3 ms·

I’m confused. Can they only operate this when the wind I perpendicular to the direction the ship wants to go?

• kpil 9y ago
  I suppose it works like ordinary sails, but without decent trim - the shape of the hull and rudder counterbalance the perpendicular force and you steer slightly crosswind to compensate for drift. You won't be able to go directly into the wind, as the forward component can't be too small. I guess you need to spin it in the right direction unless you want to go backwards...