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It's the Law

Sound-Producing Devices

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.

If on State Waters

Less than 26 feet long (includes PWC) None required, but highly recommended
26 feet long or longer Whistle, horn, or other sound signal required

If on Federally Controlled Waters

Less than 65.6 feet long (includes PWC) 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

Sound Signals

Sound producing devices

Some common sound signals that you should be familiar with as a recreational boater are as follows.

Restricted Visibility

  • 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.