Single-letter signals by light and sound, and SOS
1The lesson in plain words
A few single letters by lamp say a lot, fast. Ten of them must not be sounded except as the COLREGs require, because they are COLREG sound signals.
Letters worth knowing
U ··– ‘You are running into danger’. L ·–·· ‘You should stop your vessel instantly’. K –·– ‘I wish to communicate with you’. X –··– ‘Stop carrying out your intentions and watch for my signals’. V ···– ‘I require assistance’. W ·–– ‘I require medical assistance’. O ––– ‘Man overboard’. D –·· ‘Keep clear of me; I am manoeuvring with difficulty’.
Letters and the COLREGs
The Code marks B, C, D, E, G, H, I, S, T and Z with an asterisk. By sound, they may be made only in compliance with the COLREGs, because they match COLREG whistle signals.
SOS and landing signals
SOS, ···–––···, by light or any other method is a distress signal in COLREG Annex IV. The life-saving signals referred to in SOLAS use letters to guide small boats landing persons in distress. K by light or sound means ‘This is the best place to land’. S means ‘Landing here highly dangerous’; S followed by R or L adds that a better place lies to the right or left in the boat’s direction of approach.
How to practise
Practise in pairs indoors, with the light hidden from outside view. Use a torch for ten minutes. Start with SOS and the letters above, then mix them. Your partner reads each symbol aloud and gives its meaning. Swap roles. Keep the timing clear before increasing speed.
2Key data
- U ··–
- You are running into danger
- L ·–··
- You should stop your vessel instantly
- K –·–
- I wish to communicate with you
- V ···– / W ·––
- I require assistance / I require medical assistance
- By sound only per COLREG
- B, C, D, E, G, H, I, S, T, Z
- Landing signals: right/left in the boat’s direction of approach
- K best place to land; S dangerous; S+R / S+L better place right / left
3Key points
- 1
U, L, K, X, V, W, O and D are the single letters you are most likely to need by lamp.
- 2
Never sound the asterisked letters except as the COLREGs allow.
- 3
SOS by light is a COLREG Annex IV distress signal.
- 4
K and S are also landing signals for small boats with persons in distress.
4Frequent mistakes
Wrong: Sound D, –··, on the whistle to ask a nearby ship to keep clear while you manoeuvre.
Right: Send D’s Code meaning by lamp. Sound an asterisked letter only when the COLREGs authorise that sound signal.
Wrong: K always means “I wish to communicate with you”.
Right: Context matters. In the life-saving landing signals, K means “This is the best place to land”.
Wrong: D by lamp means ‘I am in distress’.
Right: D means ‘Keep clear of me; I am manoeuvring with difficulty’. Distress by light is SOS.
5Practice case & exam keys
From the shore, you guide a lifeboat that wants to land survivors on a beach. The surf where she is heading is heavy, but a sheltered cove lies 300 m to the right as she approaches. What can you signal by lamp?
Show the answer
Send S, ···, followed by R, ·–·: ‘Landing here highly dangerous; a better place lies to the right in your direction of approach.’ When she reaches the cove, signal K, –·–, ‘This is the best place to land’, from the landing point. Use VHF too if she has a radio.
Exam keys
- U ··– running into danger; L ·–·· stop instantly; K –·– wish to communicate.
- Asterisked B C D E G H I S T Z: by sound only in compliance with the COLREGs.
- SOS ···–––··· is a distress signal under COLREG Annex IV.
- Landing signals: K best place to land; S landing highly dangerous.
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