Ship lights, navigation lights & day shapes

Sailing vessel

Dead aheadStarboardAsternPortDead ahead

Signals

☀️ By day

🌙 At night

Lights on this vessel

Light	Colour	Arc	Range	Visible now

Remember

Red to red, green to greenIf you see her red sidelight, she sees yours. You are on passing courses.

If you see red, he has right of wayIf you have her red sidelight on your starboard side, it is you who must give way.

Only white?A single white light may be a sternlight – you are overtaking the vessel, and then you must always keep out of the way.

Red over green– sailing vessel at night. Optional all-round lights at the masthead of a vessel under sail alone.

Green over white – trawlerAll-round green over white: a trawler engaged in trawling. Keep out of the way.

Red over white – fishingAll-round red over white: a vessel fishing with nets or lines. Keep out of the way.

Day ≠ nightBy day the lights are off. The vessel then shows black shapes – e.g. two cones with points together for fishing.

Based on the International Regulations for Preventing Collisions at Sea (COLREG), Rules 20–25. Ranges in nautical miles (nm).

Overview: lights and day shapes for all vessel types

Here are the main lights at night and day shapes by day for each vessel type in the collision regulations. Choose a type to see it in 3D.

Vessel type	🌙 Lights at night	☀️ Day shape
Sailing vessel	Sidelights + sternlight (or a tricolour lantern under 20 m, or red over green at the masthead).	Under engine: cone point downwards.
Power-driven vessel	Masthead light, sidelights and sternlight. From 50 m: two masthead lights, the after one higher.	No day shape.
Fishing vessel	Red over white all-round lights. Sidelights and sternlight only when making way.	Two cones with points together.
Trawler	Green over white all-round lights. Sidelights and sternlight only when making way.	Two cones with points together.
Pilot boat	White over red all-round lights + sidelights and sternlight on pilotage duty.	At anchor: one black ball.
Vessel at anchor	One white all-round light forward (two from 50 m, the forward one higher).	One black ball forward.
Not under command	Red over red all-round lights (+ sidelights and sternlight when making way).	Two black balls in a vertical line.
Restricted in her ability to manoeuvre	Red–white–red all-round lights in a vertical line.	Ball–diamond–ball.
Vessel engaged in mineclearance	Three green all-round lights: at the masthead and at both yardarms.	Three black balls.
Dredging, diving or underwater operations	Red–white–red + two red on the obstructed side and two green on the side where it is safe to pass.	Ball–diamond–ball + two balls / two diamonds.
Constrained by her draught	Three red all-round lights in a vertical line.	Black cylinder.
Aground	Anchor light + two red all-round lights in a vertical line.	Three black balls in a vertical line.
Tug	Two masthead lights (three when the tow exceeds 200 m) + yellow towing light above the sternlight.	Diamond on tug and tow when the tow exceeds 200 m.
Vessel with a diver in the water	Red–white–red all-round lights in a vertical line.	Rigid replica of flag “A”.
Air-cushion vessel	Yellow flashing all-round light + lights as a power-driven vessel.	No day shape.
WIG craft	High-intensity all-round flashing red light when taking off, landing and in flight.	The red flashing light is also used by day.

Frequently asked questions about ship lights

Which lights must a sailing boat show at night?

A sailing vessel underway shows a green sidelight to starboard, a red sidelight to port and a white sternlight. Under 20 m they may be combined in a tricolour lantern at the masthead. If the boat is proceeding under engine, she must also show a masthead light like a power-driven vessel.

What do red over white and green over white mean?

Red over white all-round lights is a vessel fishing with nets or lines. Green over white is a trawler engaged in trawling. Both are engaged in fishing, and a pleasure craft must keep out of the way.

What is a day shape?

By day the lights are off, and vessels show black shapes instead – balls, cones, diamonds and cylinders – that tell you what the vessel is doing. For example, a vessel at anchor shows one ball, and a fishing vessel shows two cones with their points together.

How large is the arc of the sidelights, masthead light and sternlight?

The masthead light shows over 225° forward, each sidelight over 112.5° from right ahead aft on its own side, and the sternlight over 135° aft. If you only see a white light, it may be a sternlight – then you are overtaking the vessel and must keep out of the way.

Do you need to know ship lights for the Duelighedsbevis and Yachtskipper?

Yes. Lights, day shapes and steering rules are part of both the Duelighedsbevis and Yachtskipper af 3. grad. The ship-lights model here lets you turn the vessel, switch between day and night and test yourself in a quiz.