Abstract: Device which is independent of the main propulsion system of a ship, and which can be used selectively as a passive rudder or as an active maneuvering mechanism, and consists of one or more blades, a wheel body, a transmission and one or more control units.When the wheel body is stationary, in response to commands from the control unit or units, the blades can be oriented separately by means of the transmission and can be coupled or uncoupled to set the required angle with respect to the longitudinal axis of the ship. In that case, the device acts as a passive rudder.When the wheel body is rotating, the position of the eccentrically located blade or blades is varied during a rotation of the wheel body so that a resulting thrust is generated on account of the hydrodynamic forces which act on the blade or blades. The direction of the thrust can be set in any desired direction by means of the control unit or control units and the sun wheel or the sun wheels of the transmission.

Abstract: A process for detecting a phase boundary surface between layers of fluids which are not intermixable with one another includes the steps of penetrating at least one of the fluids with sound waves to strike a reflector, receiving the reflected sound waves, comparing the transmitted sound waves to the reflected and received sound waves, using the comparison to determine the acoustic propagation impedance, and using the results to determine the position of the phase boundary layer.