A boat's lights are far more than decoration. They tell a seasoned sailor where the boat is, how big it is and which way it's moving. The colored lights also tell you what boats to avoid and even how to stay out of their way.
The colored lights--red, green, blue, yellow and white--are navigation and special-purpose lights. They provide an observer with information on the type and size of the vessel sighted, its activities and size to help prevent collisions between vessels.
Most navigation lights are "steady," that is, they don't flash. Flashing lights--yellow and blue--are special-purpose lights marking submarines, hovercraft, police boats and public service boats. A triangle of green lights is a minesweeper at work.
A steady red light marks the port (left) side of a boat; a steady green light marks the starboard (right). White lights are masthead lights or stern lights on the back of the boat. They make the boat visible at night. A steady yellow light marks the stern (back) of a tug pushing barges.
The position of the lights on a boat has significance. Large ships have white lights on two masts. The forward mast light is the lower of the two white lights, making it possible to tell which way a ship is moving.
The size, type, color and visibility of a ship's colored lights is dictated by the U.S. Coast Guard Navigation Rules. The Navigation Rules consist of two sets of regulations, one for international waters and one for inland waters.
- Image by Flickr.com, courtesy of Stephen Gore