^^Same as Grub. I've seen old variable pitch props. These had a bellville spring actuator that kept the blades at full high pitch when relaxed, and flattened under high load for hole shot acceleration. Then as torque decreased and speed increased the springs pushed the blades into a higher pitch state.
With your engine and boat size I think you'd have better luck dialing in the correct prop pitch for your needs. Lower pitch = better hole shot and lower speed power, but lower top end speed and possible engine over rev. Higher pitch = the opposite.
Elaborate on your goals, current RPM/speed performance. WOT speed and engine rpm are key pieces of info.
