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AhaBulb: Stuff Everyone Should Know · ahabulb.com/boat-sound-signal-under-12m

A boat under 12 meters (39.4 feet) needn't carry a regulation whistle. What must it have?

Some other way to make an efficient sound signal.

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  1. Nothing at all
  2. Some other means of making an efficient sound signal ✔
  3. A bell and a gong

Why: Inland Rule 33 says vessels under 12 meters don't have to carry the regulation whistle and bell, but must have some other way to make an efficient sound signal, such as a horn.

Huh, didn't know that: Vessels 12 meters and longer need a whistle, and those 20 meters and longer need a bell as well.

The dad joke
Why did the boat horn see a doctor? It was feeling a little hoarse.
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References

Answer: Some other means of making an efficient sound signal. Inland Rule 33 says vessels under 12 meters don't have to carry the regulation whistle and bell, but must have some other way to make an efficient sound signal, such as a horn.

  1. 33 CFR 83.33 Equipment for sound signals, Inland Rule 33 (eCFR) www.ecfr.gov/current/title-33/section-83.33
    she shall be provided with some other means of making an efficient sound signal.
    Checked 2026-10-08.

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