donít take this wrong but rotaries are the wrong engine for boats . They cant produce the torque needed to push a 8000+lb boat. Maybe a little fishing boat to beat your friends to the whole. They also cant handle the long run times. I am new to boating but can only guess that you cant push that type of rpm threw a drive without a trans or gear box witch robs torque of our already limited rotary even a 20b 3rotor cant make the needed torque.
Before you go yelling at me let me tell you some of my background. I tune and build turbo efi systems. Mostly imports including some wankles. We have a 2.0 liter Mitsubishi Evo in the shop that makes over 1000hp at the wheels. This car has also ran a traction limited 170mph ľ pass already. So I am no stranger to forced induction. We also have some friends from PR that have ran 7.10 ľ mile in a Toyota Starlet with a 13b. So I know what the power potential of these motors when running 60-70psi of boost and methanol.