All boaters should know the 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 backing up."
Sound signals let other boaters know where you are located during periods of restricted visibility, such as 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.
Navigation rules include the use of sound signals to communicate with other boaters.
(one short blast) tells other boaters "I intend to pass you on my port (left) side."
(two short blasts) tells other boaters "I intend to pass you on my starboard (right) side."
The other vessel will sound the same signal if in agreement with the proposed maneuver.
