The stern light is coloured white. A sternlight is a white light placed as closely as practical at the stern shining constantly, affixed in a manner so that the light will shine out at 135 degrees from the back of the boat and affixed to show the light from aft on each side of a pleasure craft.
The arc of the lights and color allows you to determine the direction a vessel is moving. How good are your lights? You should test them to see how visible you might be at night. Whether on a trailer or at the marina, switch on your lights and see how well they can be seen. Walk away from the boat or row away, if you are at anchor or at a mooring, and see how visible the lights are as you move further away. How easy are they to see against the background of lights on shore?
To learn more about the navigation lights that should be on a boat while navigating at night or in poor visibility, click here.