Tom has a a cardinal rule point here.... Whenever I brought a prop to Don Hendrich, the first thing he would ask me is how high my rooster tail was. Typically, if you can see the spray over the hood of an OMC motor under full power, you need to lower your motor, or figure out whats going on before you can get your set up to work. So, if the rooster tail is over 5' off water, you need to set the motor lower because the prop blades are throwing too much in the air rather than thrust behind the boat....