The Handbook of Iowa Boating Laws and Responsibilities

The Official Boating Handbook of the Iowa Department of Natural Resources - Web Version

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It's the Law

Mufflers and Noise Limits

The exhaust of every internal combustion engine on any powerboat must be effectively muffled by equipment constructed and in use to reasonably muffle vessel noise.

Powerboats must meet the following SAE sound level tests.

  • Stationary sound level test: Engines manufactured before January 1, 1993, must not exceed a noise level of 90 dBA. Engines manufactured on or after January 1, 1993, must not exceed a noise level of 88 dBA.
  • Shoreline sound level test: Engines must not exceed a noise level of 75 dBA.

All muffling devices used on powerboats must be in good working order and in constant operation to prevent excessive or unusual noise.

The use of cutouts is prohibited, except for vessels competing in an authorized marine event.