Operational guidance for ships navigational light circuit

Use of navigational light circuits

The supply to the navigation lights circuit must be maintained under all circumstances and special provisions are therefore made. To avoid any possibility of accidental open circuits the distribution board for the navigation lights supplies no other circuit. A changeover switch provides an alternative source of supply should the main supply fail. If the navigation lights fail, a visual or audible indication must be given.

A navigation lights circuit is shown in Figure. Two sources of supply are available from the changeover switch. A double pole switch connects the supply to each light circuit, with a fuse in each line, A relay in the circuit will operate the buzzer if an open circuit occurs, since the relay will de-energise and the trip bar will complete the buzzer circuit. A resistance in series with the indicating lamp will ensure the navigation lights operate even if the indicating lamp fails. A main supply failure will result in all the indicating lamps extinguishing but the buzzer will not sound. The changeover switch will then have to be moved to the alternative supply.



Fig: Navigational light circuit