Propeller design!!!! PROBLEM

Its not a good way of reducing pitch, it is not reducing pitch.

It is reducing the bite and lowering the amount of water passing through the blade reducing efficiency which will increase RPM without increase in thrust.

Slipping the clutch on a car is not the same as changing down a gear yet both increase RPM.

 

I don't think that "bite" is a very accurate way of describing how a propeller operates. The propeller blades will be operating at a certain angle of attack based on RPM and inflow speed. Increasing RPM increases angle of attack if the inflow speed remains the same. What he needs to do is either decrease the angle of attack with increased RPM (depitching) or reduce the blade section loading even with the higher AOA (reverse cup). In either case the boat will not go any faster, this is a change simply to allow the engine to reach rated RPM.