How to setup 12 ft tunnel hull

I have a scat cat type of 12 ft 2 seat tunnel hull and a 15 hp mercury long shaft 4 stroke motor
when I try to run it fast it just plows and tries to drop on a plane but as it does the motor seems to cavitate and shake and I feels like it is about to damage the transom.
Is a tunnel set up differently then a regulat boat hull? what must I do?

 

Most outboards with tunnels will shake and ventilate some. as far as the plowing, sounds like you have too much weight foreward. a 12 footer is pretty sensitive to weight distribution. Is your battery under the console? Try moving it aft, as well as the fuel tank. Finally, a poorly designed tunnel will cause a suction, but this usually pulls the stern down.

 

If it's an outboard, you can change the angle (motor - surface of the water) too

see here http://www.boaterexam.com/

 

The motor angle is set like the one pictured at the bottom but the boat plows along like the one in the middle. Am I running with too little hp (15)?