I have a 12.5 foot mercury quicksilver inflatable boat and a 20 hp honda 4 stroke that I bought used. It seemed like a great deal and the owner was honest when he said that the package did not perform as well as he had hoped and that was why he was selling it. I figured I would have no problem figuring out what the problem was but I am stumped. Basically, whenever the boat gets on step it cups the water out so much the it creates a cavitation and I have to back off on the power. This turns into a series of fast/slow or I am simply stuck ideling along. I have tried over inflating the boat, all sorts of motor adjustments and different load configurations and nothing has helped. I have had people say that a planeing fin might help? I am thinking about cutting the transom down? I have thought about trying to find a lift that would help me lower the motor a little more plus it would help me run a little shallower. Any suggestions, ideas, history with a similar problem?