Control of multi-hulled vessels

1. A vessel having a body portion that is at least partially suspended above at least one left moveable hull and at least one right moveable hull, each moveable hull being moveable with respect to the body portion, at least one sensor arranged to sense at least one operational parameter of the vessel, and a controller configured to control a roll attitude of the body portion by causing the orientation of the body portion of the vessel relative to the hulls to change,

the roll attitude of the body portion being adjustable and controlled during operation in response to said at least one operational parameter to ensure that the sum of the gravitational force and the centrifugal force acting on the vessel during a turn has a line of action that is substantially perpendicular to a deck of the vessel,

wherein the at least one operational parameter includes at least one lateral acceleration parameter.

2. A vessel as claimed in claim 1 wherein the at least one lateral acceleration parameter includes a predicted lateral acceleration, being a function of steering angle and speed.

3. A vessel as claimed in claim 1 wherein the at least one lateral acceleration parameter includes a calculated lateral acceleration, being a function of steering angle and speed.

4. A vessel as claimed in claim 1 wherein the at least one lateral acceleration parameter includes a calculated lateral acceleration, being a function of suspension support forces.

5. A vessel as claimed in claim 1 wherein the at least one lateral acceleration parameter includes a measured lateral acceleration, being measured in a lateral direction oriented horizontally with respect to the body portion.

6. A vessel as claimed in claim 1 wherein the at least one lateral acceleration parameter includes a measured lateral acceleration, being measured in a lateral direction relative to ground.

7. A vessel as claimed in claim 1 wherein the body portion is entirely supported above said at least one left moveable hull and at least one right moveable hull.

8. A vessel as claimed in claim 1 wherein the body portion of vessel additionally includes at least one fixed hull, fixed to the body portion and providing partial support of the body portion relative to the water surface.

9. A vessel as claimed in claim 1 wherein the at least one left moveable hull is a single hull disposed at a left side of the vessel and the at least one right moveable hull is a single hull disposed at a right side of the vessel.

10. A vessel as claimed in claim 1 wherein the at least one left moveable hull includes a forward left hull and a rearward left hull and

the at least one right moveable hull includes a forward right hull and a rearward right hull.

11. A vessel as claimed in claim 1 wherein the body is entirely suspended above said at least two hulls which are individually moveable relative to the body in a vertical direction, but constrained from moving in a lateral direction oriented horizontally relative to the body,

the balance of load between each hull being substantially maintained during a coordinated turn.

12. A vessel as claimed in claim 1 wherein the control of the roll attitude of the body portion includes time or wherein the at least one operational parameter is time-averaged.

13. A vessel as claimed in claim 1 wherein the body portion is supported above the hulls by a suspension system including multiple support devices, the control of the roll attitude of the body portion using pressures within at least one of said multiple support devices.

14. A vessel as claimed in claim 1 wherein the body portion is supported above the hulls by a suspension system including multiple support devices, the roll attitude of the body portion being controlled up to a roll attitude limit which is determined in dependence on at least one support device exceeding a predefined travel limit.

15. A vessel as claimed in claim 1 wherein the roll attitude of the body portion is controlled up to a roll attitude limit which is determined in dependence on hull displacement relative to the body portion and/or a detected sea state.

16. A vessel as claimed in claim 1 wherein the body portion is supported above the hulls by a suspension system including multiple support devices, the control of the roll attitude of the body portion using loads upon at least one of said multiple support devices.

17. A vessel as claimed in claim 1 wherein the body portion is supported above the hulls by a suspension system including multiple support devices, the roll attitude of the body portion being controlled up to a roll attitude limit which is determined in dependence on at least one support device exceeding a predefined pressure or load.

18. A vessel as claimed in claim 1 wherein the roll attitude of the body portion is controlled up to a roll attitude limit which is determined in dependence on a detected sea state.

19. A method of controlling the roll angle of a body portion of a vessel, the vessel further including at least two hulls moveable relative to the body portion, the body portion being at least partially supported above said at least two hulls,

the method including the steps of detecting at least one lateral acceleration parameter and controlling a roll angle of the body portion relative to the movable hulls by causing the orientation of the body portion of the vessel relative to the hulls to change using the at least one lateral acceleration parameter to ensure that the line of action of the sum of the gravitational force and the centrifugal force acting on the vessel during a turn is substantially perpendicular to a deck of the vessel.

20. A method according to claim 19 wherein the step of detecting the lateral acceleration of the body portion uses at least one lateral accelerometer mounted to the body portion.

21. A method according to claim 19 wherein the step of detecting at least one lateral acceleration parameter includes the steps of measuring vessel operating parameters and calculating or predicting turning forces on the body portion.

22. A method according to claim 21 wherein the operating parameters include vessel speed & steering angle.

23. A method according the claim 19 wherein the step of adjusting the roll angle of the body using the at least one lateral acceleration parameter includes the step of adjusting the roll angle of the body to ensure that at least a vertical component of the pressure loads on the at least one left hull is within 15% of the equivalent at least vertical component of the pressure loads on the at least one right hull.

24. A method according to claim 23 wherein the vessel further includes a suspension system for supporting at least a portion of the body above or relative to the at least one left hull and one right hull,

the method further including the step of estimating or measuring at least one load on or at least one pressure in the suspension system.

25. A method according to claim 19 further including the steps of:

determining the leeway angle with which the vessel is proceeding; and

calculating a roll angle offset to reduce or remove any difference between a roll angle set point for a perfectly coordinated turn and a roll angle set point calculated using inputs influenced by the leeway angle.

26. A method according to claim 25 wherein the magnitude of the roll angle offset is decayed over time.

27. A method according to claim 19 further including the steps of:

determining a magnitude of payload offset; and

calculating a roll angle offset to reduce or remove any difference between a roll angle set point for a perfectly coordinated turn and a roll angle set point calculated using inputs influenced by the magnitude of payload offset.

28. A method according to claim 27 wherein the magnitude of the roll angle offset is decayed with time.