All boats operating between sunset and sunrise and during periods of restricted visibility are required to display the appropriate lights. Boats are considered underway and must show all the appropriate lights unless they are anchored, moored or aground. Anchored vessels must show the appropriate anchor lights. For more information on lighting see Inland Navigation Rules.
Boats built before December 25, 1981, and less than 20 meters (65 ft. 6 in.) shall exhibit navigation lights as displayed in either figure 1, 2 or 3.
Boats built after December 25, 1981, and less than 12 meters (39 ft. 4 in.)in length may use figure 1, 2 or 3.
Boats built after December 25, 1981, 12 meters (39 ft. 4 in.) or more in length but less than 20 meters (65 ft. 6 in.) must use figure 1 or 2.
If the lighting display in figure 1 is used, the aft masthead light must be higher than the forward one; if figure 2 is selected, a vessel less than 12 meters (39 ft. 4 in.) must have the masthead light 1 meter (3 ft. 3 in.) higher than the colored lights. If the vessel is using figure 2 and is 12 meters (39 ft. 4 in.) or more in length but less than 20 meters (65 ft. 6 in.) then the masthead light must be 2.5 meters (8 ft. 2 in.) higher than the gunwale.
A sailing vessel, under sail alone, shall exhibit the lights shown on figure 4, 5 or 6. A vessel under oars or a sailing vessel of less than 7 meters (22 ft. 10 in.) shall, if practicable, exhibit the lights prescribed in figure 4, 5 or 6. However, if she does not, she must have ready at hand an electric light or lighted lantern showing a white light as seen in figure 7 which must be exhibited in sufficient time to prevent collisions.
During daylight operation, vessels 12 meters (39 ft. 4 in.) and over using sail and machinery must display the shape of a black cone pointing down.
An anchor light is an all-round white light, visible for 2 miles, which is exhibited in the forepart of the vessel or where it can best be seen.
Power driven and sailing vessels less than 7 meters (23 feet) must display an anchor light when anchored in or near a narrow channel, fairway or anchorage where other vessels normally navigate.
Power driven and sailing vessels 7-20 meters (23 to 65.6 feet) are required to show an anchor light except when in a special anchorage area designated by the Secretary of Transportation or other authority.
A sailing vessel under machinery power and sails is considered a power-driven vessel.