It's the Law: Required Equipment

Sound-Producing Devices

• Vessels less than 65.6 feet (20 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 announce intentions or positions.
• Vessels 65.6 feet (20 meters) or more in length are required to carry on board a whistle or horn, and a bell.

Some sound signals that you should be familiar with are:

Restricted Visibility

• One prolonged blast at intervals of not more than two minutes is the signal used by powerboats 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.

Warning

• One prolonged blast is a warning signal (for example, when coming around a blind bend or exiting a slip).
• Five (or more) short, rapid blasts signal danger or that you disagree with the other boater's intentions.