Abstract: An apparatus for a ship's propeller, whose fins, which may be pitch-controlled, are provided in the vicinity of the leading edges with air openings. These air openings are fed via air ducts in each propeller fin by a compressed air source located in the ship. The compressed air is fed from the ship's compressor to the propeller by an air coupling which is protected by a split covering sleeve. The coupling is fed by an air feed line laid outside the ship's hull along the stern post or propeller strut. The air feed line penetrates the covering sleeve between the propeller strut and the propeller. The air line is connected to a two-piece inlet feed fitting. Air is fed from the inlet fitting through a two-piece bypass ring which rotates with the propeller shaft, to a two-piece air discharge fitting connected to the propeller hub.