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Course Outline

Navigation lights at night

Navigation lights help you and other boaters determine which is the give-way vessel when encountering each other at night. These lights must be displayed from sunset to sunrise and during periods of restricted visibility, such as fog. There are four common navigation lights.

  • Sidelights: These red and green lights are called sidelights (also called 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 and is required on all power-driven vessels. (On power-driven vessels less than 39.4 feet in length, the masthead light and sternlight may be combined into an all-round white light; power-driven vessels 39.4 feet in length or longer must have a separate masthead light.) A masthead light must be displayed by all vessels when under engine power. The absence of this light indicates a sailing vessel because sailboats under sail display only sidelights and a sternlight.
  • 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. This light serves as an anchor light when sidelights are extinguished.
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