In periods of reduced visibility or whenever a vessel operator needs to signal his or her intentions or position, a sound-producing device is essential. The navigation rules for meeting head-on, crossing, and overtaking situations described in Unit 4 are examples of when sound signals are required.
Vessels less than 39.4 feet (12 meters) in length, which includes PWCs, are required to carry on board a whistle or horn or some other means to make an efficient sound signal to signal intentions or positions.
Vessels that are 39.4 feet (12 meters) or more in length are required to carry on board a whistle or horn, and a bell.
If on State Waters or on Mississippi River, Missouri River, or Federal Reservoirs*
* Federal reservoirs in Iowa include Saylorville, Red Rock, Rathbun, and Coralville Reservoirs.
Less than 16 feet long (Class I)
None required, but at least a whistle is recommended
16 feet long or longer but less than 26 feet long (Class II)
Whistle or other sound-producing device required
26 feet long or longer (Class III or IV)
Whistle or other sound-producing device and a bell required
If on Federally Controlled Waters
Less than 65.6 feet long (includes PWCs)
Whistle or horn audible for at least one-half mile required
65.6 feet long or longer
Whistle or horn and a bell audible for at least one mile required
Use the above chart to determine what is required based on your vessel’s length.