Every vessel operating on U.S. inland waters is among the vessels required to carry sound signaling devices, but what you need depends on how long your boat is. Under 12 meters (about 39.4 feet), any efficient noisemaker will do. At 12 meters and up, you need a whistle that meets federal specifications. At 20 meters (about 65.6 feet), add a bell. At 100 meters (about 328 feet), add a gong. These thresholds come from the Inland Navigation Rules in 33 CFR Part 83 and apply to kayaks, sailboats, powerboats, and commercial ships alike.1eCFR. 33 CFR 83.33 – Equipment for Sound Signals (Rule 33)
Where the Rules Apply
The Inland Navigation Rules cover all vessels on U.S. inland waters: harbors, rivers, inlets, the Great Lakes, coastal bays, and any waterway inside the demarcation lines the Coast Guard draws between inland waters and the high seas.2Office of the Law Revision Counsel. 33 U.S. Code 151 – High Seas and Inland Waters Demarcation Lines Cross those lines seaward and the International Regulations for Preventing Collisions at Sea (COLREGS) take over. For anyone staying in bays, rivers, lakes, and near-shore waters, the Inland Rules are the ones that matter.
States can add their own boating safety requirements on top of the federal rules. They cannot subtract. If your state asks for less, the federal floor still applies.
Equipment by Vessel Length
The federal rule ties required equipment directly to vessel length, with four tiers:
- Under 12 meters (about 39.4 feet). No formal whistle or bell required. You must carry some means of making an efficient sound signal — a handheld air horn, a sports whistle, or even a plastic pea whistle, as long as it’s loud enough to alert nearby vessels.1eCFR. 33 CFR 83.33 – Equipment for Sound Signals (Rule 33)
- 12 meters or more. A whistle meeting the technical specifications in Annex III of the rules.
- 20 meters or more (about 65.6 feet). A whistle and a bell.
- 100 meters or more (about 328 feet). A whistle, a bell, and a gong. The gong’s tone must be distinct enough that it cannot be confused with the bell.1eCFR. 33 CFR 83.33 – Equipment for Sound Signals (Rule 33)
Propulsion type does not change the tier. Sailboats, powerboats, and commercial vessels follow the same length thresholds. The rules also allow a bell or gong to be replaced by other equipment with the same sound characteristics, provided the signal can still be sounded manually.
What Counts as a Whistle
For vessels 12 meters and up, “whistle” is a technical term, not a generic one. The device must have a fundamental frequency between 70 and 700 Hz and meet audibility standards that scale with vessel size, from 0.5 nautical miles for boats under 20 meters up to 2 nautical miles for vessels 200 meters or longer.3eCFR. 33 CFR 86.01 – Whistles Those audibility figures assume calm conditions and typical background noise; real-world range drops in heavy wind or high seas, and the regulation itself treats the numbers as approximate.
Placement is regulated too. A whistle must be mounted as high as practicable to reduce sound obstruction and limit hearing damage to crew. If a directional whistle is the vessel’s only whistle and is permanently installed, it must point forward.
What Counts as a Bell or Gong
Bells and gongs are governed by 33 CFR 86.02. Both must produce a sound pressure level of at least 110 dB at one meter, and both must be made of corrosion-resistant material that gives a clear tone.4eCFR. 33 CFR Part 86, Annex III – Technical Details of Sound Signal Appliances For vessels 20 meters or longer, the bell’s mouth diameter must be at least 300 millimeters (about 12 inches), and the striker must weigh at least 3 percent of the bell’s total mass. A power-driven striker is recommended, but the bell must always be capable of being rung by hand. On vessels 100 meters or longer, the gong is sounded from the stern while the bell is sounded from the bow, so the two signals help nearby vessels judge your position and length.
When You Actually Have to Use Them
Carrying the equipment is separate from sounding it. The rules require signals in two situations: maneuvering signals between vessels in sight of each other, and fog signals in restricted visibility. The fog rules are where bells and gongs earn their place. A vessel at anchor in fog rings its bell rapidly for about five seconds, every minute; on vessels 100 meters or longer, the bell rings at the bow and the gong immediately follows at the stern.5eCFR. 33 CFR 83.35 – Sound Signals in Restricted Visibility (Rule 35) A vessel large enough to require a bell but sitting at anchor in fog without one is both a hazard and in violation of federal law.
Penalties for Missing Equipment
The Coast Guard enforces these rules and can stop and inspect vessels on inland waters. For recreational vessels, the penalty framework sits in 46 U.S.C. § 4311. A non-willful violation, such as operating without required sound equipment, carries a civil penalty of up to $1,000, and the vessel itself can be held liable. A willful violation is criminal: a fine of up to $5,000, imprisonment for up to one year, or both.6U.S. Code. 46 USC 4311 – Penalties and Injunctions First-time offenders often get a warning or a lower fine in practice, but repeat violations and unsafe conditions are treated more seriously. Commercial vessels face additional enforcement under separate inspection regimes.
Practical Notes for Small-Boat Operators
If your boat is under 12 meters, the rule gives you flexibility, but the device you carry has to work when you need it. A depleted air-horn canister or a whistle buried in a locker does not satisfy the requirement. Carry a backup. A compressed-air horn as your primary and a plastic pea whistle clipped to a life jacket costs almost nothing and covers you if the horn fails.
Check sound equipment before every outing, especially compressed-air canisters, which lose pressure over time. If you operate in fog-prone areas or heavy traffic, consider a louder device than the rule strictly requires for your length. The 0.5-nautical-mile audibility figure for sub-20-meter vessels assumes ideal conditions that rarely exist on real water.