Just to put a fine point on how much difference a smooth bottom can make, I documented the difference a couple of years ago on my 33' trimaran
. I was going to do a super smooth bottom job, so first I pressure washed the old bottom paint
. Then I launched the boat, motored up and down our canal system at exactly 2500 rpm
during slack water
. I noted the speed during the passes and averaged the number.
After doing a month long super smooth bottom job which included burnishing the paint
and using a slippery coating, I launched again and repeated the slack water speed trial at the exact same engine
The boat went a full 15% faster with the new bottom. No other differences.