All boats need their running lights on between sunset and sunrise. Lights also need to be on during periods of restricted visibility.
A sailboat operating under power or under power and sail must display the proper lights for a power boat. Check lights to ensure that they are always working.
This section describes the inland and international requirements for boats less than 65 feet 7 inches. Often, the lights prescribed for a particular boat are the same under both rules. Any exceptions are noted.
Power-Driven Boats
On inland and international waters, a power-driven boat will show navigation lights, in graphic number one (1). Vessels less than 39 feet-4 inches will show the lights in figure 1 or 2 above. In international waters, motorboats less than 23 feet in length, where the greatest speed cannot exceed 7 knots shall exhibit an all-around white light or have ready at hand an electric torch or lighted lantern showing a white light shown in enough time to prevent a collision.
Sailboats and Manually Propelled Boats (Paddlecraft)
NOTE: A sailboat under motor-power and sail is considered a power-driven boat.
Sailboats under sail alone must exhibit navigation lights shone in graphic three below. Graphics 4 and 5 may also be used for boats under 23 feet in length.
Sailboats of less than 23 feet in length, shall exhibit an all-round white light, or have ready at hand an electric torch or lighted lantern showing a white light which shall be exhibited in sufficient time to prevent a collision. (See figure 6c above).
A manually propelled boat less than 23 feet may:
a) display those lights prescribed for sailboats or,
b) have ready at hand a flashlight or lighted lantern showing a white light to display in sufficient time to prevent a collision (see Figures 3 and 6 above).
Anchor Lights
Motorboats and sailboats at anchor must display anchor lights. An anchor light is an all-round white light visible for 2 miles and aimed forward where it is best seen. But vessels less than 23 feet are not required to display anchor lights unless anchored in or near a narrow channel, fairway, anchorage, or where other vessels navigate. Also, anchor lights are not required on vessels less than 65 feet-7 inches, anchored by a special anchorage area designated by the Secretary of Transportation.
Day Shape 
Vessels under sail and being propelled by a motor must display a conical day shape, apex down, for the best visibility (see graphic 7).
Automotive Equipment
Automotive equipment meant is not safe in gasoline-powered boats such as:
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starter motors,
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alternators/generators, and
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air cleaners
These electrical devices are not “ignition protected" and may generate sparks that can cause fires and explosions on inboard engines.