The number, position, location, shapes, color specifications, the intensity of light, visible range and sector of visibility of Navigational lights aboard ships are prescribed by the International Maritime Organization (IMO) in their “International Regulations for Preventing Collisions at Sea, 1972”
Navigation lights requirement
- Five specially designed navigation running lights referred to as Foremast, Mainmast (or Aftmast), Port, Starboard, and Stern.
- Two anchor lights, fitted forward and aft.
- The Sidelights are RED for PORT and GREEN for STARBOARD while the other lights are white.
- The typical power rating of 65 W but 60 W and 40 W ratings are also permitted in some cases.
- Two lamps and lamp holders within a special dual fitting.
- Each light is separately supplied, switched, fused and monitored from a Navigation lights Panel in the wheelhouse.
- The electric power is provided usually
at 220 V a.c. with the main supply fed from the essential services section of the main switchboard and an alternative standby power supply is fed from the emergency switchboard.
- A changeover switch on the Navigation lights Panel selects the main or standby power supply.
- The Navigation lights Panel has indicator lamps and an audible alarm to warn of any lamp or lamp-circuit failure.
- Each lamp circuit has an alarm relay which monitors the lamp current. The relay may be electromagnetic or electronic. Various signal lights with red green, white and blue colors are arranged on the signal mast.
- These lights are switched to give particular combinations to signal states relating to various international and national regulations. Pilotage requirements, health, dangerous cargo conditions, etc., are signaled with these lights.
- White Morse Code, Flashing lights may also be fitted on the signal mast.
- The NUC (Not under Command) state is two all-round red lights vertically mounted at least 2 m apart. Such important lights are fed from the 24V d.c. emergency supply.
Light type Vessel 50m (164 feet) or more in length Vessel between 12-50m (39-164 feet) in length Vessels less than 12m (39 feet) in length Masthead 6 miles 5 miles 2 miles Sidelight 3 miles 2 miles 1 miles Sternlight 3 miles 2 miles 2 miles
- Sidelights are red (port) and green
(starboard) and shine from dead ahead to 112.5° aft on either side.
- Stern lights are white and shine aft and 67.5° forward on each side. (Thus, the sidelights and stern light create a full circle of light.)
- All-round lights are white and shine through 360°.
- Masthead lights are white and shine from 112.5° on the port side through dead ahead to 112.5° on the starboard side. They must be above the sidelights.
- The construction of lights and shapes and the installation of the light on board the vessel shall be to the satisfaction of the appropriate authority of the state whose flag the vessel is entitled to fly.
Safeties during bulb changing on the Mainmast.
- Electrical work permit & Working Aloft permit should be made.
- Risk Assessment and Toolbox meeting should be done.
- The concerned circuit should be properly isolated.
- Whether should be calm.
- Should don proper PPE (personal protective equipment) including safety harness.
- Standby person.
- Radar and Air horn should be off.
- Put lock-out & Tag, Inform OOW (Officer on watch)
- Put notice “men at work”.