Navigation lights are mandatory colored, angled lights (red, green, white) used on boats at night or in low visibility to prevent collisions, indicate direction of travel, and identify vessel type. They allow vessels to determine the orientation of others, with specific configurations defining whether a boat is under sail, power, or at anchor.

Key Navigation Lights
Sidelights: Red (port/left) and green (starboard/right) lights, typically visible from dead ahead to aft on their respective sides.

Stern Light: A white light placed at the stern (rear), visible (or on each side from behind).

Masthead Light: A white light shining forward and to both sides, required for power-driven vessels (often on the mast or front).

All-Round Light: A white light visible from, often used for anchoring or on small boats.

Sailing vs. Power Regulations
Under Sail: Sailboats under sail alone display red/green sidelights and a white stern light. They do not show a masthead light.

Under Power: A sailboat using an engine is considered a power-driven vessel and must display a masthead light, stern light, and sidelights.

At Anchor: Vessels at anchor show an all-round white light, while sidelights are extinguished.