A system for controlling a marine vessel having first and second waterjets, corresponding first and second steering nozzles and corresponding first and second reversing buckets. The system comprises a speed control device for providing a first vessel control signal that corresponds to a speed to be provided to the marine vessel, a processor configured to receive the first vessel control signal and that is configured to provide at least one first actuator control signal coupled to the first and second waterjets, and at least one second actuator control signal coupled to the first and second steering nozzles and the first and second reversing buckets. The system any of improves upon turns provided by conventional waterjet propulsion systems, improves upon slowing down or stopping marine vessels as is done by conventional waterjet propulsion systems, and improves upon the controllability of the waterjet propulsed marine vessel at low vessel speeds.

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.

A watercraft includes a hull, a wave detector to detect wave conditions on a water surface, a trim adjuster to adjust a trim angle of the watercraft, and a controller. The controller is configured or programmed to determine, based on a detection value of the wave detector, whether or not the water surface is smooth and, if it is determined that the water surface is not smooth, control the trim adjuster to increase the trim angle.

A watercraft includes a hull, an engine to generate power to propel the hull, an engine speed sensor to detect the rotation speed of the engine, and an ON/OFF sensor to be turned on and off according to a vertical acceleration of the hull. The watercraft further includes a controller configured or programmed to determine, based on at least one of a detection value of the ON/OFF sensor and a detection value of the engine speed sensor, whether or not a water surface is smooth.

The invention relates to a method for controlling a water jet propulsion device for the propulsion of a marine vessel, the water jet propulsion device comprising: a conduit extending between an inlet and an outlet; an impeller in the conduit; and a mechanical power provider arranged to deliver power to the impeller; the method comprising receiving a plurality of thrust commands, and controlling a thrust level of the water jet propulsion device in dependence the thrust commands, wherein controlling the thrust level comprises adjusting a position of a deflector arranged to deflect water flowing out of the outlet, characterised by coordinating the adjustment of the position of the deflector with a level of engagement of a clutch, arranged to adjust the delivery of power from the power provider to the impeller, so that the thrust level is substantially continuous in a thrust command domain.

Provided is a rudder assembly producing significant thrust to reduce energy consumption of vessels during voyage. The rudder assembly is formed of first/second rudder units arranged on both sides of first/second propellers. As seen from rear, each first/second rudder unit is formed of left/right rudders arranged on the left/right of the first/second propeller. Each left/right rudder of the first/second rudder units is formed of a first left/right rudder portion extending in the right-left direction, a second left/right rudder portion curved from the left/right end of the first left/right rudder portion toward lower left/right, and a third left/right rudder portion extending downwards from the lower end of the second left/right rudder portion. The first left/right rudder portions of the first/second rudder unit are arranged spaced upwardly apart from the upper edge of the tip circle of the first/second propeller for a distance of 10-20% of the diameter of the first/second propeller.

Provided is a rudder assembly producing significant thrust to reduce energy consumption of vessels during voyage. The rudder assembly is formed of first/second rudder units arranged on both sides of first/second propellers. As seen from rear, each first/second rudder unit is formed of left/right rudders arranged on the left/right of the first/second propeller. Each left/right rudder of the first/second rudder units is formed of a first left/right rudder portion extending in the right-left direction, a second left/right rudder portion curved from the left/right end of the first left/right rudder portion toward lower left/right, and a third left/right rudder portion extending downwards from the lower end of the second left/right rudder portion. The first left/right rudder portions of the first/second rudder unit are arranged spaced upwardly apart from the upper edge of the tip circle of the first/second propeller for a distance of 10-20% of the diameter of the first/second propeller.

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.