Navigation lights: learn them at night

At night you do not see a ship, only its lights. To learn them you read a few points in the dark: what is out there and which way it is heading. Pick a vessel and a viewing direction below and the scene shows only the lights you would actually see from there.

Why you never see every light

Each light shines only into a fixed arc. The masthead light covers 225 degrees forward, each sidelight 112.5 degrees to its own side, the sternlight 135 degrees aft. See red and green together and the vessel is heading straight for you. See a single low white light and you are usually looking at a stern or a vessel at anchor.

Navigation lights at a glance

The vessels from the scene with their lights, under the collision regulations.

Power-driven vessel under 50 m

White masthead light forward, sidelights red to port and green to starboard, white sternlight aft (COLREGs Rule 23).

Power-driven vessel of 50 m or more

From 50 m two masthead lights, the after one higher than the forward one, plus sidelights and sternlight.

Sailing vessel under way

Under sail only sidelights and sternlight, no masthead light (Rule 25). With the engine running she shows the lights of a power-driven vessel.

Sailing vessel with tricolour

Under 20 m the sidelights and sternlight may be combined in a tricolour at the masthead.

Vessel at anchor under 50 m

One white all-round light forward, where it can best be seen (Rule 30).

Vessel at anchor of 50 m or more

From 50 m two white all-round lights, the forward one higher than the after one.

Not under command, no way on

Two red all-round lights in a vertical line; with no way on, no sidelights or sternlight (Rule 27).

Not under command, making way

Two red all-round lights, and when making way through the water also sidelights and sternlight.

Restricted in ability to manoeuvre

Red, white, red all-round lights in a vertical line; when making way also masthead light, sidelights and sternlight.

Trawler under way

Green over white all-round lights; when making way also sidelights and sternlight (Rule 26).

Fishing vessel, not trawling

Red over white all-round lights; when making way also sidelights and sternlight.

Pilot vessel on duty

White over red all-round lights; under way also sidelights and sternlight (Rule 29).

Constrained by draught

Three red all-round lights in a vertical line, in addition to the lights of a power-driven vessel (Rule 28).

Towing, tow up to 200 m

Two masthead lights in a vertical line and a yellow towing light above the sternlight (Rule 24).

Simplified for learning. The collision regulations and local rules are what count.