I was thinking about adding a pedal powered propeller to a kayak and I had an idea:Use a hydraulic pump/motor combo to simplify the design. That way I could have the pedals in front of me and easily route some hydraulic lines to a propeller in the back. I came across this gear driven hydraulic pump at Northern tools. It weighs less than 7 lbs which is nice. I was wondering if it would be possible to use two of these pumps together with one driving the other. It seems like it should work. The pedals could drive one pump and the other will act as a motor. I'm worried that the pump will not work as a motor. A gear driven pump should be able to act as motor, correct?