Abstract: A hydrodynamically balanced quiet control valve for a submarine (underwater ehicle) hovering system. The valve has a cylindrical valve element within a four-port valve housing. The interior of the valve element is divided into three chambers by a pair of parallel partitions extending lengthwise of the element and equally spaced from the element axis. Apertures in the cylindrical wall of the element are arranged, in cooperation with the partitions, to produce substantially constant total flow resistance through the valve when installed in the system, regardless of the angular rotation of the cylindrical valve element. A hover computer controls the angular position of the element in response to sensed pressure variations from the pressure at a preselected hovering depth.