Boat navigation lighting is not only there to protect the passengers on a boat, but they are also required by law if you plan on taking the boat out on the water in the evening. Navigation lights allow other boaters to understand the position and direction of your boat when it's dark outside. According to the United States Coast Guard, the size (length) of the boat determines what type of navigation lights that should be use.
If the boat is smaller that 13 meters (39.37 feet), the boat must have a red, green and all-around lights. These three lights will be found on the bow (2 lights) and aft (1 light) of the boat. A bi-colored boating navigation light is for the bow and the all-around navigation light will be on the back or center of the boat body. The bi-colored light will be at a 225 degree spread and the all-around light will be a 360 degree spread light.
If the boat is about 13 meters (39.79), the boat must have red and green lights on the side of the boat, a masthead light and a stern light. The red and green lights will be on the side of the boat with 112.5 degree spread. The aft side of the boat will have a white 225 degree masthead light and white 135 degree stern light.
It is paramount to follow these requirements for the safety they provide and to prevent problems.