Sound signals

Familiarise yourself with what different sound signals mean. The more common sound signals you may hear are:

Click on the links to listen to the sound files:

• one short blast: “I am altering my course to starboard”
  
• two short blasts: “I am altering my course to port”
• three short blasts: “I am operating a stern propulsion”
• five short blasts: “I am in doubt about your action taken to avoid collision”
• one long blast: “I am nearing a bend where another vessel may be obscured by an intervening obstruction”

 NB: If you hear 5 short blasts, the master and pilot on the ship are trying to tell you that they are concerned about how close you are, or are concerned with the course and speed you are following. You should at the very least make your intentions obvious, allow sufficient searoom for the ship’s safe passage, and preferably open the distance between yourself and the large vessel by moving away as quickly as possible.

Definitions

Whistle – efficient sound apparatus capable of making ‘short’ or ‘prolonged’ blasts.

Short blast – about 1 second duration

Prolonged blast – 4 to 6 seconds duration

Manoeuvring and warning signals – Rule 34

Whistle signals may be supplemented by light signals using the same code.

‘I am altering my course to starboard.’

‘I am altering my course to port.’

‘I am operating astern propulsion.’

‘I intend to overtake you on your starboard side.’

‘I intend to overtake you on your port side.’

The vessel about to be overtaken indicating its agreement.