There is very definitely a "load" when you shift a powerboat from neutral to forward or reverse: the RPMs drop, and sometimes the engine will stall under the relatively small load of turning the standard prop.
Accelerating increases the load, and therefore the noise. Measuring noise at a dock gathers gobbledegook—instead of meaningful numbers. The Trojan Horse law snuck-in legalized noise that was formerly illegal.
Except now, scofflaws can turn their noisy exhausts on and off, and on again, as a couple of us noticed last Saturday.
