There are substantial problems with this method, of course. Current differences are likely to be small and variable, thus imparting little speed and requiring re-adjustment of the angle of the wing. Transmitting the forces along masts long enough to reach into regions of varying current is difficult as well. It may not be feasible. However, there is a certain elegance to this method of propulsion, and it would be truly magnificent for a seastead to sail, not drift, in the ocean's currents.