections for charging.
(c) describe the necessary routine maintenance.

204) (a) List the electrical systems aboard ship where continuity of supply from emergency sources if essential in the event of mains power failure.
(b) Briefly describe the major features of a typical emergency electrical supply system.
(c) Explain how an emergency a.c. generator can be arranged to start automatically in the event of mains power failure.

203) With reference to an emergency source of electrical power in cargo ships:
(a) Describe a typical power source.
(b) Give a typical list of essential services, which must be supplied simultaneously.
(c) Explain how the emergency installation can be periodically tested.

205) (a) State the form of protection provided for electrical equipment associated with a ship's steering gear.
(b) Explain the difference between short circuit and overcurrent protection of electrical equipment.
(c) Explain how the setting of an electrical overload protection device is determined.

206) (a) State why earth faults must be cleared an soon as possible.
(b) With the aid of a wiring diagram explain how earth faults.
(c) Briefly describe how an earth fault on a three phase insulated system is located.

207) (a) Explain why the risk of electric shock is greater with a.c. portable appliances than with fixed appliances.
Briefly describe how the risk of shock to personnel can be minimized on board ship by :
(b) design of the electrical system,
(c) care in operation of equipment.

208) (a) Briefly describe the general effect if a shore supply of 60 Hertz was connected to a ship system designed to work on 50 Hertz.
(b) State the effect on a motor designed to run on 50 Hertz supplied with a frequency of 45 Hertz.
(c) Explain why a stalled squirrel cage motor would burn out if the protective devices failed to operate quickly.

209) (a) State why incandescent lamps can be dimmed by simply regulating the applied voltage whereas this method cannot be used with gas discharge lamps.
(b) State under what circumstances the assumption that, a lamp maintains its value as long as it still functions, is wrong.
(c) State FOUR factors which influence the life of gas discharge lamps.

210) (a) Briefly describe how storage batteries may be charged from high voltage a.c supply.
(b) State two methods by which the condition of an alkaline storage battery may be checked.

211) Briefly explain the function of the following stating where it may be used on board ship :
(a) Rectifier,
(b) Thyristor,
(c) Transistor

212) (a) Explain the effect of connecting up a 60 Hz supply from ashore to a ship's normal 50 Hz system.
(b) State the checks that need to be made before a shore supply is connected up.
(c) Explain why it is necessary to earth the ship.

213) (a) Briefly describe the protection provided for electrical equipment associated with a ships steering gear.
(b) State the checks that need to be made before a shore supply is connected up.
(c) Explain why it is necessary to earth the ship.
214) (a) Briefly describe the protection provided for electrical equipment associated with a ships steering gear.
(b) Distinguish between short-circuit protection and over-current protection.
(c) Briefly describe how the setting of an electrical overload protection device can be checked.

215) With the aid of sketch explain the effect of:
(a) a single earth on a circuit.
(b) two earths on a circuit.
(c) Describe a test to ascertain earthing of a circuit on board ship where earth lamps are not in operation.
(d) State how an earth would be located once it is ascertained to exist in a particular circuit.

216) (a) Distinguish between 'Primary cell' and 'Secondary cell' and between 'acid cell' and 'alkaline cell'.
(b) Describe how a battery of alkaline cells may be tested for its usefulness after a lone storage and if found deficient how it can be remedied.

217) With reference to fuse protection for an a.c. induction motor :
(a) State the reason for this form of protection.
(b) State the factors that need to be considered when selecting the correct fuse rating.
(c) Briefly describe the procedure to follow if fuse replacement are continually blowing.

218) (a) Giving a set of typical readings, describe how the condition of a lead acid storage battery can be checked.
(b) State whether the ambient temperature is relevant while ascertaining the condition of the battery and if so how is it relevant.
(c) Briefly describe the care and routine maintenance that would be necessary with a bank of emergency lead-acid batteries.

219) (a) List the essential systems aboard ship which require the back up of an emergency battery bank.
(b) Describe how an emergency battery bank is maintained in a fully charged condition.
(c) Outline a routine maintenance procedure for a bank of lead-acid batteries

220) (a) Draw a complete circuit diagram for an emergency a.c. electrical supply system showing the connection to essential services and protection devices.
(b) Describe how the system comes into effect in case of a 'black out'.

221) (a) Briefly describe a typical emergency power source for cargo ships stating its location and method of periodic testing.
(b) Give a typical list of essential services which would normally be supplied by this emergency power source.

222) (a) Sketch a line diagram for earth detector lamps or a three phase insulated a.c. system.
(b) State how earth faults are indicated and interpreted,
(c) State why earths must be traced and rectified as soon as possible.

223) (a) Explain why earthing of the neutral wire in three phase a.c. systems requires an earthing resister,
(b) Briefly describe how the magnitude of such a resister is chosen.
(c) draw a simple line sketch shoeing such an earthing arrangements.

224) (a) State what is meant by flame proof equipment, with respect to hazardous atmospheres.
(b) Sketch and describe how the "mechanics" of flame extinction are achieved in a flame proof lamp fitting.
(c) Describe what precautions are taken when reassembling a flame proof
(i) lamp fitting
(ii) motor
after having been removed ashore for overhaul, and comment as to the inspection you would give to this equipment after having been repainted by ship's staff.

225) (a) Describe the possible effects of dirt accumulating in electrical machines.
(b) Describe suitable procedures for cleaning electrical machines, which are heavily contaminated with dirt deposits.
(c) Explain why re-varnishing of electrical machines is carried out and the necessary precautions to be observed.

226) (a) Explain the meaning of single phasing in a.c. machinery.
(b) State the dangers associated with single phasing and the protective devices normally fitted to counteract such dangers.

227) With the aid of circuit diagrams suggest with reasons which ONE or combination of the following faults in a three phase a.c. circuit will give rise to the following condition of the earth lamps:
Phase I,Slightly dull; Phase II,dark ; Phase III,half brilliance
Phase I Phase II Phase III
(a) heavy earth no earth light earth
(b) no earth dead earth light earth
(C) light earth heavy earth light/heavy earth
(d) light earth heavy earth light/heavy earth

228) (a) Given a set of typical readings, describe how the condition of a lead acid storage battery can be checked.
(b) State whether the ambient temperature is relevant while ascertaining the condition of the battery and if so how is it relevant.
(c) Briefly describe the care and routine maintenance that would be necessary with a bank of emergency lead-acid batteries.

229) (a) Distinguish between 'Primary cell' and 'Secondary cell' and between 'acid cell' and 'alkaline cell'.
(b) Give an example of a primary cell.
(c) Describe how a battery of alkaline cells may be tested for its usefulness after a long storage and if found deficient how it can be remedied.

230) (a) Explain why the risk of electric shock is grater with a.c. portable appliances than with fixed appliances.
(b) Briefly describe how the risk of shock to personnel can be minimised on board ship by :
(i) design of the electrical system, and
(ii) care in operation of equipment.

231) With reference to three phase induction motors :
(a) State the precautions necessary before maintenance work can be carried out.
(b) State the type of bearings normally fitted and give reasons for their choice.
(c) Explain why such a motor might run in the wrong direction and how the fault would be corrected.

232) (a) State the general effect of connecting a ship's electrical system based on a frequency of 50 Hertz with a shore supply of 60 Hertz.
(b) Describe the effect on an a.c. electric motor which is supplied with current at a frequency lower than that for which the motor was designed.
(c) Explain why a stalled squirrel cage motor would burn out if the protective devices failed to operate quickly.

233) With reference to three phase a.c. motors :
(a) State the limitations of direct on line starting.
(b) Describe a method of starting other than direct on line.
(c) Explain why the motor designed for delta connected windings must not be connected so that the motor runs star connected.

234) (a) Explain why dirt should not be allowed to accumulate on insulation surfaces between exposed live parts on electrical equipment.
(b) Describe the possible consequences of allowing ventilation ducts on electric motors to become choked with dirt.
(c) Describe the precautions necessary when cleaning heavy deposits of dirt from the insulated windings of electric motors.

235) If an electrical machine aboard ship becomes accidentally immersed in sea water :
(a) State why sea water can be particularly damaging to the machine and briefly describe any remedial action necessary prior to carrying out a drying process.
(b) Explain how the machine should be dried out and the precautions necessary to ensure that the drying process is satisfactory.
(c) Explain how it is determined that the drying process has been satisfactorily completed.

236) with reference to fuse protection for an a.c. squirrel cage motor :
(a) State the reason for this form of protection.
(b) State the factors to be considered when selecting the correct fuse rating.
(c) Describe the procedure to follow if fuse replacements are continually blowing.

237) (a) Describe briefly the function of slip rings in electrical machines.
(b) Mention the regular attention necessary to such components and possible dangers if maintenance is neglected.
(c) State the approximate pressures on slip ring brushes and describe briefly how slip rings may be cleaned.

238) (a) Explain why it is necessary to restrict current in starting an a.c. motor.
(b) Mention two such methods of starting and indicate the suitability of each for particular operation.
(c) State the maintenance necessary to keep starters in good working order.

239) (a) Explain the meaning of single phasing in a.c. machinery.
(b) State the dangers associated with single phasing and the protective devices normally fitted to counteract such dangers.

240) (a) State the precautions necessary before maintenance work can be carried out on an induction motor.
(b) state the maintenance that is normally required in such a motor.
(c) Explain how such a motor may run in the wrong direction on restart.

241) With reference to three phase induction motors explain how the following faults may occur and be remedied :
(a) 'burn out'
(b) overheating,
(c) running in wrong direction.

242) (a) Show a diagrammatic sketch of a self excited a.c. generator and explain its operation.
(b) State how two a.c. generators may be brought in parallel safely.

243) (a) Describe with a sketch how a motor may run on both a.c. and d.c.
(b) Mention limitations and uses of such a motor on board ship.

244) (a) State with reasons what type of a.c. motor can be started direct on line and why other types cannot.
(b) Describe a method of starting other than direct on line and justify its use on a particular type of a.c. motor.

245) (a) Give THREE applications of wound-rotor type of induction motor on board ship and justify the reasons for its use.
(b) Give FOUR applications of squirrel cage type of induction motor on board ship justifying the reasons for its use.
(c) Briefly describe the safety fittings provided to protect these motors.

246) (a) Describe the possible effects of dirt accumulating in electrical machines.
(b) Describe suitable procedures for cleaning electrical machines which are heavily contaminated with dirt deposits.
(c) Explain why re-varnishing of electrical machines is carried out and the necessary precautions to be observed.

247) (a) State the advantages of the induction motor over the synchronous motor.
(b) State whether there are any disadvantages.
(c) State TWO suitable applications of each type of motor on board ship justifying the reasons of suitability.

248) (a) State with reasons the instruments necessary for running of an a.c. generator and for its parallel operation.
(b) Explain the necessity for an instrument transformer and state what provisions are made to protect the instruments in the event of insulation breakdown between the primary and secondary circuits.

249) (a) Explain why a current surge may take place in a.c. electrical machinery.
(b) State TWO likely instances of current surge on board ship and the methods of minimizing it.

250) With reference to a a.c. electrical motors define the causes of and remedies for :
(a) overheating,
(b) vibration,
(c) magnetic noise.

251) With reference to the instrumentation required for a.c. generators :
(a) Explain the function of instrument transformers.
(b) Describe the protection necessary to safeguard personnel and instruments if there is a breakdown of insulation between the primary and secondary circuits of instrument transformers.
(c) State with brief reasons, the instruments necessary for parallel operation.

252) (a) Describe briefly the function of commentator rings in electrical machines.
(b) Mention the regular attention necessary to such components and possible dangers if maintenance is neglected.
(c) State the approximate pressures on slip rings brushes and describe briefly how commutator rings may be cleaned.

253) State how the following conditions affect the condition and performance of induction motors :
(a) worn bearings,
(b) dust laden atmosphere,
(c) overloading.

254) (a) Show a diagrammatic sketch of an a.c. generator and explain its operation.
(b) State how two a.c. generators may be brought into parallel operation safely.

255) With reference to three phase induction motors :
(a) define with reasons the type of bearings normally fitted,
(b) Compare the size of the air gap with that of other electrical motors, and
(c) State why such a motor might run in the wrong direction and how the fault would be corrected.


Switchboards
256) (a) State what is meant by a 'dead front' switchboard.
(b) Explain how access to switchgear in a dead front switchboard is made from the front.
(c) Describe the precautions necessary before commencing work on switchgear to which access has been made as indicated in (ii)
257) (a) State the necessary operations for paralleling an a.c. generator with live busbars.
(b) Explain the precautions taken when paralleling to avoid excessive current surge.
(c) With the aid of a sketch show how two synchronising lamps can be fitted in conjunction with a synchroscope. Indicate whether the lamps are arranged for 'lamps bright' or 'lamps dark' operation.

258) With reference to electrical equipment in areas aboard ships having potentially flammable atmospheres :
(a) explain the hazards involved,
(b) describe one method of rendering the equipment safe,
(c) explain the precautions necessary when maintenance work is carried out.

259) With reference to the instrucmentation required for a.c. generators
(a) Explain the function of instrument transformers.
(b) Describe the protection necessary to safeguard personnel and instruments if there is a breakdown of insulation between the primary and secondary circuits of instrument transformers.
(c) State, with brief reasons, the instruments necessary for parallel operation.

260) (a) State why earth faults on electric cables or equipment should be cleared at the earliest opportunity.
(b) Describe a systematic procedure for locating earth faults aboard ship.
(c) State, with reasons, the most common locations of earth faults aboard ship.

261) (a) State why "dead front" switchboards are required for a.c. systems having voltages to earth greater than 55 V.
(b) Explain how sections of an electrical system aboard ship can be isolated for maintenance work.
(c) Describe the procedure to replace a three phase induction motor with a spare.

262) With reference to cargo pumprooms on oil tankers :
(a) Describe the measures taken to prevent electrical faults on lamp fittings from igniting flammable atmospheres.
(b) Describe the arrangements made to allow lamp replacement or maintenance work to be safely carried out without extinguishing all lamps in the pumproom.
(c) State possible defects to lamp fittings and associated wiring which can render the installation unsafe.

263) With reference to electrical contractors :
(a) Explain how copper contactors are kept free of oxide formations.
(b) Explain why the contact pressure maintained by spring force is
important.
(c) Describe the functions of auxiliary contacts.

264) (a) Explain the necessity of keeping electrical contactors clean, and closed with a firm contact pressure.
(b) Describe briefly the functions of auxiliary contacts.
(c) State how copper contactors are kept free of oxide formations.

265) (a) Explain the meaning of a "dead front" switchboard as against a 'dead' switchboard.
(b) State TWO faults that may develop with copper contactors and how these may be remedied.
(c) State the function of auxiliary contacts.

266) (a) Sketch a circuit breaker as fitted in an a.c. system and explain its operation.
(b) State where and why such circuit breakers are fitted.
(c) Compare the operation of a circuit breaker with a fuse.
(i) Briefly explain how a synchroscope works.
(ii) State the use of a synchroscope on board ship.
(iii) Draw a simple line diagram to explain the use of a synchroscope.

267) (a) Briefly describe the procedure of paralleling an a.c. generator with live busbars explaining the reasons for the precautions.
(b) By a simple diagram show how tow lamps can be fitted in conjunction with a synchroscope for paralleling operation and indicate whether lampls are arranged for 'lamps bright' or 'lamps dark' operation.

268) (a) Explain why 'low voltage' protection is provided in a.c. systems.
(b) Briefly describe how this protection is effected.
269) (a) Differentiate between an 'open type' and a 'dead front' switch board.
(b) Briefly explain how access to switchgear in a dead front board is made.
(c) List precautions necessary before commencing work on any type of switchboard.


Stabilizers, rudders
270) (a) Sketch the activating gear for a stabilizer fin which folds into a hull aperture.
(b) Describe how it operates.
271) (a) Sketch in detail a bearing designed to transfer the full weight of rudder and stock to ship structure.
(b) Explain why the thrust faces are so contoured.
(c) Explain why a rudder may tend to lift and how this tendency is countered.

272) With reference to rudders explain how:
(a) badly worn pintles can led to rudder stock fracture,
(b) a watertight hollow rudder reduces a ship's deadweight,
(c) offsetting of palms from the axis of the rudder stock does not place an undesirable torque on the pintles.

273) With reference to rudders state :
(a) Why a breached hollow rudder can add to fuel costs,
(b) why excessive pintle clearance should not be tolerated,
(c) why palms are sometimes stepped and fitted bolts used in connecting upper and lower stocks.

274) (a) Sketch in diagrammatic form a stabilizer unit in which the fins retract athwartships into a recess in the hull.
(b) Describe how the extension/retraction sequence is carried out.
(c) Define how the action of fin stabilisers effects steering.

275) (a) Sketch in diagrammatic form a passive tank stabiliser system, labelling the principal components.
(b) Explain how the system illustrated in (a) functions in heavy weather.
(c) State how it is prevented from getting out the phase with ship motion and aggravating roll.

276) (a) Define the purpose of installing twin skeg rudders.
(b) Identify the problems associated with twin rudder installations.
(c) State why skeg or spade rudders are 'free hanging', whilst semi- balanced rudders carry pintles.

277) (a) Sketch in diagrammatic form a stabilizer unit in which the fins fold into a recess in the hull.
(b) Describe how the folding/unfolding sequence is carried out.
(c) Give one advantage and one disadvantage it possesses compared to the non-folding fin stabliser unit.

278) (a) Give reasons why it is essential that the watertight integrity of hollow rudders be maintained.
(b) State why rudder pintle clearance should not be allowed to become too coarse.
(c) State why fitted bolts are used in rudder stock couplings and why the nuts should be regularly checked for tightness.

279) (a) Sketch a rotary vane type steering gear, and itemise the advantages claimed for this type compared with the multiple ram type.
(b) Describe two operational factors which could adversely effect sealing arrangements of a rotary vane steering gear and state how you would try to limit or control theses factors.

280) With reference to ram steering gears :
(a) How are large wave forces on the rudder accommodated,
(b) Explain how the rudder is returned to its original position after being displaced by a large wave without any further action or signal form the bridge.
(h) Discuss the consequences of allowing rudder weardown to become excessive and state one effect that might show that this was happening.

281) (a) Give reasons why it is essential that the watertight integrity of hollow rudders be maintained.
(b) State why rudder pintle clearance should not be allowed to become too course.
(c) State why fitted bolts are used in rudder stock couplings and why the nuts should be regularly checked for tightness.


Propellors, thrusters, etc
282) (a) Sketch diagrammatically the blade actuating system of a Controllable pitch propeller, labeling the principal items
(b) Describe how the blades follow bridge control.
283) With reference to keyless propellers explain :
(a) Why keys and key ways have been eliminated,
(b) how angular slip is avoided.
(c) why mounting upon and removal from a propeller shaft requires a different technique than that employed for propellers with keys.

284) Explain with sketches how watertightness of an external seal for a propeller shaft is achieved :
(a) on passage,
(b) during an afloat survey of the propeller shaft in port.

285) Give reasons why each of the following conditions contributes to an increase in propeller slip:
(a) vessel in ballast condition.
(b) heavily fouled hull,
(c) damaged propeller blades.
(d) Explain why astern propeller slip is appreciably greater than ahead slip.

286) (a) Sketch in detail an external seal arrangement for a propeller shaft.
(b) give two reasons for seal failure.
(c) state how the incidence of seal failure can be reduced.

287) (a) Sketch in diagrammatic form the blade actuating mechanism of controllable pitch propellers.
(b) Give a simple description of its operation in changing the pitch from the full ahead to the full astern mode.
(c) State how blade pitch can be altered upon failure of bridge control.

288) With reference to solid propellers state:
(a) how badly damaged blade tips are restored,
(b) why propellers need balancing form time to time,
(c) why intense concentrated heat should not be applied to bosses.

289) With reference to transverse thrust units define :
(a) the primary purpose for their installation,
(b) with reasons where they are usually located,
(c) how reversal of thrust is accomplished,
(d) how thrust can in some cases be directed.

290) (a) State why new or replacement solid propellers should never be permanently mounted on propeller shafts for the first time until compatibility of the tapers, and fit between the keys and keyways, has been verified as satisfactory.
(b) Explain how compatibility of tapers I ensured.
(c) Define the nature of the required fit between keys and keyways, in (i)

291) (a) Give reasons why the Pilgrim nut has greatly facilitated the mounting and unseating of solid propellers on and from shaft tapers.
(b) Sketch a propeller nut of the Pilgrim pattern.
(c) Give a brief explanation of how the Pilgrim nut is used in propeller withdrawal.

292) With reference to controllable pitch propellers :
(a) explain why the blade attitude assumed upon control failure is considered safe,
(b) Describe how the 'fail safe' feature operates,
(c) state how the ship can be maneuvered when the bridge control is out of action.

293) With reference to controllable pitch propellers :
(a) Sketch in diagrammatic form the arrangement whereby the command signal from the bridge is conveyed to the blade actuating mechanism housed in the rotating propeller shaft,
(b) State how the blade actuating mechanism is protected against ingress of sea water,
(c) state how and why upon failure of pitch control the blades assume a particular pitch angle.

294) With reference to solid propellers state why :
(a) great care must be taken when mounting by 'hydraulic push-up' or 'hyfraulic floating' that the propeller does not go beyond the witness marks on the shaft taper,
(b) in spite of correctly mounting the propeller the nut must be properly tightened and locked,
(c) under normal circumstances the boss should be well 'bedded in' to the shaft taper.

295) (a) Sketch in diagrammatic form any type of transverse thrust unit including the power unit, labelling the principal components.
(b) Explain how this unit operates.
(c) Give reasons for its installation in both lone-haul container carriers and short sea trade 'ro ro' ferries.

296) (a) Specify with reasons the conditions to be met when fitting solid propellers to propeller shafts for the first time.
(b) Give reasons why intense, concentrated, heating of propeller bosses should not be employed to facilitate unseating of solid propelellers from their shafts.
(c) State why propeller nuts need to be locked after tightening.

297) (a) Identify the two parts of ships propulsion machinery which usually cause vibration.
(b) State how vibration can adversely effect :-
(i) Electric motors
(ii) Small bare oil pipes
(iii) Holding down arrangements
(iv) Switch boards
(v) Damping arrangements on instruments.< > (c) A pressure gauge needle vibrates unduly, discuss means that can be taken to reduce this.

298) (a) With reference to an oil lubricated sterntube explain the need for a hydraulic balance.
(b) Why does bearing wear down effect this balance.
(c) Itemise the factors which adversely effect seal life.
(d) If the seals fail how can oil loss be restricted.

299) (a) Give reasons why the Pilgrim nut has greatly facilitated the mounting and unseating of solid propellers on and from shaft tapers.
(b) Sketch a propeller nut of the Pilgrim pattern.
(c) Give a brief explanation of how the Pilgrim nut is used in propeller withdrawal.

300) The tightness of a nut and bolt system might be critical, describe THREE ways in which this tightness may be established with much more certainty than flogging up the nut to old marks.

Corrosion, fouling
301) (a) Identify the most likely areas of corrosion in the ini of the dry cargo vessel.
(b) Describe how corrosion in these areas can be inhibited.
(c) State how plate thickness and wastage is determined.
302) Define with reasons the main purpose of each of the following practices :
(a) Use of neoprene washers in the connection between aluminium superstructures and ships main structure,
(b) attachment of anodic blocks to the underwater surface of a hull,
(c) external shotblasting and and priming of hull plating.

303) (a) State how larger ship sides valves can be kept from fouling.
(b) State what regular attention is advisable to ensure their easy operation at all times.
(c) Give two advantages and two disadvantages of sluice valves compared with mitre seat valves for use as sea connections.

303) (a) Identify the localities, internally and externally on hull plating, most prone to corrosive action.
(b) Give reasons for this aggressive attack in each of the instances cited in (i)
(c) State how such action can be inhibited in any one of the instances cited in (i)

304) Give a reason for corrosion in each of the following instances :
(a) connection between aluminium superstructure and steel deck,
(b) in crude oil cargo tanks,
(c) Explain how in each case corrosion can be inhibited.

305) (a) Identify the main causes of corrosion in a ship's internal structure.
(b) Define the measures taken to minimise this action.
(c) State what parts of the internal structure are most liable to corrosion.

306) (a) state how freshwater tanks are prepared for inspection.
(b) State how the surface of the steelwork is treated prior to refilling.
(c) Give reasons for the manner of treatment employed in (ii)
(d) Give reasons why fresh water from such tanks is quite suitable for human consumption and yet fresh water produced by evaporation of sea water is not necessarily suitable for such purposes.

307) (a) Explain how steel work in cargo oil tanks is exposed to active wastage.
(b) Identify with reasons those areas most likely to be affected by such action.
(c) Define the various methods employed to minimise corrosion in oil tanks.

308) (a) Identify three different corrosion problems encountered in ship structure.
(b) Define the origins and significance of each
(c) State what precautions are taken to reduce their effects.

309) Describe the reason for corrosion :
(a) at aluminium and steel connections,
(b) in the proximity of the propeller, and
(c) in oil fuel cargo tanks.
Explain in each case how the corrosion can be prevented.

Systems, Safety
310) State with reasons why the following practices should be encouraged:
(a) tank sounding cocks kept free to operate easily,
(b) tank air pipes kept free from heavy wastage at weather deck level
(c) extended spindles to bilge valves kept free to operate easily, trip wires to fuel tank suction valves kept free to operate easily,
(d) trip wires to fuel tank suction valves kept free from fretting,
(e) wire gauze, as fitted over the mouth of some tank vents, kept unpainted.
311) (a) Draw a line diagram of a bilge suction distribution s dry cargo vessel, showing the disposition of the bra in the various compartments and of the available pump
(b) Give three common reasons for failure to empty bilge
(c) State how each of the faults in (ii) are traced and

312) with reference to the filling of fuel ballast tanks with water ballast explain :
(a) how overpresure in the tanks can occur and what would be the consequences,
(b) the undesirability of slack tanks,
(c) State how each of the faults in (ii) are traced and

313) With reference to ballast systems in dry cargo vessels state with reasons where :
(a) main and branch lines run in relation to the ship's side and tanks respectively,
(b) air and sounding pipes are located in the tanks.
314) Define the main purpose of the following tank and pumping system details :
(a) weighted cocks on tank sounding pipes.
(b) remote operating gear for bilge valves,
(c) ventilation pipes for double bottom tanks,
(d) explain why copper gauze is sometimes fitted to tank ventilation pipes.

315) Sketch and describe a self-contained breathing apparatus. Give two advantages and two disadvantages of this equipment compared to the smoke helmet. State the signal system used when wearing breathing apparatus.

316) (a) Explain how a set of chain lifting gear is maintained in good condition.
(b) Describe how a cumbersome machinery component is lifted from the lower engine room level to the boat deck with the aid of only ship's staff and equipment.
(c) State what precautions requires observance during the operation to ensure maximum safety.

317) (a) Identify the ways, apart from a collision, in which large quantities of sea water can quickly enter the engine room, and
(b) Describe in each case how you would try to either stop or limit this trouble.
(c) What is the likely consequential damage that is likely to occur if the sea water rose to the engine room plates before being stopped.

318) As the second engineer what advice with regard to personal safety would you give to a young engineer about the following :-
(a) Working under the engine room plates
(b) Dismantling a centrifugal pump casing
(c) Renewing a boiler water gauge glass while the boiler was steaming.
(d) Working with portable electric hand tools,
(e) Opening up a steam valve after the main steam stop valve on the boiler has been closed.

319) (a) State what problems arise from the alternate use of double bottom tanks for the carriage of oil fuel and water boiler.
(b) State why such arrangements are sometimes necessary.
(c) Describe how the mixing of fuel and ballast in prevented.
(d) State how legislation on oil pollution is observed.

320) Define with reasons the main purpose of each of the following prc (a) bilge m outside the machinery spaces confined within a central sixty per cent of the ship's breadth.
(b) discharges led overboard from normally inaccessible spaces below freboard decks kept locked shut whilst or voyage.

321) (a) Define the purpose of air pipes associated with double bottom fuel tanks.
State what provisions are made with such air pipes with respect to :
(b) heavy weather,
(c) fire,
(d) bunkering.

322) State with reasons why the following should be encouraged :
(a) tank sounding cocks kept free to operate easily,
(b) tank air pipes kept free form heavy wastage at weather deck level.
(c) extended spindles to bilge valves kept free to operate easily,
(d) trip wires to fuel tank suction valyes kept free from fretting,
(e) wire gauze, as fitted over the mouth of some tank vents, kept unpainted.

323) Enumerate the precautions necessary before entering tanks in which fuel oil has been carried,
List the advantages and disadvantages of using the following when inspecting empty oil fuel tanks :
(a) equipment fitted with a battery or accumulator, and
(b) equipment operated from the ship's electrical system.

324) (a) Before entry into an enclosed space which has previously contained oil it is essential that the atmosphere be tested, identify the tests.
(b) How are the instruments checked to ensure that they are operating normally prior to checking the enclosed space.
(c) With the aid of a sketch describe one of the instruments and state the principle of its operation.

325) State why oxygen deficiencies may occur in certain spaces in ships.
Describe the precautions taken before entry to any recently opened space.
State how and why a bottle is checked before use and explain how the warning is given that a bottle is nearly exhausted.

326) (a) What is the principle behind the fitting of an inert gas system on a tanker.
(b) Why has corrosion been one of the major problems with inert gas and what can be done to limit this problem.
(c) What part in the system does PRESSURE/ VACUUM valves play.
(d) Itemise the major controls fitted to an inert gas system.

327) (a) Describe with the aid of a simple block sketch an inert gas system for a tanker.
(b) Explain the reason why a number of safety features are incorporated in the system.
(c) Discuss briefly the material needs in scrubbing tower design.


General Ship Construction, drydock
328) Define the circumstances necessitating, and the purpose of, the following tests sometimes carried out on ship's hulls in dry dock:
(i) hose,
(ii) hammer,
(iii) drill,
(iv) ultra sonic.
State with reasons which part of the external plating of ships' hulls needs the closest attention.
329) Define with reasons the purpose of the following ship construction details:
(j) bulbous bow,
(ii) bow flare,
(iii) bilge keels,
(iv) sheer.

330) (a) Define the purpose of cofferdams.
State where cofferdams are most likely to be found in :
(b) dry cargo vessels,
(c) oil tankers.
(d) Identify with reasons the precautions to be observed before and during entry to cofferdams.

331) Give reasoned explanations for the following ship construction details:
(a) weather deck entrances to compartments below freeboard deck provided with sills and water tight doors,
(b) large capacity scuppers with non-return valves located in the enclosed vehicular deck in ro/ro vessels,
(c) watertight doors in subdivision a bulkheads are strictly limited in size and number.

332) Define briefly the construction details peculiar to each of the following types of closure that enables their primary function to be fully realized :
(a) water tight doors,
(b) fire proof doors,
(c) gas tight doors.
(d) State why (i) can perform the function of (ii) and (iii), whereas (ii) and (iii) are restricted solely to their primary function.

333) Describe with sketches the provisions made for draining and / or pumping the following spaces :
(a) 'tween deck spaces,
(b) fore peak tanks,
(c) chain lockers

334) (a) Give reasons why scuppers are generally located in close proximity to superstructure, deckhouses and other weather deck erections, whereas freeing ports are generally located in open areas of the weather deck.
(b) Explain why it is essential that scuppers and freeing ports should function satisfactorily at all times,
(c) State why oil tankers in particular have ship side guard rails abreast cargo tanks for reasons other than personnel safety.

335) (a) Sketch the following types of rolled steel sections in a representative role to stiffen plating :
bulb angle, angle bar, offset-bulb plate, flat bar.
(b) State where in ship's structure these rolled sections are commonly used.
(c) Define with sketches other means used to stiffen large areas of plating.

336) Give a reasoned explanation why:
(a) watertight doors are generally located in machinery spaces, and fire doors in accommodation spaces,
(b) all fire and watertight doors can be closed and opened from either side,
(c) alarms are normally associated with watertight doors only, (d) compared to fire doors, watertight doors are cumbersome in construction and slow in action.

337) (a) Identify four materials used for insulating refrigerated spaces.
(b) Give four qualities which such an insulating material must possess.
(c) Describe with sketches how a refrigerated cold store in insulated.

338) (a) Select and sketch in diagrammatic form a water tight door primarily operated by either electrical or hydraulic power, showing in detail the closing arrangements.
(b) Identify with reasons the various stations from which the door can be closed.
(c) Identify two safety devices incorporated in the actuating system of (i)

339) Make a sketch of a watertight door giving details of the fastening arrangements to show how edge watertightness is maintained.
Describe the procedure adopted for testing two or the following for watertightness :
(a) a watertight door,
(b) a deep tank bulkhead, and
(c) a hold-bulkhead in a dry cargo ship.

340) Describe briefly how freshwater double bottom tanks are cleaned for inspection and how the surface of the steel work should be treated prior to filling.
As Engineer Officer responsible for opening the tank, directing cleaners, inspecting, closing and refilling the tank, state the precautions that should be observed.

341) Suggest with reasons weather 'build up' by welding, patching, cropping or plate replacement is best suited to the following structural defects :
(a) severe pitting at one spot on deck stringer,
(b) external wastage of side plating below scuppers,
(c) extensive wastage of side plating along waterline.

342) (a) Explain why pillars are fitted in ships.
(b) sketch a pillar, showing details of its head and heel attachment.
(c) Discuss whether compressive or tensile stress is the more important stress to which pillars are subjected.

342) Explain how temporary repairs can be made to the following with the equipment normally available at sea :
(a) badly corroded hatch coaming,
(b) fuel oil double bottom tank air pipe broken off at weather deck level.
(c) buckled watertight door frame, and
(d) crack in bulwork plating adjacent to accommodation.

343) (a) Your ship has entered dry dock and it has been decided to remove the tail shaft. Itemize the various stages of this work.
(b) What defects in the tail shaft would you particularly look for.

344) (a) Your ship is in drydock and you have been asked to inspect the anchor chain and its fittings, describe how you would carryout this work.
(b) How would you judge whether or not a shackle should be dismantled for a more thorough inspection.
(c) Make a sketch showing how the anchor chain can be held to prevent undue stress being put on the windlass.

345) (a) Itemize the preparations you would make on a ship about to enter drydock and comment abut the troubles or damage that might occur if the ship was drydocked unprepared.
(b) After the water has been pumped out of the drydock detail the examination you would make on the propeller and rudder.
(c) List any dimensions you would take when doing (b).

346) Your ship has run firmly aground and the main engine has been stopped, describe the steps you would take to start to limit the damage the engine space as much as possible.

347) Describe suitable arrangements for each of the following :
(a) penetration of watertight bulkheads by :
(i) rotating shafting
(ii) ballast pipes, and
(iii) electric cables.
(b) ventilating truck passing a fireproof bulkhead.
Explain how a fire is prevented from spreading along the trunking.


Compressors
348) (a) The performance of an electrically driven reciprocating type of air compressor has, over a period of time, fallen off. Give FIVE reasons why this could have happened, and state why each fault influences performance.
(b) Compressors are often fitted with automatic stop and start systems, describe how this system permits the electric motor to reach full speed before the compressor is loaded.
349) With reference to an air compressor :
(a) What is may be the first sign of loss of efficiency.
(b) What factors influence efficiency.
(c) If due to some reason or another the quantity of cooling is restricted what will be the effects.


General
350) Describe the locking devices used in the following :
(a) safety valve seat
(b) pump impeller
(c) rope guard on main propeller
(d) holding down botls of heavy machinery
Explain how you would check the effectiveness of (a).
351) (a) Sketch the drive arrangements for an electrically powered windlass and explain how the power can be diverted to one or other of the cable holders.
(b) How is the motor protected against overload.

352) (a) Give 3 reasons why 'blackouts' occur in engine rooms.
(b) Describe in some detail (after stating what type of ship you are dealing with) what needs to be done after a 'blackout' occurs to rectify the situation. Your remarks should be in reasonable order of priority.

353) (a) List the safety devices you would expect to find on a package boiler.
(b) Explain the procedure for testing all the safety devices when the boiler is started.

354) (a) Sketch how a safety valve seat is held in position.
(b) In detail, describe how a boiler safety valve is set after it has been dismantled for inspection.


W T DOORS
355) (a) Describe with the aid of a sketch how a hydraulically operated water tight door works.
(b) Explain the safety features normally fitted.
356) Explain the safety features normally fitted.
(a) Select and sketch in diagrammatic form a watertight door primarily operated by either electrical or hydraulic power, showing in detail the closing arrangements.
(b) Identify with reasons the various stations from which the door can be closed.
(c) Identify two safety devices incorporated in the actuating system.