Tricolor light

On sailboats, it is permitted to display a single three-color light fixture at the top of the mast in lieu of the normally required sidelights and sternlight.

This fixture must shine red over an arc of 112.5 degrees from directly forward to port (replacing the port sidelight). The fixture must shine green over an arc of 112.5 from directly forward to starboard (replacing the starboard sidelight). And it must shine white to aft, over an arc of 225 degrees (replacing the sternlight).

The advantage of this light is that a single bulb can be used for all the required navigation lights when sailing at night. This decreases the amount of power needed from the ship's batteries. Another advantage is that the light is higher above the water and potentially more visible from a long distance.