A vessel with a retractable hydrofoil

Abstract

A rotatable and tiltable hydrofoil strut holding arrangement (3) for a hull (7) of a hydrofoil vessel (1) comprises a tiltable cage (37) mounted on at least one steering bearing (33, 81) attachable to the hull (7). The cage can surround a hydrofoil strut (5). Tilting of the cage and strut can be achieved without tilting of the steering bearing.

Description

[0001] A VESSEL WITH A RETRACTABLE HYDROFOIL

[0002] Technical field

[0003] The invention relates to a hydrofoil vessel comprising a hull, and a hydrofoil mounted to the hull by means of a tilting and rotating hydrofoil strut arrangement. The invention also relates to a tilting and rotating hydrofoil strut arrangement for mounting a hydrofoil to a hull of a vessel.

[0004] Background

[0005] Hydrofoil vessels can provide an energy efficient type of marine transportation. In order to achieve high efficiencies and comfort it is useful to be able to optimise the fore and aft trim of the vessel to take into account the prevailing sea conditions, weather conditions and the speed of the vessel. This trimming may require adjusting the angle of attack of the hydrofoils of the vessel , particularly the aft hydrofoil(s).

[0006] FR3082181AI relates to a watercraft strut holding device comprising a support element adapted to be linked to the hull of a watercraft, a cage (40) mounted to rotate relative to the support element around a main axis intended to be horizontal in use and transverse to the longitudinal direction of the watercraft - this can be used to tilt the strut. The cage has steering means for holding a strut which steering means is rotatable relative to the cage around a vertical secondary axis perpendicular to the main axis. As the steering means is part of the cage, tilting the cage requires tilting the steering means as well, which increases the moment of inertia of the cage and increases the force which needs to be overcome when tilting the cage.

[0007] Summary

[0008] An object of the invention is to provide a hydrofoil vessel in which the force required to tilt a strut can be reduced. This is achieved by a rotatable and tiltable hydrofoil strut holding arrangement according to claim 1 and a hydrofoil vessel according to claim 6.

[0009] Brief description of the invention

[0010] The tilting and rotating hydrofoil strut arrangement comprises a tiltable cage which can support a hydrofoil strut. Preferably the cage comprises lifting means for raising and lowering a strut in order to reduce the draft of the vessel when manoeuvring in shallow waters. The cage is itself supported by a bracket arrangement for supporting the cage which bracket arrangement is mounted on a rotatable bearing race of the two bearing races which together form one steering bearing for the cage. There may be more than one such steering bearing arranged in alignment and at a distance from each other. The bracket arrangement is arranged with a tilting arrangement with one or more pivots which allow the cage to pivot around a nominally horizontal axis. This horizontal axis may extend transverse the vessel when the steering is in the straight-ahead position. Pivoting of the cage about this axis causes a strut inside the cage to tilt. This tilting may be controlled by an actuator which connects the bracket arrangement or a rotatable bearing race to the cage and which actuator can cause the cage to tilt relative to the bracket arrangement or steering bearing race. Actuating the actuator in a first direction causes the cage and any strut within it to rotate in one direction around the pivots, thereby tilting the strut in that direction, while actuating the actuator in the opposite direction causes the strut to tilt in the opposite direction. The second bearing race of the steering bearing is attached to the vessel. Steering is achieved by rotating the first bearing race with respect to the second bearing race. This can be achieved by any suitable actuator means. For example, the first race can be the outer race of the steering bearing and this can be rotated by a rotatable belt arranged on the outer circumference of the outer race or a gear wheel or friction wheel acting on an exposed surface of the steering race. The first race could be the inner race of the bearing and the means for rotating it arranged accordingly. Steering can also be achieved by actuators arranged to directly rotate the first race, for example by moving a tiller arm attached to the first race. An advantage of this arrangement is that tilting of the strut does not cause any tilting of the steering bearing and this reduces the moment of inertia which is needed to be overcome when tilting the strut and simplifies the steering arrangement as the actuators do not need to be able to tilt.

[0011] Thus, the one or more steering bearings support a bracket arrangement which supports a tiltable cage which can support a strut.

[0012] In the following, the relative terms such as up, down, above, below, fore, aft, port, starboard, transverse, etc are related to when the invention is applied to a surface vessel with hull with a bow in the X-direction, a width with extends from port to starboard in the Y-direction and a height which extends from keel to superstructure in the Z direction. Similar reference numbers is different figures relate to the same feature.

[0013] Brief description of the figures

[0014] Figure 1 shows schematically a lateral view of a hydrofoil vessel with a tilting and rotating arrangement for tilting and steering at least one aft hydrofoil strut according to a first embodiment of the invention. Figures 2a) and 2b) show views from the side and in front of a tilting and rotating arrangement for a hydrofoil strut according to the first embodiment of the invention,

[0015] Figure 3 shows schematically a lateral view of a hydrofoil vessel with a tilting and rotating arrangement for tilting and steering at least one aft hydrofoil strut according to a second embodiment of the invention.

[0016] Figures 4a) and 4b) show views from the side and in front of a tilting and rotating arrangement for a hydrofoil strut according to the second embodiment of the invention.

[0017] Detailed description of the invention

[0018] Figure 1 shows a schematic lateral view from the starboard side of a hydrofoil vessel 1 comprising a tilting and rotating arrangement 3 for tilting and steering at least one aft hydrofoil strut 5 according to a first embodiment of the invention. The vessel has a hull 7 with bow 9 and a stern 11. In this example the vessel has at least one forward hydrofoil 13 mounted at or on the lower end 15 of a preferably retractable fore hydrofoil strut 17 which can be lowered to a cruising depth when the vessel is hydrofoiling and which strut can be retracted to reduce the draught of the vessel 1 when it is planing on its hull 7 , operating at displacement speeds or is moored. The vessel is provided by propulsion means such as a propellor, waterjet or, as illustrated here, a motor pod 19 at or on the lower end 21 of each, preferably retractable, aft hydrofoil strut 5. An aft hydrofoil 23 is also attached at or on the lower end 21 of each aft hydrofoil strut 5.

[0019] In order to allow the vessel to be steered and trimmed, it is usual to provide steering and trimming means for the vessel. In order to steer the vessel like a conventional vessel which uses one or more rudders, each aft hydrofoil strut is arranged to be able to be turned to port and starboard like a rudder. Fore and aft trimming can be achieved by tilting each aft hydrofoil strut fore or aft and, in the case of vessels with more than one aft hydrofoil strut, port and starboard trimming can be achieved by differential tilting of the aft hydrofoil struts.

[0020] Figure 2a) shows a schematic view from the port side of a tilting and rotating arrangement 3 for a steerable and tiltable hydrofoil. Figure 2b) shows a schematic view from the bow of a vessel with the arrangement of figure 2a). Steering is achieved by turning each aft hydrofoil strut 5 about a vertical or nearly vertical steering axis S and tilting of the strut is achieved by rotating each aft hydrofoil strut around a horizontal or nearly horizontal tilt axis T which extends transverse the vessel. The tilt axis (T) may be arranged so that it passes through said steering axis (S). Alternatively, the tilt axis (T) may be arranged so that it does not pass through said steering axis (S). Thus, steering can be achieved by rotating one of more aft hydrofoil struts to port or starboard and trimming of the vessel can be achieved by individually tilting each aft hydrofoil strut in the fore and aft direction. Such tilting changes the angle of attack of the aft hydrofoil and generates increased or decreased lift. In order to reduce the moment of inertia that needs to be overcome to tilt a hydrofoil the strut, tilting and rotating arrangement 3 is mounted on a bracket arrangement 29 to a rotatable, first race 31 of a steering bearing 33 which steering bearing comprises a second race 35 which is mounted to the hull 7 of the vessel. The tilting and rotating arrangement 3 comprises a cage 37 which surrounds the hydrofoil strut. Preferably the cage is provided with an actuator 39 for a hydrofoil strut lifting mechanism 41. Any suitable lifting mechanism can be used for this purpose, for example the actuator mechanism can comprise a toothed rack 43 mounted on the surface 45 of the hydrofoil strut and a cooperating gearwheel 47 which can be rotated by means of a rotary actuator, for example an electric or hydraulic motor 49. Lowering of the strut is achieved by rotating the gear wheel in a first direction and raising of the strut is achieved by rotating the gear wheel in the opposite direction. As the lifting mechanism is mounted on the cage it follows the steering and tilting movements of the cage and thus can lower or retract the hydrofoil strut independently of any angle that the cage may be tilted or rotated.

[0021] The bracket arrangement 29 of the tilting and rotating arrangement 3 comprises at least one, and preferably two, bracket(s) 51. Each bracket is connected to the cage by a tilt bearing arrangement 52 which comprises a substantially horizontal shaft 53 which extends from port to starboard of the vessel and which rotatably supports the cage by means of corresponding bearings 55 formed in or on the cage and / or in or on the bracket. The horizontal shaft forms the tilt axis T. The base of each bracket is firmly attached to the first race 31 of the steering bearing 33. Tilting is achieved by means of one of more tilt actuators 57. Each tilt actuator can be, for example, a linear actuator with a body 59 rotatably attached to pivot 61 on a bracket 51 and which linear actuator further comprises an extendable piston rod 63 which is pivotably attached at an exposed end 65 to a pivot 67 on the cage. Extending the extendable piston rod causes the cage to tilt around the tilt axis T in a first direction and retracting the piston rod causes the cage 37 to tilt around the tilt axis in the opposite direction.

[0022] This first race of the steering bearing to which the bracket arrangement 29 is attached, is provided with a steering mechanism 69. This can be any suitable system for rotating this first race. It may, for example, comprise a friction drive between the outer circumference 71 of the first race and a powered friction wheel 73 mounted on driving means (not shown), for example an electrical motor or hydraulic actuator, attached to the hull of the vessel. The gear wheel may be in direct contact with the outer circumference 71 of the first race or may drive the first race by means of a belt. The drive may be by way of friction or by toothed belt and toothed wheel or by gear wheel and corresponding teeth on the race or the like. Steering to port is achieved by rotating the outer race in a first direction and steering to starboard is achieved by rotating the outer race in the opposite direction.

[0023] The interior of the steering bearing is provided with a surface 77 to support the bracket arrangement 29 and this surface is provided with a through opening 79 which is wide enough and long enough to allow the hydrofoil strut to pass through it in order to be able to tilt fore and aft. Thus, the strut extends through the steering bearing. It is also conceivable that the cage also extends though the opening in the steering bearing.

[0024] In order to provide more rigidity to the tilting mechanism, it is conceivable to provide the strut holding arrangement with a second steering bearing 81 as shown by dotted lines in the figure 2a). This second steering bearing is arranged at a distance from, and concentric with, the first steering bearing 33. As shown by dotted lines, brackets 51'are extended so that they are connected to both the first and second bearings. Each bracket is provided with an opening 54 (in this example it is crescent shaped but can be of any suitable shape) through which the tilt actuators 57 can access the cage 37. One of the races of the second steering bearing is firmly attached to the hull of the vessel to provide stability and preferably the other, rotatable race is attached to the rotatable race of the first bearing so that they rotate together. In such an embodiment of the invention it is not necessary that both the cage 37 and the tilting actuator are attached to the same bracket arrangement 29 - the cage can be attached to a bracket on the rotating race of one of the steering bearings and the tilting actuator can be attached at one end to the cage and at the other end to a mounting means, such as a further bracket, on the rotating race of the other steering bearing.

[0025] In any embodiment of the invention the tilting actuator(s) can be in the form of a U-shaped saddle in which the ends of the arms of the U-shape are connected to two opposing sides of the cage and the base of the U-shape is attached to one of the rotating races of the steering bearing via a tilt actuator and, if necessary, a supporting bracket for the tilt actuator.

[0026] The invention has been illustrated by an embodiment in which the tilting and rotating arrangement is firmly attached to the hull by the fixed race of the steering bearing. This means that if a hydrofoil or hydrofoil strut strikes an obstacle then, if the impact force is high, the strut or hydrofoil will be damaged.

[0027] In order to reduce the risk of this happening, as shown in the second embodiment of the invention in figures 3 and figures 4a) and 4), it is possible to mount the strut holding arrangement to a mounting unit 101 which is able to rotate around a substantially horizontal, transverse axis C. In this arrangement an impact or other force acting on the hydrofoil or strut will produce a torque which will cause the mounting unit 101 to be rotated around the transverse axis and lift the hydrofoil and strut up and away from the source of the force. Preferably the mounting unit is biased or locked into the normal working position. This can be achieved by use of the weight of the mounting unit and tilting and rotating arrangement or by biasing or locking means 103. Biasing means may comprise resilient means such an elastomeric or metal spring, or a torsion bar arrangement or the like which prevents the mounting unit from moving until the weight or resilient or locking means forces which keep the mounting unit in the normal working position have been overcome. Locking of the mounting unit in position can be achieved using a locking arrangement such as a locking pin or locking bolt which is able to slide out of a locking position, or which is intentionally weakened, so that upon application of a predetermined torque or force it gives way or breaks and allows the mounting unit to rotate the hydrofoil and strut away from the impact / force acting on it.

Claims

CLAIMS1. A rotatable and tiltable hydrofoil strut holding arrangement (3) for a hull (7) of a hydrofoil vessel (1) comprising:- a cage (37) for holding a hydrofoil strut (5)- a first steering bearing (33) comprising a rotatable first race (31) connected to said cage in order to allow the cage to rotate around a steering axis (S) in relation to a second race (35) which second race is adapted to be attached to a hull (7) in order to provide a steering function to the cage (37),- characterized in that the cage (37) is tiltably supported by a bracket arrangement (29) which is fixed to the first race (31) of the first steering bearing (33), said cage and bracket arrangement comprising a tilt bearing arrangement (52) so that the cage (37) can be rotated in relation to the bracket arrangement (29) around a tilt axis (T) which is substantially perpendicular to the steering axis (S) wherein the steering bearing comprises a through opening (65) for a hydrofoil strut.

2. A strut holding arrangement (3) according to claim 1 characterized in that it comprises a second steering bearing concentric with the first bearing, wherein the second steering bearing comprises a rotatable first race which is fixed to the bracket arrangement, and a second race which is adapted to be attached to the hull (7)".

3. A strut holding arrangement according to claim 1 or claim 2 characterised in that the tilt axis (T) passes through said steering axis (S).

4. A strut holding arrangement according to claim 1 or claim 2 characterized in that the tilt axis (T) does not pass through said steering axis (S).

5. A strut holding arrangement according to any of the previous claims characterized in that said cage comprises a strut lifting mechanism (41) for raising and lowering a strut.

6. Hydrofoil vessel characterized in that it comprises a hydrofoil strut holding arrangement (3) according to any of claims 1-5.

7. Hydrofoil vessel according to claim 6 characterized in that the strut holding arrangement (3) is mounted to said vessel via a mounting unit (101) which is rotatably mounted around a substantially horizontal transverse axis (C).

8. Hydrofoil vessel according to claim 7 characterized that said mounting unit (101) is prevented from rotating around said transverse axis (C) by a biasing or locking mechanism (103) which prevents such rotation until a predetermined force has been applied to the biasing or locking mechanism in the direction of rotation.

9. Hydrofoil vessel according to any of claims 6 to 8 characterized in that it comprises a hydrofoil strut (5) which passes through the through opening (65).

Images