Abstract: A self-adjusting propeller for sailing-boats comprises a propeller body mounted on a drivable rotary shaft and propeller blades rotatably mounted on the propeller body. These propeller blades are arranged, on movement of the boat in the water when the propeller is stationary, to assume a neutral position, while when the shaft is driven, they assume positions of rotation determined by stopping abutments for driving with the propeller. Each propeller blade is in this case so designed that the position line for the center of pressure along the propeller blade forms an arc from the shaft, the arc cutting the axis of rotation of the propeller blade a distance from the tip of the blade such that when the shaft is driven, the outer portion of the propeller blade provides a moment which counteracts the directed moment when the propeller is stationary.