Model of a Lifting Screw

Model of a screw casing between the sternpost and the rudderpost, with a section of the keel. The screw lifting device consists of a loose metal frame with a standard two-bladed screw, which can be raised and lowered in the casing by a rope running over a pulley at the top of the screw casing and a pulley in the screw frame. For this, the screw shaft must first be retracted. The screw frame moves over vertical rails against the sternpost and the rudderpost, which are provided with teeth; into these fall pallets of the screw frame that prevent it from sliding back. The pallets can be held back by pulling on two ropes, allowing the screw frame to descend. Clamping bars against the screw and sternpost can block the movement of the screw frame. The pin that prevents the screw from turning during lifting is missing. Scale 1:10 (derived).