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.

A jet propulsion watercraft includes a vessel body, a jet pump that is disposed at the vessel body and that includes a water jet opening, and a first guide that is attached to the vessel body. The jet pump generates a thrust by sucking in water existing around the vessel body and jetting the water from the water jet opening. The first guide receives water flowing on a lateral side of the vessel body and generates a downforce that generates a wake behind the vessel body.

A jet propulsion watercraft includes a vessel body, a jet pump that is disposed at the vessel body and that includes a water jet opening, and a first guide that is attached to the vessel body. The jet pump generates a thrust by sucking in water existing around the vessel body and jetting the water from the water jet opening. The first guide receives water flowing on a lateral side of the vessel body and generates a downforce that generates a wake behind the vessel body.

A boat includes a propulsion device and a surf device. The propulsion device is configured to move the boat in a forward direction through a body of water to generate a wake having a port-side wave and a starboard-side wave. The surf device includes an inlet, an impeller, and an outlet. The surf device is configured to draw water from the body of water through the inlet, accelerate the water by rotating the impeller, and discharge the accelerated water through the outlet to create a surfable wake.

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.

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.

A jet propulsion watercraft includes a vessel body, a jet pump that is disposed at the vessel body and that includes a water jet opening, and a first guide that is attached to the vessel body. The jet pump generates a thrust by sucking in water existing around the vessel body and jetting the water from the water jet opening. The first guide receives water flowing on a lateral side of the vessel body and generates a downforce that generates a wake behind the vessel body.

A jet propulsion watercraft includes a vessel body, a jet pump that is disposed at the vessel body and that includes a water jet opening, and a first guide that is attached to the vessel body. The jet pump generates a thrust by sucking in water existing around the vessel body and jetting the water from the water jet opening. The first guide receives water flowing on a lateral side of the vessel body and generates a downforce that generates a wake behind the vessel body.

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.

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.