Specific lighting configurations are required for boats operating between sunset and sunrise or in times of restricted visibility. It's your responsibility to make sure your boat shows the proper lights depending on its size and the waters on which you are operating.
The U.S. Coast Guard Navigation Rules, International-Inland encompasses lighting requirements for every description of watercraft. The information provided here is intended for power-driven boats and sailboats less than 20 meters (65.62 feet) long. The various options are illustrated.
Power-driven vessels of less than 20 meters (65.62 feet)
Power-driven vessels of less than 12 meters (39 feet 4 inches)
Power-driven vessels of less than 7 meters (23 feet)
whose maximum speed cannot exceed 7 knots may exhibit an all-around white light (360 degrees) and, if practicable, sidelights instead of the lights prescribed above, in international waters only.
Sailing vessels less than 7 meters may carry an electric torch or lighted lantern showing a white light to be displayed in sufficient time to prevent collision. If practicable, the lights prescribed for sailing vessels less than 20 meters should be displayed.
Vessels under oars (kayaks & canoes)
A canoe or kayak may display the lights prescribed for sailing vessels, but if not, must have ready at hand an electric torch or lighted lantern (flashlight) showing a white light to be displayed in sufficient time to prevent collision.
Power-driven vessels and sailing vessels at anchor must display anchor lights. An anchor light for a vessel less than 50 meters in length is an all-around white light visible for 2 miles and exhibited where it can best be seen.
Vessels less than 7 meters are not required to display anchor lights or day shapes unless anchored in or near a narrow channel, fairway or anchorage, or where other vessels normally navigate. Anchor lights are not required on vessels less than 20 meters, anchored in special anchorages in inland waters designated by the Secretary of Transportation.
The Navigation Rules require vessels restricted in their ability to maneuver to display appropriate day shapes or lights. To meet this requirement, recreational vessels engaged in diving activities may exhibit a rigid replica of the international code flag "A" not less than one meter in height or at night display the navigation lights as shown below (red/white/red).
This requirement does not affect the use of a red and white diver flag, which may be required by state or local law to mark a diver's location. The "A" flag (blue and white, shown above) is a navigation signal indicating the vessel's restricted maneuverability and does not pertain to the diver.
Navigation lights should be checked prior to departing the dock, and you should always carry spare bulbs. The USCG doesn’t care if they were working when you left, only that they are working when required.
Law enforcement vessel
A flashing blue light indicates a law enforcement vessel. Do not impede its operation.
If you see yellow lights or a flashing yellow light, stay away, it is a towing vessel with an object in tow.