It feels sort of similar to sailing angled across the wind to me, though for that the water is playing the role of the wire holding you in place, and the wind is playing the role of the water driving it...,(reply>), The way I was thinking about it, if the Reaction Ferry wanted to change direction in the middle of a trip, that would be analogous to tacking, but a normal trip across the river would be analogous to sailing straight perpendicular to the wind.,(reply>), You are thinking of Tacking I think, but that still moves you forwards even if you are going against the wind. You could do this same thing with the wire if you used a sail with wind, the only problem is wind changes.