One embodiment of the invention comprises a method for controlling a marine vessel having a first steerable propulsor, a corresponding first reversing device, a second steerable propulsor and a corresponding second reversing device. The method comprises receiving a first vessel control signal corresponding to a rotational movement and no translational movement command, generating at least a first actuator control signal and a second actuator control signal in response to the first vessel control signal, coupling the first actuator control signal to and controlling the first steerable propulsor and the second steerable propulsor, and coupling the second actuator control signal to and controlling the first reversing device and to the second reversing device. The method creates rotational forces on the marine vessel with substantially no translational forces on the marine vessel.

One embodiment of the invention comprises a method for controlling a marine vessel having a first steerable propulsor, a corresponding first reversing device, a second steerable propulsor and a corresponding second reversing device. The method comprises receiving a first vessel control signal corresponding to a rotational movement and no translational movement command, generating at least a first actuator control signal and a second actuator control signal in response to the first vessel control signal, coupling the first actuator control signal to and controlling the first steerable propulsor and the second steerable propulsor, and coupling the second actuator control signal to and controlling the first reversing device and to the second reversing device. The method creates rotational forces on the marine vessel with substantially no translational forces on the marine vessel.

Described is a robot (1) for cleaning swimming pools comprising a main body (2), a plurality of rotors (3), a control unit and means for cleaning the swimming pool. The main body (2) has at least one sealed containment space (4). The plurality of rotors (3) is configured for generating a hydrodynamic thrust designed for moving the robot inside an entire space of the swimming pool. The control unit inserted in the containment space (4) and is configured for modifying at least one respective operating parameter of each rotor (3) in such a way as to direct the hydrodynamic thrust.

Described is a robot (1) for cleaning swimming pools comprising a main body (2), a plurality of rotors (3), a control unit and means for cleaning the swimming pool. The main body (2) has at least one sealed containment space (4). The plurality of rotors (3) is configured for generating a hydrodynamic thrust designed for moving the robot inside an entire space of the swimming pool. The control unit inserted in the containment space (4) and is configured for modifying at least one respective operating parameter of each rotor (3) in such a way as to direct the hydrodynamic thrust.

A method for reducing the swinging of a ship anchored or moored to a buoy, by the suitable activation of the bow thruster and the stern thruster of the ship in accordance with the signals obtained by at least one of the following sensors: a) gyroscope, b) magnetometer, c) anemometer, d) GPS, e) inertial navigation system, f) a device measuring the angle between the longitudinal axis of the ship and the vertical plane through the anchor chain of the ship, is described.

A method for reducing the swinging of a ship anchored or moored to a buoy, by the suitable activation of the bow thruster and the stern thruster of the ship in accordance with the signals obtained by at least one of the following sensors: a) gyroscope, b) magnetometer, c) anemometer, d) GPS, e) inertial navigation system, f) a device measuring the angle between the longitudinal axis of the ship and the vertical plane through the anchor chain of the ship, is described.

A jet propulsion watercraft includes a vessel body, an engine, a jet propulsion unit, a weight information obtaining processor, an engine controller, and a target rotational speed determining processor. The engine is accommodated in the vessel body. The jet propulsion unit is driven by the engine and propels the vessel body. The weight information obtaining processor obtains weight information regarding a weight of the vessel body. The engine controller controls an engine rotational speed such that a vessel velocity reaches a predetermined set velocity. The target rotational speed determining processor determines a target engine rotational speed corresponding to the set velocity in accordance with the weight information. The engine controller controls the engine rotational speed such that the vessel velocity reaches the set velocity based on the target engine rotational speed determined in accordance with the weight information.

A jet propulsion watercraft includes a vessel body, an engine, a jet propulsion unit, a weight information obtaining processor, an engine controller, and a target rotational speed determining processor. The engine is accommodated in the vessel body. The jet propulsion unit is driven by the engine and propels the vessel body. The weight information obtaining processor obtains weight information regarding a weight of the vessel body. The engine controller controls an engine rotational speed such that a vessel velocity reaches a predetermined set velocity. The target rotational speed determining processor determines a target engine rotational speed corresponding to the set velocity in accordance with the weight information. The engine controller controls the engine rotational speed such that the vessel velocity reaches the set velocity based on the target engine rotational speed determined in accordance with the weight information.

A watercraft propulsion system is disclosed for an amphibious vessels. The watercraft propulsion system includes a waterjet on each side of the vessel which consist mainly of an impeller, inlet assembly, and stator assembly. The waterjets resists vibrational fatigue and failure through specialized welding between the struts and the inside of the conduit of the inlet assembly. The waterjets can be retrofitted to existing drive shafts to meet the performance requirements of differing amphibious and other marine vessels and to accommodate space limitations. The waterjets are easily installed and removed.

A watercraft propulsion system is disclosed for an amphibious vessels. The watercraft propulsion system includes a waterjet on each side of the vessel which consist mainly of an impeller, inlet assembly, and stator assembly. The waterjets resists vibrational fatigue and failure through specialized welding between the struts and the inside of the conduit of the inlet assembly. The waterjets can be retrofitted to existing drive shafts to meet the performance requirements of differing amphibious and other marine vessels and to accommodate space limitations. The waterjets are easily installed and removed.