Mufflers and Noise Level Limits

Vessel operators may not hear sound signals or voices if the engine is not muffled adequately.

• Every vessel with an engine must be equipped with a muffler or underwater exhaust system that is in good working order and in constant operation to prevent excessive noise.
• A vessel must not exceed the following noise levels.
  • Measured using a stationary test: For engines manufactured before January 1, 1994, the maximum noise level is 90 decibels; for engines manufactured on or after January 1, 1994, the maximum is 88 decibels.
  • Measured from the shoreline: For all vessels, the maximum operational noise level is 75 decibels.
• You may not remove, alter, or otherwise modify a muffler or muffling system if the result is increased noise level.
• The use of a muffler cutout or a muffler bypass system is prohibited, except while engaged in organized racing events in an area designated for that purpose.
• To ensure the muffler is working properly and also protect against carbon monoxide poisoning, the vessel exhaust system should be inspected for wear, damage, and leaks.