Collision Regulations: Sound Signals

Marine sound signals have three purposes:

To indicate the presence of a vessel and define its type or status during periods of reduced visibility.
To broadcast a vessels actions to other vessels
Provide an alert or warning

Sound signals consist of patterns of long and short blasts. Please read through the content below.

A Short Blast: Approximately 1 second duration.

A Long Blast: Between 4 - 5 seconds duration.

Sound signals during periods of reduced visibility should be activated at intervals of not more than 2 minutes unless specified.

I am altering course to starboard.

I am altering course to port.

I am operating my engines astern.

Beware, this means that the engines are operating astern, but the vessel may still be moving forward under its momentum and slowing down. For a very large vessel, the engines may be going astern for a long time before it starts making way in reverse.

I do not understand your intentions.

Used to warn a vessel that has presented as a collision risk, and not taken action within the rules to make their intentions clear and take action to avoid a collision.

These sound signal demonstrations are also really good for dealing with telemarketers. I would recommend the 5 short blasts in those situations!