Abstract: An anchor windlass has a shaft on which an anchor-line sprocket is freely rotatable between an abutment fixed axially on the shaft and an entrainment emenet fixed rotationally but axially shiftable on this shaft. A nut threaded on the shaft bears via a stack of spring washers on this entrainment element and can be screwed axially forwardly on the shaft to wedge the sprocket between the entrainment element and the abutment to rotationally couple the sprocket to the shaft, and can be screwed axially backwardly on the shaft to allow free rotation of this sprocket on the shaft. A pawl and cam mechanism serves to automatically rotationally temporarily arrest the nut to screw it in the desired direction for coupling the sprocket to the shaft or uncoupling it therefrom.