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Nighttime Navigation

Lights are required from sunset to sunrise. Always be on the lookout for the lights of other vessels when boating at night. Several types of lights serve as navigational aids at night.

There are four common navigation lights.

  • Sidelights: These red and green lights are called sidelights (or combination lights) because they are visible to another vessel approaching from the side or head-on. The red light indicates a vessel's port (left) side; the green indicates a vessel's starboard (right) side.
  • Sternlight: This white light is seen only from behind or nearly behind the vessel.
  • Masthead Light: This white light shines forward and to both sides, is located on the mast of a sailboat and is required on all motorboats. A masthead light must be displayed by all vessels when under engine power at night. The absence of this light indicates a sailboat under sail.
  • All-Round White Light On power-driven vessels less than 39.4 feet in length, this light may be used to combine a masthead light and sternlight into a single white light that can be seen by other vessels from any direction. When sidelights are extinguished, this light serves as an anchor light.
Sailboat showing sidelights, masthead light, and sternlight

Navigation lights on a sailboat under power

Powerboat showing all-round white light and red and green sidelights

Powerboat showing all-round white light and red and green sidelights

Encountering Vessels at Night

When you see only a white light, you are overtaking another vessel. It is the stand-on vessel whether it is underway or anchored. You may go around it on either side.

Navigation rule if you see only a white light

Encountering only a white light

When you see a green and a white light, you are the stand-on vessel. However, remain alert in case the other vessel operator does not see you or does not know the navigation rules.

Navigation rule if you see a white and a green light

Encountering a green and a white light

When you see a red and a white light, you must give way to the other vessel! Slow down and allow the vessel to pass, or you may turn to the right and pass behind the other vessel.

Navigation rule if you see a red light and a white light

Encountering a red and a white light

Encountering a Sailboat at Night

When you see only a red light or only a green light, you may be approaching a sailboat under sail and you must give way. The sailboat under sail is always the stand-on vessel!

Navigation rule if you see only a red light and a green light

Encountering only a red light

Navigation rule if you see only a green light

Encountering only a green light

Encountering a Non-Motorized Vessel at Night

When you see a white light from a lantern or flashlight, you may be approaching a canoe, kayak, or other similar vessel. At night, a non-motorized vessel less than 23.0 feet long must have either a 360-degree white light or a flare-up light to signal its location to all passing vessels.

Fig. 3: Sailboat and rowboat operators at night with flashlight

Required navigation lights on unpowered vessels less than 23 feet long