Horns, pots and pans, and other noisemakers aren’t just for birthday parties and New Year’s Eve celebrations. For boaters, it’s essential to have the proper “noisemakers” on board—and to know how to use them.
The cheat sheet below covers inland sound signals for power-driven vessels.
SOUND SIGNALS CHEAT SHEET
Sound Producing Devices by Boat Size:
- If your boat is less than 39.4 feet long, you are required to carry an efficient sound-producing device, such as a whistle, an air horn, or a bell.
- If your boat is between 39.4 feet to 65.6 feet long, you are legally required to carry:
- A whistle that’s audible for 1/2 nautical mile
- A bell with a minimum mouth diameter of 7.87 inches
Sound Signals for Common Maneuvers:
Short blast duration: approx. 1 second
Prolonged blast duration: approx. 4-6 seconds
- One Short Blast: Tells other boats, “I intend to pass you on my port (left) side.” In other words, when you’re approaching another vessel—either head-on or from behind—you will maneuver to leave them on your left side as you pass.
- Two Short Blasts: Tells other boats, “I intend to pass you on my starboard (right) side.” In other words, when you’re approaching another vessel—either head-on or from behind—you will maneuver to leave them on your right side as you pass.
- Three Short Blasts: Tells other boaters, “I’m backing up” or “I’m using astern propulsion.”
- Five (or more) Short Blasts: This rapid sequence of blasts is a DANGER signal. You are required to use the danger signal if you don’t understand another vessel’s sound signal—or if you feel their proposed maneuver is dangerous.
- One Prolonged Blast: This is a WARNING signal. It should be used when:
- You are leaving a dock or departing your slip—to signal that you are getting underway.
- You are coming around a blind bend and can’t see approaching vessels.
- One Prolonged Blast + Three Short Blasts: This sequence of blasts lets others know you are departing a dock in reverse. (This is a combination of signals noted above: 1 prolonged = getting underway; 3 short = backing up).
IMPORTANT: The sound signals listed in this Cheat Sheet must only be used when you are within half a mile of the other vessel(s)—and you can see each other by eye. In fog or other conditions of restricted visibility, you must adhere to the signals listed under Rule 35 of the USCG’s Navigation Rules. The information above reflects Inland Rules; International Rules may be different.