i have been rebuilding a 17' rib-rigid inflatable boat.it is rated at 90 hp and 12 person compability-i put a 85 hp suzuki with 20" transom. the boat is a deep v and in the last 18" the bottom has a small triangle to plane on. the problems: should the cavitation plate be underwater? it planes now. Does the motor need to be deeper? the bottome of the boat is the same height as the cavitation plate. at full blast when i go across a boat wake the motor will cavitate and high rev. i put a dolphin fin on it and didn't seem to work to any better. I have a 15 pitch 3 blade propeller and have a light boat with little load shoud i use a different propeller? thanks for any input gene b.