Screw Vessel

a sea vessel driven by a screw propeller. Most of the ships in a modern powered fleet are screw vessels, including ordinary displacement vessels, submarines, and hydrofoils. Screw vessels may have one stern propeller (single-screw vessels) or several propellers (double-screw and triple-screw vessels); on some screw vessels (icebreakers and ferryboats) a propeller is also mounted in the bow section.