Hydrojet propulsion system

1 . A watercraft comprising:

a strut having a leading edge and a trailing edge;

a hydrofoil wing connected to the strut; and

a propulsion unit including a motor pod and a hydrojet unit, the motor pod including a front end portion attached to the strut and in-line with the leading and trailing edges of the strut and the hydrojet unit attached to a rear end portion of the motor pod, the propulsion unit operable to provide thrust, wherein a direction of thrust of the propulsion unit relative to the strut is adjustable.

2 . The watercraft of claim 1 wherein the hydrojet unit includes:

an inlet;

an outlet; and

a housing extending between the inlet and the outlet, the housing defining an interior that has a progressively decreasing cross-sectional dimension as the housing extends from the inlet toward the outlet.

3 . The watercraft of claim 2 wherein the front end portion of the motor pod is pivotably coupled to the strut.

4 . The watercraft of claim 1 further comprising a servo motor control mechanism operable to pivot the propulsion unit relative to the strut to change the direction of thrust of the hydrojet unit.

5 . The watercraft of claim 1 further comprising an attachment mechanism pivotably coupling the propulsion unit to the strut.

6 . The watercraft of claim 5 wherein the attachment mechanism includes a ball joint.

7 . The watercraft of claim 1 wherein the hydrojet unit is pivotable from a central position in all directions by about 20 degrees.

8 . The watercraft of claim 1 wherein the hydrojet unit is pivotable in a vertical direction, a horizontal direction, or a combination thereof.

9 . The watercraft of claim 1 further comprising a computing device configured to adjust a position of the hydrojet unit relative to the strut during operation of the watercraft.

10 . The watercraft of claim 9 wherein to adjust the position of the hydrojet unit includes adjusting a direction of thrust provided by the hydrojet unit to stabilize the watercraft.

11 . The watercraft of claim 9 wherein to adjust the position of the hydrojet unit includes adjusting a direction of thrust provided by the hydrojet unit to maintain a desired ride height.

12 . The watercraft of claim 1 further comprising a board connected to the strut.

13 . A watercraft comprising:

a flotation portion having an upper surface and a lower surface;

a strut extending from the lower surface of the flotation portion;

a motor pod including an electric motor disposed along the strut;

a hydrojet unit attached to the motor pod and to be driven by the electric motor to provide thrust, the hydrojet unit comprising:

an inlet;

an outlet;

a housing extending between the inlet and the outlet, the housing defining an interior that has a progressively decreasing cross-sectional dimension as the housing extends from the inlet toward the outlet; and

an impeller coupled to the electric motor and disposed in the housing; and

a computing device configured to:

operate the electric motor to cause the hydrojet unit to provide thrust; and

control a direction of thrust of the hydrojet unit.

14 . The watercraft of claim 13 further comprising a servo motor control mechanism in communication with the computing device, the servo motor control mechanism operable to pivot the direction of thrust of the hydrojet unit.

15 . The watercraft of claim 13 wherein to control a direction of the thrust of the hydrojet unit includes setting a position of the hydrojet unit relative to the strut.

16 . The watercraft of claim 13 wherein to control the direction of thrust includes adjusting a direction of thrust to stabilize the watercraft.

17 . The watercraft of claim 13 wherein to control the direction of thrust includes adjusting a direction of thrust to maintain a desired ride height.

18 . The watercraft of claim 13 wherein the motor pod has a first end portion pivotably coupled to the strut and a second end portion to which the hydrojet unit is attached.

19 . The watercraft of claim 13 further comprising an attachment mechanism pivotably coupling the hydrojet unit to the strut.

20 . The watercraft of claim 13 wherein the hydrojet unit is pivotable from a central position in all directions by about 20 degrees.

21 . The watercraft of claim 13 further comprising a hydrofoil wing mounted to the strut.

22 . The watercraft of claim 13 wherein the hydrojet unit includes:

an inlet portion comprising:

a substantially conical attachment interface attached to a rear portion of the motor pod; and

one or more fins extending outwardly from the attachment interface; and

the housing extending rearward of the inlet portion, the attachment interface intermediate the motor pod and the housing, the housing having an inlet region diameter greater than an outer diameter of the motor pod, the housing defining a fluid flow path from the inlet toward the outlet; and

a stator disposed within the housing rearward of the impeller.

23 . The watercraft of claim 1 wherein the hydrojet unit includes:

an inlet cross-section defined as an area of a space between an inner surface of a housing at an inlet region of the housing and an outer surface of an attachment interface, through which a fluid may flow into the hydrojet unit;

a low-pressure cross-section defined as an area of a space between the inner surface of the housing at an impeller region of the housing and an outer surface of a central hub of an impeller;

an outlet cross-section defined as an area of a space between the inner surface of the housing at an outlet region of the housing and an outer surface of a central hub of a stator disposed within the outlet region of the housing, through which the fluid may flow out of the hydrojet unit;

wherein the low-pressure cross-section is larger than the inlet cross-section;

and wherein the inlet cross-section is larger than the outlet cross-section.