The Handbook of Missouri Boating Laws and Responsibilities
The Official Boating Handbook of the Missouri State Highway Patrol, Water Patrol Division - Web Version
Table of Contents
The following requirements apply to vessels operating on Missouri state waters.
- Vessels more than 16 feet but less than 40 feet in length are required to carry on board a whistle or horn to make an efficient sound to signal intentions or positions.
- Vessels that are 40 feet or more in length are required to carry on board a whistle or horn and a bell.
The following requirements apply under federal laws on federally controlled waters.
- Vessels less than 39.4 feet (12 meters) in length, which includes PWC, must have some way of making an efficient sound signal. Examples are a handheld air horn, an athletic whistle, an installed horn, etc. A human voice is not acceptable.
- Vessels that are 39.4 feet (12 meters) or more in length must have a sound-producing device that can produce an efficient sound signal. The sound signal should be audible for one-half mile and should last for 4 to 6 seconds.
Some common sound signals that you should be familiar with as a recreational boater are as follows.
- 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 sailboats under sail.
- One prolonged blast is a warning signal (for example, used when coming around a blind bend or exiting a slip).
- Five (or more) short, rapid blasts signal danger or signal that you do not understand or that you disagree with the other boater’s intentions.