[slodave]

Think of airplanes when designing the rudder(s). Planes do not have large rudders, because at cruising speeds, they don't need a lot of surface area to turn. Air boats are almost the same, though, they do suffer from drag at low speeds more than airplanes do, so the surfaces have to be a little larger. Also, while taxing on the ground, a plane usually has a nose wheel that is attached to the rudder cable to help turn.