Under power or under sail: what your boat shows
1The lesson in plain words
A masthead light marks power. Under sail, show sidelights and a sternlight, or an allowed alternative. When the engine propels you, change to power-driven lights.
Under power
A power-driven vessel is any vessel propelled by machinery. Underway she shows a masthead light forward, sidelights and a sternlight (Rule 23). A second masthead light, aft of and higher than the first, is required at 50 m or more and optional below. Underway means not at anchor, made fast to the shore or aground.
Small motorboats
Under 12 m you may instead show an all-round white light and sidelights (Rule 23(d)). Under 7 m, with a top speed of 7 knots or less, an all-round white light is enough, with sidelights if practicable. On boats under 20 m both sidelights may be combined in one lantern on the centreline. On power-driven boats under 12 m, a masthead or all-round white light carried with sidelights must be at least 1 m above them (Annex I).
Under sail
A sailing vessel underway shows sidelights and a sternlight, and no masthead light (Rule 25). Under 20 m these may be combined in one tricolour lantern at or near the top of the mast, where waves and sails hide it less. She may add red over green all-round lights near the masthead, but never together with the tricolour.
Motor-sailing
Once the engine drives the boat, even with sails up, you are a power-driven vessel. Switch off the tricolour. Show a masthead light, which yachtsmen call the steaming light, with sidelights and a sternlight. Under 12 m, an all-round white and sidelights also comply. By day, show a cone, point down, forward (Rule 25(e)). An engine idling in neutral to charge batteries is not propelling you.
The smallest craft
A sailing boat under 7 m shows sailing lights if practicable. If not, she must have a white torch or lighted lantern ready, shown in time to prevent collision (Rule 25(d)). A boat under oars, such as a rowing dinghy, may show sailing lights; if not, the same ready white light applies. Full text: /colreg/rule-23 and /colreg/rule-25.
2Key data
- Standard power-driven lights
- Masthead, sidelights, sternlight; second masthead at 50 m or more
- Power under 12 m
- May show all-round white + sidelights instead
- Power under 7 m, max 7 kn
- All-round white; sidelights if practicable
- Sail under 20 m
- Tricolour at or near the masthead allowed
- Motor-sailing
- Power-driven lights; by day a cone, point down
- Sail under 7 m
- Sailing lights if practicable; otherwise a white torch ready
3Key points
- 1
A white masthead light forward over 225° marks a power-driven vessel.
- 2
Under 12 m a power-driven boat may show an all-round white light and sidelights.
- 3
Under sail: sidelights and sternlight; under 20 m they may be one tricolour.
- 4
Engine propelling, even with sails set: switch off the tricolour and show power-driven lights.
- 5
Never show red-over-green all-round lights together with a tricolour.
4Frequent mistakes
Wrong: Leave the tricolour on when you start motoring at night.
Right: Motoring makes you power-driven. Switch to the steaming light, sidelights and sternlight.
Wrong: Show the tricolour together with the deck-level sidelights for extra safety.
Right: Show one set: either the tricolour or the separate sidelights and sternlight, not both.
Wrong: Any motorboat under 7 m may show just an all-round white light.
Right: Under 7 m and with a maximum speed of 7 knots or less, show an all-round white and sidelights if practicable. Faster boats need sidelights too.
5Practice case & exam keys
Sailing your 10 m yacht at night with the tricolour on, the wind dies and you start the engine and put it in gear, leaving the mainsail up.
Show the answer
You are now a power-driven vessel, so the tricolour must go off. Switch on the steaming light, with the deck-level sidelights and the sternlight; under 12 m an all-round white and sidelights would also comply. Other vessels now read you correctly as power-driven and apply the right rules. By day, you would hoist a cone, point down, forward.
Exam keys
- Power-driven: masthead light, sidelights, sternlight; under 12 m all-round white and sidelights allowed.
- Under 7 m and max 7 kn: all-round white, sidelights if practicable (Rule 23(d)).
- Sail: sidelights and sternlight; tricolour under 20 m; red over green optional, never with the tricolour.
- Motor-sailing: power-driven lights by night, cone point down by day.
Finish this unit
When you've read it, match the terms, then answer three questions. Get them all right to finish the unit; opening the page alone doesn't count.
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