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 are examples of when sound signals are required.
|If on State Waters or on Mississippi River, Missouri River, or Federal 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|
*Federal reservoirs in Iowa include Saylorville, Red Rock, Rathbun, and Coralville Reservoirs.
|If on Federally Controlled Waters|
|Less than 39.4 feet (12 meters) long (includes PWC)||Something such as handheld air horn, an athletic whistle, or an installed horn required|
|39.4 feet (12 meters) long or longer||Sound signal should be audible for one-half mile and should last for 4 to 6 seconds|