Powerboat
A powerboat comprising a hull, a plurality of dynamically adjustable hydrofoils positioned below the waterline towards the rear of the hull, and a control system, wherein the cross sectional area of the hull below the waterline decreases towards the rear of the hull, and the control system is configured to adjust the hydrofoils in operation of the powerboat to control the running trim of the powerboat. The powerboat can operate efficiently at over a wide range of Froude numbers, in particular both low (displacement mode) speeds and high (planing mode) speeds.
1. A powerboat comprising:
a hull;
a plurality of dynamically adjustable hydrofoils positioned below the water line towards the rear of the hull; and
a control system;
wherein the cross-sectional area of the hull below the waterline decreases towards the rear of the hull; and
the control system is configured to adjust the hydrofoils in operation of the powerboat to control the running trim of the powerboat; and
wherein the hydrofoils are configured to support between 0% and 50% of the weight of the powerboat at its top speed.
2. The powerboat according to claim 1 , wherein the hydrofoils are at least one of retractable and movable to a position above the waterline.
3. The powerboat according to claim 2 , wherein the hydrofoils are retractable into a recess in the hull.
4. The powerboat according to claim 1 , wherein the hydrofoils further comprise a trailing edge flap.
5. The powerboat according to claim 1 , further comprising a fixed hydrofoil.
6. The powerboat according to claim 5 , wherein the centerline of the fixed hydrofoil is substantially aligned with the centerline of the powerboat.
7. The powerboat according to claim 1 wherein the hydrofoils are positioned aft of the powerboat drive.
8. The powerboat according to claim 1 wherein the hydrofoils are positioned forwards of the powerboat drive.
9. The powerboat according to claim 1 wherein the hydrofoils are positioned both forwards of and aft of the powerboat drive.
10. The powerboat according to claim 1 wherein the hydrofoils are configured to support between 10% and 40% of the weight of the powerboat at top speed.
11. The powerboat according to claim 1 wherein the hydrofoils are configured to support between 15% and 25% of the weight of the powerboat at top speed.
12. The powerboat according to claim 1 wherein the control system is configured to automatically adjust the hydrofoils to at least one of:
control the running trim of the powerboat;
control at least one of roll and pitch motions of the boat; and
reduce and minimize hydrodynamic drag on the hull.
13. The powerboat according to claim 1 wherein the immersed area of the transom at rest is less than 40% of the maximum hull cross-sectional area.
14. The powerboat according to claim 1 wherein the controller comprises a speed sensor and/or attitude sensor.
15. The powerboat according to claim 1 wherein the hydrofoils are positioned in the rear 30% of the length of the hull.
16. The powerboat according to claim 1 wherein each hydrofoil is connected to the hull by one or more struts.
17. The powerboat according to claim 1 wherein a strut connecting the hydrofoil to the hull is used as a rudder.
18. The powerboat according to claim 1 wherein all portions of the bow which are below the design waterline are in line with, or aft of, all portions of the bow which are above the design waterline.
19. The powerboat according to claim 1 wherein the stem of the powerboat is substantially vertical.
20. The powerboat according to claim 1 wherein the longitudinal position of maximum width of the hull is at 70% or less of the distance from bow to stern.
21. The powerboat according to claim 1 wherein a transition from V-shaped hull underwater cross section at the bow to rounded underwater hull cross section occurs by 50% of the distance from bow to stern.