 In addition the "duck tail" transom, prop and rudder arrangement was better suited to diesel propulsion than the sail-optimised hulls of older types, though they do suffer from a pronounced "walk" effect when running aft.Typically they can carry through water, the hydrodynamics of the hull not being suited to higher speeds.In commercial use the hold was originally covered by duck boards, wooden panels which could be removed to expose the hold for loading.