GB488043A - Improvements in rudders for ships - Google Patents

Abstract

488,043. Rudders for ships. COLLIE, W. S. April 16, 1937, Nos. 10862 and 32677. [Class 114] A two-part rudder, of the kind in which there is a forward stationary part and movable after part, is constructed so that the forward part tapers aft symmetrically and that movement of the after part provides for a space between the two parts which continues to open, actually or in effect, and permits water to pass from the pressure side of the rudder to the suction side thereof. The fixed forward part 1 is formed as a streamline body, finishing aft beyond the pintle axis 3, whilst the movable part 2, also of streamline form, is carried by arms 4, so that the front edge is aft of the pintles and spaced from the part 1. In sequence, as the part 2 is moved relative to the part 1, there is a gap of increasing magnitude with the increasing angle. The forward edge of the fixed member 1 may be vertical or the upper and lower halves inclined to agree with the rake of the propeller blades, and the centre part may be enlarged at 5 to form a fairing for the propeller boss. Also, instead of the fixed part 1 being symmetrical it may be assymmetrical, and its shape reversed relatively above and below the propeller axis. Also, the main movable part may be slightly asymmetric to neutralize the flow from the single propeller. In another form, the stern of a ship may be extended to form or to carry the fixed part, and the movable part is then carried thereby. In other modifications, the movable part may be formed of a single plate or partly single plate and partly streamline section blade.