Navigation lights

What vessel is that?

22 cards. Each shows a vessel’s lights from ahead and astern, and from abeam where that differs; turn the card for what she is and the rule that says so. Tap the card or press space to turn it, and use the arrows to move on.

Bow / head-on

Port side

Starboard side

Stern / overtaking

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All 22 cards as a list

Power-driven vessel underway (< 50 m): Rule 23(a) Masthead light forward, sidelights (red to port, green to starboard) and a sternlight. The second masthead is optional under 50 m.
Power-driven vessel underway (≥ 50 m): Rule 23(a)(ii) Two masthead lights, the after one higher than the forward one, plus sidelights and a sternlight.
Air-cushion vessel (non-displacement mode): Rule 23(b) The lights prescribed for a power-driven vessel in Rule 23(a), plus an all-round flashing yellow light (drawn steady here; at sea it flashes).
Power-driven vessel < 7 m (≤ 7 knots): Rule 23(d)(ii) In lieu of the Rule 23(a) lights, a single all-round white light. Sidelights shall also be shown if practicable.
Sailing vessel underway: Rule 25(a) Sidelights and a sternlight, no masthead light. Under 20 m these may be combined in a tricolour at the masthead (Rule 25(b)). Red-over-green all-round lights may be added at the masthead (Rule 25(c)), but never together with a tricolour.
Sailing vessel: optional masthead lights: Rule 25(c) Red-over-green all-round lights at or near the masthead identify a sailing vessel underway. Cannot be combined with the tricolour.
Sailing vessel < 20 m: combined lantern: Rule 25(b) In a sailing vessel of less than 20 m the sidelights and sternlight may be combined in one lantern carried at or near the top of the mast.
Vessel at anchor (< 50 m): Rule 30(b) One all-round white light where it can best be seen. By day: one black ball forward.
Vessel at anchor (≥ 50 m): Rule 30(a) Two all-round white lights: one forward, one near the stern and lower than the forward one.
Not Under Command (NUC): Rule 27(a) Two all-round red lights in a vertical line: a vessel unable to manoeuvre as required by the Rules. Day: two black balls.
Restricted in Ability to Manoeuvre (RAM): Rule 27(b) Red-white-red all-round lights vertically. Day: ball-diamond-ball. Used for dredging, cable-laying, replenishment, etc.
RAM: dredging / underwater operations: Rule 27(d) The red-white-red RAM lights, plus two all-round red lights marking the side where an obstruction exists and two all-round green lights marking the side on which another vessel may pass.
Vessel engaged in mine clearance operations: Rule 27(f) The lights of a power-driven vessel (Rule 23), or of a vessel at anchor, plus three all-round green lights: one near the foremast head and one at each end of the fore yard. Dangerous to approach within 1000 m of her.
Constrained by Draught (CBD): Rule 28 Three all-round red lights in a vertical line, in addition to the normal lights for a power-driven vessel. Day: a black cylinder.
Vessel trawling: Rule 26(b) Green-over-white all-round lights. When making way, also sidelights and sternlight. Day: two cones, apexes together.
Vessel fishing (not trawling): Rule 26(c) Red-over-white all-round lights. Outlying gear over 150 m: an additional all-round white light in its direction.
Pilot vessel on duty: Rule 29 White-over-red all-round lights at the masthead, plus sidelights and sternlight when underway, or anchor lights when at anchor.
Towing: tow ≤ 200 m: Rule 24(a) Two masthead lights in a vertical line, sidelights, sternlight and a yellow towing light above the sternlight.
Towing: tow > 200 m: Rule 24(a)(i) Three masthead lights in a vertical line instead of two, plus sidelights, sternlight and yellow towing light. Day: a diamond on tug and tow.
Pushing ahead / towing alongside: Rule 24(c) Two masthead lights in a vertical line, sidelights and a sternlight: no yellow towing light (that is only carried when towing astern).
Vessel or object being towed: Rule 24(e) Sidelights and a sternlight. When the tow exceeds 200 m, a diamond shape where it can best be seen.
Vessel aground: Rule 30(d) Anchor light(s) plus two all-round red lights in a vertical line. Day: three black balls in a vertical line.

Day shapes

By day, vessels show black shapes instead of lights. Read the shapes, then open the card for what she is.

One black ball in the fore part

Vessel at anchor Rule 30(a)(i)

A vessel at anchor shows one ball in the fore part, where it can best be seen.

Two black balls in a vertical line

Vessel not under command Rule 27(a)(ii)

Two balls or similar shapes in a vertical line, where they can best be seen.

Ball, diamond, ball in a vertical line

Vessel restricted in her ability to manoeuvre Rule 27(b)(ii)

Three shapes in a vertical line: the highest and lowest balls, the middle one a diamond.

A black cylinder

Vessel constrained by her draught Rule 28

A power-driven vessel constrained by her draught may show a cylinder where it can best be seen.

Two cones with their points together, one above the other

Vessel engaged in fishing (trawling or otherwise) Rule 26(b)(i) and (c)(i)

Two cones with their apexes together in a vertical line. A vessel fishing other than trawling, with outlying gear more than 150 m out, adds a cone point up in the direction of the gear (Rule 26(c)(ii)).

A black diamond

Towing, with a tow longer than 200 m Rule 24(a)(v) and (e)(iii)

When the length of the tow exceeds 200 m, the towing vessel and the vessel or object being towed each show a diamond shape where it can best be seen.

Three black balls in a vertical line

Vessel aground Rule 30(d)(ii)

A vessel aground shows three balls in a vertical line, where they can best be seen.

A cone, point down, forward

Sailing vessel also under engine Rule 25(e)

A vessel proceeding under sail when also being propelled by machinery shows forward, where it can best be seen, a conical shape with the apex downwards.

The rules behind the lights: Rule 23 onwards, in the lessons.

A training aid, not the official text. The COLREGs are an IMO convention, and your national authority publishes the version that applies in its waters. Check the rules themselves before you rely on them at sea. Download the rules.