To add a little more explanation, allows the motor to spin to max power while under driving the pump. Just connecting the motor to the pump would not allow the enging to reach max power...Hopefully that makes sense.This is for someone with a real high RPM race engine in their jet boat to reduce the RPMs down to a more efficient range, correct???
Or is this for someone with a small boat where the engine is positioned on top of pump, so a gearbox is required to connect the pump and engine???