Communicating With Sound Signals
What is a Sound Signal?
Sound signals used on the waterways are like the turn light indicators used to signal intentions on the highways. Sound signals are also like an automobile's horn used to let other drivers know you are near or to alert them of danger. All boaters should know proper sound signals, especially those boaters operating near commercial vessel traffic.
Sound signals are composed of short and prolonged blasts and must be audible for at least one-half mile:
- Short blast—about one second in duration
- Prolonged blast—4-6 seconds in duration
Sound signals can communicate a change in direction to other boaters.
- One short blast tells other boaters "I intend to pass you on my port (left) side."
- Two short blasts tell other boaters "I intend to pass you on my starboard (right) side."
- Three short blasts tell other boaters, “I am operating astern propulsion.” For some vessels, this tells other boaters, “I am backing up.”
Sound signals let other boaters know where you are located during periods of restricted visibility, such as extreme fog. If you hear the fog signal of a vessel you cannot see, slow to a minimum speed until you are sure there is not a risk of collision.
- One prolonged blast at intervals of not more than two minutes is the signal used by power-driven vessels when underway.
- One prolonged blast plus two short blasts at intervals of not more than two minutes is the signal used by sailing vessels.
Sound signals are used to warn other boaters or alert them to danger.
- One prolonged blast is a warning signal (for example, used when coming around a blind bend or leaving the dock).
- Five (or more) short, rapid blasts are used to signal danger or to signal that you do not understand or you disagree with the other boater's intentions.
Using Sound Signals When Encountering Other Vessels
Navigation rules include the use of sound signals to communicate with other boaters. The other vessel will sound the same signal if in agreement with the proposed maneuver.
TOOT (one short blast) tells other boaters "I intend to pass you on my port (left) side."
TOOT TOOT (two short blasts) tells other boaters "I intend to pass you on my starboard (right) side."