Masthead light: white, 225°, from right ahead to 22.5° abaft the beam on each side. Sidelights: green to starboard, red to port, 112.5° each, right ahead to 22.5° abaft the beam. Sternlight: white, 135°, the rest. Masthead plus sidelights therefore covers exactly what the sternlight does not: see a low white alone and you are in her overtaking sector.
1. The stack (all-round lights in a vertical line) names her. 2. Mastheads say power-driven, and how long. 3. Sidelights say which way, and whether she is making way at all.
| Stack | Vessel | Day shape |
|---|---|---|
| Green over white | Trawling | Two cones, points together |
| Red over white | Fishing, not trawling (white all-round toward gear if it runs out over 150 m) | Two cones, points together (cone up toward the gear) |
| Red over red | Not under command | Two balls |
| Red, white, red | Restricted in ability to manoeuvre | Ball, diamond, ball |
| Red white red + two reds one side, two greens the other | Dredging or underwater ops: pass on the green side | Two balls / two diamonds |
| Three reds | Constrained by her draught | Cylinder |
| Three greens (masthead and both yardarms) | Mine clearance: keep 1000 m clear | Three balls |
| White over red (+ sidelights and sternlight underway, + anchor light at anchor) | Pilot vessel on duty | — |
| One white forward (second, lower, aft if 50 m+; deck lights 100 m+) | At anchor | Ball forward |
| Anchor lights + two reds | Aground | Three balls |
| Two mastheads in a line (three if tow over 200 m) + yellow over the sternlight | Towing. The tow shows sidelights and sternlight only | Diamond on both if over 200 m |
| All-round flashing yellow | Hovercraft skimming | — |
Red over red, the captain is dead. Red white red, restricted ahead. Red over white, fishing tonight. Green over white, trawling tonight. White over red, pilot ahead.
Sidelights and sternlight with no masthead light: sail. Under 20 m she may combine them in one tricolour at the masthead. Optional red over green all-round at the masthead, never with a tricolour. Motor-sailing: power-driven lights, cone point down by day. Power under 12 m: one all-round white plus sidelights. Under 7 m and under 7 knots: all-round white, plus sidelights if practicable. Sailing under 7 m, or under oars: the same lights if practicable, otherwise a torch ready to show in time.
Underway means not anchored, moored or aground, even if stopped. Making way means moving through the water. Masthead lights go with underway (power, towing, constrained by draught). Sidelights on a hampered vessel (fishing, NUC, RAM) go with making way. A pilot vessel keeps her sidelights whenever underway. At anchor, a restricted vessel adds anchor lights; a fishing vessel never does. Under 7 m at anchor clear of channels and anchorages, no light needed; under 12 m aground, no aground lights needed.
Lateral: red to port and green to starboard when entering, any rhythm. Fl(2+1) red or green: preferred channel, treat as the plain mark of that colour. Cardinals are white and quick: continuous north, Q(3) east, Q(6)+LFl south, Q(9) west, the count round a clock face; pass on the named side. Fl(2) white: isolated danger, water all round. Iso, Oc, LFl 10s, Mo(A) white: safe water. Yellow: special, see the chart. Al Bu/Y: new wreck, keep clear.
Hand-bearing compass on her lights, then again a minute or two later, at least three times. Steady bearing and closing range: collision course. Bearing drawing forward, toward your bow: she passes ahead. Drawing aft: she passes astern. Big ships and tows can still hit you with a slowly changing bearing.
Overtaking (coming up from abaft her beam, you see only her sternlight): keep clear, either side. Head-on, two power-driven: both to starboard. Crossing, two power-driven: the one with the other on her starboard side gives way, alters to starboard and passes astern; the other stands on. Sail against sail: port tack gives way; same tack, windward gives way. Pecking order: power gives way to sail, both give way to fishing, and everyone to NUC and RAM. Stand-on: hold course and speed, watch, and act yourself if she does not, but not to port for a vessel on your port side.
In sight: ● starboard, ●● port, ●●● astern, ●●●●● doubt. Narrow channel: ▬▬● / ▬▬●● I will overtake on your starboard / port, ▬●▬● agreed, ▬ blind bend. In fog every two minutes: ▬ power making way, ▬▬ power stopped, ▬●● everyone hampered (sailing included), ▬●●● last vessel of a tow. Intervals are maxima. At least every minute: bell 5 s at anchor (gong aft too if 100 m+), three strokes, bell, three strokes aground. Fishing or working at anchor: ▬●●, not the bell. Pilot may add ●●●●. Whistle from 12 m, bell from 20 m, gong from 100 m.
1–5 pick an answer, Enter moves on, P replays a signal, B binoculars, C takes a compass bearing, F fullscreen. Alt+←/→ change stage. Progress is saved in this browser.