Could you make it even more efficient/*quick* if quick were needed, by altering the relative positions of the cable teathers on both ends... or even one end really?<br>You can easily pull a lever that snaps one cable into a forward position and another into a back one, giving a relative gradient in a sense - backwards. Much like a light-switch which could change both tether ends.<br><br>Side A - Forward, Side B - Back.<br>Get to side B, with A - Forward &amp; B - Back. Change them round... you'd have to have a snap mechanism to push the boat forward agaisnt the current &amp; a tether system to the side that you're on, but it'd make side to side faster. But obviously complicate things in turn!