And to keep things interesting, my last boat was a 1650 Crestliner with 2 different horsepower ratings with both indicated on the capacity plate of the boat.
U.S. Coast Guard rated the boat for 90 HP, which it had, but Canadian Coast Guard only rated it for 50 HP.
I called CCG and was told Canada always under rated the maximum power but didn't know why. He did say though, that if I exceeded the 50 HP rating and had an at fault accident with the boat, I would probably have a hard time getting the insurance company to pay any $$$$.