For some reason, I believed a single freewheel between the left and right drivetrains would give us the functionality of a differential plus the capability to go reverse when underway in water. Eventually I figured out our differential would function only when turning right. When turning left, the wheels wouldn’t slip. So, rather than losing a rocket because the sea air corroded a fastener, I re-engineered the paddle wheel axle a third time to install a second freewheel.
We lose reverse in the water but gain maneuverability when on the boat ramp.