Boating Basics: On the Water
Nighttime Navigation

Includes: Nighttime Navigation and Encountering Vessels at Night

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.

Types of Nighttime Navigational Lights

Illustrations

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: A white light seen from behind the vessel.

Masthead Light: A white light, which shines forward and to both sides, located on the mast of a sailboat and 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 able to 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 Powerboat showing all-round white light and red and green sidelights

Encountering Vessels at Night

Encountering Vessels at Night - What the Lights Mean	Illustrations of Lights
A green and 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.	Movie: See the action!
Only a white light: When you see only a white light, you are overtaking another vessel or it is anchored. It is the stand-on vessel whether it is underway or anchored. You may go around it on either side.	Movie: See the action!
A red 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.	Movie: See the action!
A red, a green and and a white light: When you see a red, a green, and a white light, you are approaching another power-driven vessel head-on and both vessels must give way.	Movie: See the action!
Encountering Sailing Vessels at Night - What the Lights Mean	Illustrations of Lights
A red and a green but no white light:When you see a red and a green light but no white light, you are approaching a sailing vessel head-on and you must give way.	Movie: See the action!
When you see only a red or only a green light, you may be approaching a sailboat under sail and you must give way. A sailboat under sail is always the stand-on vessel!	See only a red light... Movie: See the action!
	See only a green light... Movie: See the action!