Why are some stinkpots much louder than others?

[scottie]

Its still an unnecessary opening remark

 

[johnalison]

It’s not only the Morphy-Richards that make a lot of noise. Some of the noisiest boats I have met have been of the Nelson hull type, and their generally lower speed sometimes means that the drone can seem to go on for ever.

 

[Farmer Piles]

Seagull outboards!! Remember those bare flywheel, noisy days??