What Are Sound Signals (Whistle Rules)?
One short for “I am altering course to starboard”, five short for “I do not understand your intentions” - the universal language of the whistle, and the key fact that the five short blast is the most important of all.
Sound signals at sea are the universal language of short and long whistle blasts. The whistle is faster than VHF and the only form of communication that reaches everyone at once. In the small-boat world, it is enough to know the few that are most useful.
The table below sets out the basic manoeuvring signals.
Whistle signals
Signal | Meaning |
|---|---|
1 short | I am altering course to starboard |
2 short | I am altering course to port |
3 short | I am operating astern propulsion |
5+ short | I do not understand your intentions / I am in doubt (warning!) |
1 long | I am here (blind bend, narrow exit) |
The two most useful are five short and one long. Five short from a ferry means “I do not understand what you are doing and I am concerned”; the reply is not an argument, but to make your intentions clear, namely a definite course alteration.
A boat without a whistle is not acceptable: if the horn fails, a hand-held foghorn must be carried on board, and the rules require it. A quick-reference card can be put up in the cockpit: 1 starboard, 2 port, 3 astern, 5 I do not understand, long I am here.