Navigation Sound Signals

Equipment, Uses, & Examples

Take the quiz below before you view the video.

Then view the video and take the quiz again to see how much your score improves!

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Sound Signals Summary

Review the below summary of sound signals & their patterns.

Key Sound Signal Points on the Water
Short blasts: One (1) second long
Long blasts: Four to Six (4-6) seconds long
  • One (1) short blast indicates going right
  • Two (2) short blasts indicate going left 
  • Three (3) short blasts indicates astern propulsion
  • Five (5) or more short blasts indicates disagreement or danger
  • Matching response indicates mutual agreement

Blind Curve or Change of Status (e.g., Departing a Slip)
  • One (1) long blast
Restricted Visibility – Power Boat
  • One (1) long blast every 2 minutes if underway
  • Two (2) long blasts every two minutes if stopped.

Restricted Visibility – Sail Boat
Anchored, Fishing, and Restricted Ability to Maneuver
  • One (1) long and two (2) short blasts every two minutes.


Take a Quiz on Sound Signals

1. When using a whistle, a "short blast" is how many seconds in duration?

About one
Two to three
Over three but under five
Any blast that can be heard

2. When using a whistle, a "prolonged blast" is how many seconds in duration?

One to two
Four to six
Eight to ten
Over ten

3. When two vessels are in a crossing situation, if you intend to alter your course to port (turn left) leaving the other vessel to starboard (your right) you should sound which signal?

A prolonged blast
Two short blasts
One short blast
Long and short blast

4. If you are backing your boat how do you indicate operating astern propulsion?

Blink your navigation light
Give three short blasts
Give a prolonged blast
No signal is needed

5. In "Restricted Visibility" (for example seeing is difficult because of fog, rain, snow or smoke) and you are operating a powerboat underway what should the operator turn on?

Navigation lights and use your radio to hail the U.S. Coast Guard
Search light and blink your navigation lights every two minutes
Navigation lights and produce one prolonged blast every two minutes
Special flashing yellow light and produce a series of blast every 30 minutes