The navigation rules require sound signals to be made under certain circumstances. Meeting, crossing and overtaking situations described in the Navigation Rules section are examples of when sound signals are required. Recreational vessels are also required to sound signals during periods of reduced visibility.
When operating on Inland Waters of the United States, vessels 39.4 feet/12 meters or more in length are required to carry on board a whistle or horn, and a bell.
Note: The requirement to carry a bell on board no longer applies to vessels operating on International Waters.
Any vessel less than 39.4 feet/12 meters in length may carry a whistle or horn, or some other means to make an efficient sound signal to signal your intentions and to signal your position in periods of reduced visibility.
Therefore, any vessel less than 39.4 feet/12 meters in length is required to make an efficient sound signal to signal your intentions and to signal your position in periods of reduced visibility.
Click here to view the US Coast Guard Navigational Rules
Sound Signals
Every vessel is required to carry some kind of efficient sound producing device to signal there intentions as outlined below.
Vessels are required to sound signals any time that they are in close quarters and risk of collision exists.
The term "short blast" means a blast of about one second.
The term "prolonged blast" means a blast of from four to six seconds.
The following signals are the only ones to be used to signal a vessel's intentions (inland rules only).
- One short blast - I intend to change course to starboard.
- Two short blasts - I intend to change course to port.
- Three short blasts - I am operating astern propulsion (backing up).
- Five or more short and rapid blasts - Danger or doubt signal (I don't understand your intent).
Note: Inland rules use sound signals to indicate intent to maneuver and a response should be received. In international rules the signals are given when the maneuver is being executed.
Click here to view the US Coast Guard Navigational Rules