Audio drill
Learn the signals by ear
A fog signal is useful only if you recognise it before you see the vessel. Start with the restricted-visibility set, then mix in the Rule 34 manoeuvring and narrow-channel signals.
Listen first
What does this signal tell you?
No answers yet
In or near restricted visibility. Play it as often as you need, then choose the meaning. The notation stays hidden until you answer.
5 s
Durations and meanings follow International COLREG Rules 32, 34 and 35. Short means about one second; prolonged means four to six seconds. Check the current official text before relying on any rule at sea: USCG Navigation Rules.