Abstract: Hydraulic jet propulsion apparatus having steering deflectors which are hydraulically balanced which operate against a seal to reduce spillage and to reduce jamming ans which will provide a smooth contour for the flow of water while not restricting the cross-sectional area of the jet stream. The apparatus also provides a reversing duct which is operable to intercept the jetstream, downstream of the steering deflectors so that the jetstream is divided into two streams the relative proportions of which depend upon the operation of the steering means each stream being turned while in the duct through an angle in excess of 90 degrees to emerge in diagonal directions respectively forward-to-port and forward-to-starboard so as to produce a reverse thrust with steering dependant on the relative proportions of flow in the two streams.