MI HB6315

Requires all motorboats operated on Michigan waters to be equipped with a permanently affixed muffler or underwater exhaust system that produces no more than 90 dB(A) during stationary testing or 75 dB(A) during shoreline measurement.

Authorizes peace officers to request sound level tests of motorboats using SAE J2005 and SAE J1970 procedures to enforce compliance with noise standards.

Prohibits manufacturers from selling motorboats for use in Michigan unless equipped with compliant mufflers or exhaust systems meeting the specified decibel limits.

Exempts motorboats participating in sanctioned races, manufacturer testing/development, and historic vessels from the noise requirements.

Changes violation penalties from misdemeanor (up to 90 days imprisonment and fine) to state civil infraction with fines of $100-$500, with fines waivable if motorboat is brought into compliance before court appearance.