On your boat I would set the prop shaft at 3.5 inches below the boat to start with. Another thing you want to look at or have looked at is the prop itself. Make sure it has good cup in it and that the blades arent laid back or bent back. Most of the time you want to have a prop guy look at that part for you. Keep in mind, a little bit of blowout is ok and youo should always take off with the motor trimmed all the way down. With the motor tucked under all the way it will push the bow down to pop the boat up on plane.