Lights and shapes tell other vessels what you are, how big you are and what you are doing. Lights are shown from sunset to sunrise (and in restricted visibility, day or night). Shapes are shown by day.
Basic lights (Rule 21)
- Masthead light: white, 225-degree arc, shown ahead.
- Sidelights: green on the starboard side, red on the port side, each 112.5 degrees.
- Sternlight: white, 135 degrees.
- Towing light: yellow, with the same characteristics as the sternlight.
- All-round light: shows over 360 degrees.
Power-driven vessel underway (Rule 23)
Masthead light forward, a second masthead light abaft and higher (vessels of 50 m or more), sidelights and a sternlight.
Towing and pushing (Rule 24)
Additional masthead lights (two or three, depending on the length of the tow) and a yellow towing light.
Sailing vessels (Rule 25)
Sidelights and a sternlight. Small sailing vessels may show a combined lantern.
Fishing vessels (Rule 26)
- Trawling: green over white all-round lights.
- Other fishing: red over white all-round lights.
Not under command and restricted in ability to manoeuvre (Rule 27)
- NUC: two red all-round lights in a vertical line; by day two black balls.
- RAM: red-white-red all-round lights in a vertical line; by day ball-diamond-ball.
Constrained by draught (Rule 28)
Three red all-round lights in a vertical line (optional); by day a cylinder.
Pilot vessels (Rule 29)
White over red all-round lights.
Anchored and aground (Rule 30)
At anchor: an all-round white light forward (and a second aft for vessels of 50 m or more); by day one black ball. Aground: the anchor lights plus two red all-round lights; by day three black balls.
Learning tip
Do not only memorise the lights. Draw what you would see: is the vessel showing you green or red, and how are the masthead lights aligned? Sketching helps in both exams and real watches.
The visibility ranges of lights depend on vessel length and are set in Rule 22.