To run E85, yes you do need to re-jet your carbs. Depending on the engine you may need to upgrade your fuel system, because you need to burn approximately 30% more at the same power level.

It would not be good for your run of the mill motors. People running 1000 hp engines on race gas, though, could save a lot of money running E85.

Fuel vaporization with Ethanol varies a lot due to temperature, which might require some re-tuning. I would think that the range of temperatures boats operate in would be constant enough to come up with a "good enough" tune, though. Plus even high hp boat motors aren't as close to the ragged edge as alcohol drag cars.

A lot of engine manufacturers are also increasing jet sizes slightly to account for E10.

hmm, i might have to check this E85 out for the supercharged ski's been running 110l for the increased boost, but this sounds like it might be worth a shot.

Check your local Top alcohol class draggers...