My CVX-16 does not get up on a plane until 20 MPH with the 115 HP Johnson. Tuck the motor in as close to the hull as you can to the transom, shift weight to the front, and use a low pitch prop for fine adjustment of motor speeds. Maybe use a four blade prop. And get an accurate GPS. I doubt your boat will plane at 11.5 MPH. The best you can do is plow at this speed.