NL2011490C2

NL2011490C2 - Kite powered vessel having a movable keel.

Info

Publication number: NL2011490C2
Application number: NL2011490A
Authority: NL
Inventors: Hilbrand Leemans
Original assignee: Hilbrand Leemans
Priority date: 2013-09-23
Filing date: 2013-09-23
Publication date: 2015-03-24
Also published as: EP2851279A1

Abstract

The present invention relates to a kite-powered vessel (10), comprising: - a deck (12), and - a keel (14), wherein the keel is connected to the deck via at least one rotary mechanism (30), wherein when seen in front view the keel is rotatable relative to the deck between a left position and a right position about a longitudinal axis (5) and along a path (16) which has a shape of an arc (27) of a circle (29), wherein the longitudinal axis (5) is a center (18) of said circle and is located at a distance (28) from the keel.

Description

Title: Kite powered vessel having a movable keel

Field of the invention and prior art

The present invention relates to a kite powered vessel. Kite powered vessels are known. A kite powered vessel is disclosed in W02005/100149.

The invention

In the present invention, it was recognized that kite powered vessels have a poor performance when going to windward. Also, it was recognized that kite-powered vessels are light and can easily be (partly) pulled out of the water when the force on the kite increases.

In order to solve at least one of these problems, the invention provides a kite-powered vessel, comprising: - a deck, - a keel, wherein the keel is connected to the deck via at least one rotary mechanism, wherein when seen in front view of the vessel the keel is rotatable relative to the deck between a left position and a right position about a longitudinal axis and along a path which has a shape of an arc of a circle, wherein the longitudinal axis is a center of said circle and is located at a distance from the keel, wherein the keel has a first primary surface and a second primary surface which are located on opposite sides of the keel, wherein the first primary surface faces the center in both the left and right position.

The present invention allows the keel to be positioned directly opposite to the pulling force of the kite. In other words, the force of the water on the keel opposes the forces of the kite on the vessel.

In an embodiment, when the vessel is in a horizontal orientation, the keel is inclined in both the left and right position when seen in front view of the vessel, wherein the first primary surface faces upwards in both the left and right position, and wherein the second primary surface faces downwards in both the left and right position.

In an embodiment, the first primary surface is concave and the opposite second primary surface is convex, and the concave surface of the keel faces the center. The concave side of the keel faces the center of the circle of which the path forms a part.

In an embodiment, a body of water (a volume) is wedged between the primary surface which faces the center and a hull of the vessel.

The volume may be defined between the concave side and the hull of the vessel. In use, the body of water which is present in said volume stabilizes the vessel. When a wind gush exerts an upward force on the vessel, the volume of water prevents the vessel from being lifted upwards.

This allows the vessel according to the invention to have a stable behaviour. It also allows a high power to weight ratio. In other words, a rather large kite can be used relative to the vessel, because said body of water stabilizes the vessel.

The high power to weight ratio allows the vessel to be used as a tug boat to tow other vessels or other objects. The vessel may also be used to tow fishing nets or other materials which are under water.

The said body of water forms ballast which is outside the vessel. Normally, ballast tanks are provided inside the vessel, which leads to a large and heavy vessel. In the present invention, ballast is created which is outside the vessel. This obviates the need for a large vessel. Hence, the vessel itself can stay relatively small. Or in other words, a relatively large kite can be used.

The vessel in particular has good upwind behaviour. In many kite powered boats, going upwind is difficult, because the large lateral force of the wind pulls the vessel out of the water. In the present invention, the water force on the keel counteracts the lateral force of the wind and keeps the boat in the water.

In use, the keel exerts a force on the vessel comprising a lateral component and a downward component.

In an embodiment: in the left position a first section of the keel forms an upper part of the keel and a second section of the keel forms a lower part of the keel, and in the right position the first section of the keel forms the lower part of the keel and the second section of the keel forms the upper part of the keel.

In an embodiment, when seen in front view, the keel is not straight, and is preferably substantially arc-shaped.

In an embodiment, when seen in front view, at least a part of said keel extends along said arc-shaped path. In particular substantially the entire keel may extend along said arcshaped path, when seen in front view.

In an embodiment, the center of the circle is located at a distance from the keel.

In an embodiment, the keel is connected to the hull via at least one rotary mechanism

In an embodiment, the keel is constructed and arranged to be in rotational equilibrium about the longitudinal axis.

Generally, the rotary mechanism comprises a stationary part and a rotary part, wherein the keel is fixed to the rotary part.

In an embodiment, the rotary mechanism comprises: - at least one rail, the rail being stationary relative to the deck, and a slider which is moveably arranged on said rail, wherein when seen in front view the rail and the slider have an arc-shape, and wherein the keel is mounted to said slider, or - a rotary axle, wherein the keel is connected to said axle via one or more spokes.

The arc-shaped element may be a wheel. The rail may be fixed to the deck directly or indirectly.

In an embodiment, the keel is connected to the hull via at least one rotary mechanism which comprises a rail and a slider, and wherein when seen in front view the rail forms an arc.

In an embodiment, the vessel comprises at least one line mount for connecting a kite line to the vessel, wherein the at least one line mount is fixed to the rotary part of the rotary mechanism

The line mount may be connected to the slider or to a rotary element connecting the keel with the spokes.

In an embodiment, the vessel comprises two rotary mechanisms, one rotary mechanism being positioned relatively forward and one rotary mechanism being positioned relatively to the rear of the vessel, wherein the keel is connected to both rotary mechanisms.

In an embodiment, the vessel comprises a circular rotary mechanism, wherein the rail defines a full circle, and in particular comprising a circular rotary mechanism at the front of the vessel and a circular rotary mechanism at the rear of the vessel.

In an embodiment, in front view the at least one rotary mechanism defines an opening below the deck, wherein the opening is configured to allow a flow of water through said opening when the vessel moves forward.

In an embodiment, the vessel comprises two rotary mechanisms, and wherein each rotary mechanism comprises a left water piercing part and a right water piercing part which pierce the water surface and provide stability to the vessel.

In an embodiment, each rotary mechanism comprises two arc-shaped rails, one left rail which is positioned on the left side of the vessel and one right rail which is positioned on the right side of the vessel.

In an embodiment, the vessel comprises a single rotary mechanism.

In an embodiment, the vessel comprises two parallel hulls and an interconnecting deck.

In an embodiment, the at least one rotary mechanism is connected to the deck via a tilting mechanism configured for tilting the rotary mechanism relative to the deck, thereby adjusting a pitch angle of the keel.

In an embodiment, the keel extends over a horizontal distance and over a vertical distance and wherein the horizontal distance is more than twice the vertical distance.

In an embodiment, the keel is symmetrical about a longitudinal plane extending through the center of the circular path and through a center of the keel.

The present invention further relates to a method of sailing, comprising: - providing the kite-powered vessel according to the invention, and - pulling the vessel with a kite, wherein the water exerts a force (F1) on the keel which is substantially opposite to a force (F2) exerted by the kite on the vessel.

In an embodiment of the method, the method comprises: - positioning the kite on the starboard side of the vessel and positioning the keel on the port side, - tacking or jibing the vessel, thereby moving the kite from the starboard side to the port side and rotating the keel along the circular path from the port side to the starboard side.

One of the advantages of the present vessel may be that the overturning moments are lower than in other kite powered vessels. When the kite is on starboard and the keel is on port, the force of the kite is counteracted by the force of the keel (or rather the force of the water on the keel). The keel therefore provides a stabilizing force.

Further, the water which is located above the keel has a certain mass, i.e. inertia. In case of a wind gust, the force of the kite may increase quite dramatically. The water above the keel prevents the vessel from being lifted by the wind force. This provides improved dynamic behaviour to the vessel.

List of figures

Embodiments of the feeder device according to the invention will be described by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

Figure 1 shows an isometric view of an embodiment of the invention.

Figure 2 shows a top view of the embodiment of figure 1.

Figure 3 shows a side view of another embodiment of the invention.

Figure 4 shows a cross-section along the line A - A shown in figure 3.

Figure 5 shows a cross-section along the line B - B shown in figure 3.

Figure 6 shows a front view of the embodiment of figure 1 with different positions of the keel.

Figure 7 shows a front view of the embodiment of figure 1 with the kite lines.

Figure 8 shows a front view of the embodiment of figure 1 with different kite line mounts.

Figure 9 shows an isometric view of another embodiment of the invention.

Figure 10 shows a cross section of an embodiment of a rotary mechanism of the embodiment of figures 1-8 and the embodiment of figure 9.

Figure 11 shows a cross section of another embodiment of the rotary mechanism of the embodiment of figures 1-8 and the embodiment of figure 9.

Figure 12 shows a top view of another embodiment of the invention.

Figure 13 shows a side view of the embodiment of figure 12.

Figure 14 shows an isometric view of the embodiment of figure 12.

Figure 15 shows a cross-section of a rotary mechanism in the embodiment of figures 12-14

Figure 14 shows a cross-section of another embodiment of a rotary mechanism in the embodiment of figures 12-14.

Figure 17 shows an isometric view of another embodiment.

Figure 18 shows a side view of the embodiment of figure 17.

Figure 19 shows a front view of the embodiment of figure 17.

Figure 20 shows a side view of another embodiment.

Figure 21 shows a front view of the embodiment of figure 20.

Figure 22 shows a side view of another embodiment.

Figure 23 shows a top view of the embodiment of figure 22.

Figure 24 shows a front view of the embodiment of figure 22.

Detailed description of the figures

Turning to figures 1 - 2, a first embodiment of the kite powered vessel 10 according to the invention is shown. The vessel 10 comprises a deck 12 and a keel 14. The water line is indicated with reference numeral 90. The vessel comprises buoyancy compartments 42 which form two hulls 46, a left hull 46 and a right hull 46. The buoyancy compartments 42 are positioned below the deck. The buoyancy compartments extend lengthwise of the vessel.

The keel 14 is connected to the hull via at least one rotary mechanism 30. The rotary mechanism comprises a stationary part 6 and a rotary part 7. The stationary part is stationary relative to the deck. The keel is fixed to the rotary part 7.

In the embodiment of figures 1 - 2, the vessel comprises two rotary mechanisms 30A, 30B. One rotary mechanism 30A is positioned relatively forward on the vessel. One rotary mechanism 30B is positioned relatively to the rear of the vessel. The keel is connected to both rotary mechanisms. The keel extends longitudinally between both rotary mechanisms 30A, 30B.

Each rotary mechanism 30 comprises two fixed rails 32. The fixed rails 32 are provided at the forward ends of hulls 46. One rail 32 is provided at the forward end of the left hull and one rail 32 is provided at the forward end of the right hull 46.

In front view, the rails 32 form an arc, more particular a circle. The slider slides along the rail. The slider 34 is also circular. The rotary part 7 of the rotary mechanism has a circular shape and forms a circular slider 34 which slides along both rails 32. The keel is fixed to the rotary part 7. A same construction is present at the rear of the vessel, where a rotary part 7 forms a slider 34 which slides along rails 32 to make a rotary movement.

Turning to figures 3 - 6, an embodiment is shown which is similar to the embodiment of figures 1 and 2 in most aspect. The rails 32 are also arc-shaped but do not form a full circle. The rails substantially 32 have the form of a half-circle.

When seen in front view, the keel 14 is rotatable relative to the hull along a path 16. The path 16 has a shape of an arc 27 of a circle 29. The keel is rotatable between a left position and a right position. The arc-shaped path along which the keel travels may not be a full circle, but only a part of the circle 29. The arc shaped path 16 follows the circumference of the circle 29.

When seen in front view, at least a part of said keel is curved and may extend along said arc-shaped path 16. The keel 14 itself therefore may be arc-shaped. In front view, the curved shape of the keel does not necessarily have the same curvature as the path 16, but for instance may be slightly less curved. A concave side of the keel faces a center 18 of the circle 29 of which the path 16 forms a part. The center 18 defines the longitudinal axis 5 about which the keel rotates.

The keel 14 is mounted to rotate between a left position 20 and a right position 22, see figure 6. The keel may also adopt any position in between the left and right position, such as a central position 21.

In the left position 20, a first section 24 of the keel forms an upper part of the keel and a second section 26 of the keel forms a lower part of the keel, and in the right position 22 the first section 24 of the keel forms the lower part of the keel and the second section 26 of the keel forms the upper part of the keel.

The center 18 of the circle is located at a distance 28 from the keel. The entire keel is positioned at a distance from the center 18.

The keel 14 extends over a horizontal distance 100 and over a vertical distance 102. The horizontal distance is more than twice the vertical distance.

Turning to figure 6, the keel 14 is symmetrical about a longitudinal plane 17 which extends through the center 18 of the arc-shaped or circular path 16 and through a center 19 of the keel. The skilled person will understand that the longitudinal plane may not be vertical but may be inclined when the keel is positioned

Turning to figure 4, the keel comprises a first primary surface 35 and a second primary surface 36. The first primary surface 35 faces the center 18 in the left position and in the right position.

The first primary surface is concave, and the second primary surface is convex. The surfaces may also be hooked when seen in front view.

When the vessel is horizontal, both surfaces 35 and 36 are inclined when seen in front view. The first primary surface 35 faces upward and the second primary surface 36 faces downward, at least when the vessel is horizontal.

The keel 14 is constructed and arranged to be in rotational balance about the longitudinal axis 5. In other words, the resulting force on the keel travels though the center 18 or substantially through said center. In use, the keel 14 therefore does not have a tendency to rotate as a result of the water forces on the keel. in front view the rotary mechanisms define an opening 40 below the deck 12. The opening is configured to allow a flow of water through said opening when the vessel moves forward. Furthermore in use a body 41 of water is located between the keel and the hull 46 of the vessel. The body 41 of water provides the stability to the vessel.

Turning to figure 2, the hulls 46 are both shown with one continuous line 44 and one dashed line 45. The continuous lines 44 define the outer sides of the hulls 46, and the dashed lines define the inner sides. The keel 14 is also drawn in dashed lines as it is positioned under the deck when seen in top view.

The hulls 46 may be integrated with the deck 12.

The rotary part 7 or the keel 14 may comprise a left ballast tank 120A positioned on the left side and a right ballast tank 120B positioned on the right side of the vessel. By controllably ballasting the left and right ballast tank, the keel 14 can be rotated to its target position.

The deck 12 is connected to two arc-shaped rotary mechanisms 30.

Turning to figures 10 and 11, different embodiments of the rail 32 and the slider 34 are shown in cross-section. The rail 32 is connected to the hull 46 in a fixed manner. The rail 32 may be integral with the hull 46. The embodiment of figures 1-8 comprises four sets of rails 32 and slider 34 as shown in figure 21. The embodiment of figure 11 is an alternative to the embodiment of figure 10.

In figures 10 and 11, the forward end of the hull 46 is shown which goes over in the rail 32. The slider 34 slides along the rail 32.

The rail 32 may have the same height (or length) as the height of the hull 46. Alternatively, the rail 32 may be fully circular, so that the slider 34 and the rail 32 form two circles which are slideably arranged.

Turning to figures 7 and 8, in use, the vessel 10 is pulled with a kite via lines 110 via mounts 78, while the keel exerts a force F1 on the vessel which is substantially opposite to a force F2 of the kite. The force F1 is created by the body of water 41. The force F1 counteracts the force F2. The force F2 is drawn separate from the lines 110, but the skilled person will understand that the force F2 is exerted by the lines 110 in concerto. The force F1 travels through the center 18. The force F2 also travels through the center 18.

During sailing the kite is positioned on the starboard side 112 of the vessel and the keel is positioned on the port side 114. When the vessel tacks or jibes, the kite is moved from the starboard side to the port side and the keel 14 is moved along the circular path 16 from the port side to the starboard side.

In the embodiment of figure 7, the mounts 78 are positioned on the circle at 180 degrees from one another. In use, a kite line 110 may be partially submerged. In the embodiment of figure 8, the mounts 78 are positioned at an angle a of about 30-70 degrees. In this embodiment, the kite lines do not submerge, or at least substantially less.

The keel 14 including the rotary part 7 may be freely rotatable relative to the deck 12, so the movement from the left to the right position is caused by the force of the kite itself, and not by a human operator.

Turning to figure 9, an embodiment is shown with twin hulls 46 without an interconnecting deck 12. Instead the embodiment comprises two single decks 12. Both hulls 46 have an entry 120. The rotary mechanisms 30 are substantially the same as in the embodiment of figures 1-8

Turning to figures 12, 13 and 14, a second embodiment is shown. In this embodiment, a single rotary mechanism 30 is provided. The deck forms part of a single hull 46. The hull is relatively narrow. The rotary mechanism 30 is mounted to the hull via a pivot axis 48. The pivot axis extends horizontally from left to right. A tilting mechanism 50 is provided with which the rotary mechanism can be tilted about the lateral pivot axis 48 in order to adjust the pitch angle of the keel. The tilting mechanism comprises a hydraulic or pneumatic cylinder 51 or a rack and pinion device to tilt the rotary mechanism 30 relative to the deck 12.

The tilting mechanism may be used as a brake. If the keel 14 is oriented at a downward angle, it will function as a brake. This can be performed by extending the cylinder 51.

The pivot axis 48 pivots relative to the hull 46 but not relative to the rotary part 7. Each pivot axis is connected to the rotary 7 via a rail 32 and slider 34. This will be further explained below with reference to figure 23 and 24.

In this embodiment, the circular element forms a rotary part 7 of the rotary mechanism 30. The keel 14 is fixed to the rotary part via the front part. The keel extends rearwards from the rail. The keel is broader at the front than at the rear of the keel. In front view, the keel has an arc-shape.

The vessel 10 has a bow 60 and a stern 62.

Turning to figures 15 and 16, the rotary mechanism 30 of the embodiment of figures 10-12 is shown in more detail. The pivot axis 48 goes over in the rail 32. The circular element forms the slider 34 which slides along the rail 32. The vessel has two pivot axes, one on the left side and one on the right side of the vessel which are aligned with one another. Each pivot axis 48 goes over in a rail 32.

The rail 32 may have a limited height (or length). Alternatively, the rail 32 may be fully circular, so that the slider 34 and the rail 32 form two circles which are slideably arranged.

Turning to figures 17, 18 and 19 another embodiment is shown. In this embodiment, the vessel 10 comprises a single rotary mechanism 30 which is positioned at the bow 60 of the vessel.

The rotary mechanism 30 comprises an axle 70 and spokes 72 which extend radially from the axle 70. Three spokes 72 are provided, but a different number is conceivable. The axle is mounted to the hull 46. The axle 70 extends longitudinally and may extend substantially horizontally. A wheel 74 (or in general rotary element 74) is mounted on the axle 70 in a rotary manner. The keel 14 is fixed to the wheel. The rotary element 74 connects the keel with the spokes 72.

Turning to figures 20 and 21, an embodiment is shown wherein two arc-shaped elements 74 are provided, one at the front of the vessel and one at the rear of the vessel. Two axles 70 are provided, one at the front of the vessel and one at the rear of the vessel.

In this embodiment the spokes 72 extend upwards beyond the axle and rise out of the water into the air. The spokes provide mounts 78 for the kite at the upper ends. A beam 82 may be provided between the upper ends for further rigidity.

In another embodiment, a single spoke 72 is provided which connects the keel 14 with the axle 70.

The keel is rotatable in the direction of arrow 80 relative to the hull 46. The vessel further comprises a rudder 56 at the rear of the vessel.

Turning to figures 22, 23 and 24, another embodiment is shown. The hull 46 has a concave bottom 86. The hull 46 comprises two downward projecting hull parts 88. In use, the hull parts 88 pierce the water line and provide the buoyancy. The remainder of the hull 46 is positioned above the water line 90 in use.

The vessel may comprise a left water piercing part 88 and a right water piercing part 88 which pierce the water surface and provide stability to the vessel.

The wheel 74 rotates relative to the vessel and is connected to the hull 46 via rails 32. The wheel 74 forms the rotary part 7.

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting, but rather, to provide an understandable description of the invention.

The terms "a" or "an", as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising (i.e., open language, not excluding other elements or steps). Any reference signs in the claims should not be construed as limiting the scope of the claims or the invention.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

A kite-driven vessel (10) comprising: - a deck (12), and - a keel (14), the keel being connected to the deck via at least one turning mechanism (30), wherein viewed in front view of the vessel the keel is rotatable about a longitudinal axis (5) relative to the deck between a left position and a right position and along a path (16) which has the shape of an arc (27) of a circle (29), the longitudinal axis ( 5) is a center (18) of said circle and is spaced (28) from the keel, the keel having a first primary surface (35) and a second primary surface (36) located on either side of the keel wherein the first primary surface (35) faces both the left and right positions toward the center.

The vessel of claim 1, wherein when the vessel is oriented horizontally, the keel is inclined in the left position and right position and viewed in front view of the vessel, and wherein the first primary surface is directed upwards in the left and right position, and wherein the second primary surface is directed downwards in the left and right position and wherein a body of water (41) is clamped between the first surface facing the center and a hull (46) of the vessel and wherein: in the left position a first section (24) of the keel forms an upper part of the keel and a second section (26) of the keel (14) forms a lower part of the keel, and in the right position of the section (24) of the keel forming the lower portion of the keel and the second section (26) of the keel forming the upper portion of the keel.

The vessel of claim 1 or 2, wherein the first primary surface is concave and the opposite second primary surface is convex, and wherein the concave surface of the keel faces the center (18).

4. Vessel as claimed in any of the foregoing claims, wherein the keel is not straight when viewed in front view of the vessel, and is preferably substantially arcuate.

5. Vessel as claimed in any of the foregoing claims, wherein seen in front view, at least a part of the keel extends along the arc-shaped path, wherein in particular substantially the entire keel extends along the arc-shaped path.

A vessel according to any one of the preceding claims, wherein the keel is freely rotatable relative to the deck (12).

Vessel according to one of the preceding claims, in which the turning mechanism comprises a stationary part (6) and a rotatable part (7), the keel being attached to the rotatable part.

Vessel as claimed in any of the foregoing claims, wherein the turning mechanism comprises: - at least one rail (32), the rail standing still with respect to the deck, and a slider (34) which is arranged movably on the rail, front view the rail and the slide have an arc shape, and wherein the keel is mounted on the slide, or - a pivot axis (70), the keel being connected to the axis via one or more spokes (72).

Vessel according to one of the preceding claims, comprising two turning mechanisms (30), wherein a turning mechanism is placed essentially on the front of the vessel and wherein a turning mechanism is placed on the rear of the vessel, the keel being connected to the turning mechanisms .

Vessel according to one of claims 7 to 9, comprising at least one line attachment (78) for connecting a kite line to the vessel, the at least one line attachment being attached to the rotating part (7) of the turning mechanism.

The vessel of claim 10, wherein the line attachment is connected: - to the slider (34) or - to a rotating element (74) connecting the keel to the spokes (72).

A vessel according to any one of the preceding claims, comprising a turning mechanism that defines a full circle, and in particular comprising a circular turning mechanism located at the front of the vessel and a circular turning mechanism located at the rear of the vessel.

A vessel according to any one of claims 7-12, wherein in front view the slider (34) has a substantially annular shape, in particular a circular shape.

A vessel according to any one of the preceding claims, wherein in front view the at least one pivotal mechanism defines an opening (40) below the deck (12), the opening being formed to allow a water flow through the opening as the vessel moves forward .

A vessel according to any one of the preceding claims, wherein the vessel comprises two turning mechanisms, and wherein each turning mechanism comprises a left-hand water-cutting part and a right-hand water-cutting part that cuts the water surface and provides stability to the vessel.

A vessel according to any one of the preceding claims, wherein each turning mechanism comprises two arcuate rails (32), a left-hand rail positioned on the left-hand side of the vessel and a right-hand rail placed on the right-hand side of the vessel.

17. Vessel as claimed in any of the foregoing claims, comprising a single turning mechanism.

The vessel of any one of claims 8-17, wherein the at least one pivotal mechanism is connected to the deck via a tilting mechanism (50) configured to tilt the pivotal mechanism relative to the deck, thereby adjusting a pitch angle of the keel.

A vessel according to any one of the preceding claims, wherein the keel extends over a horizontal distance (100) and over a vertical distance (102), the horizontal distance being more than twice the vertical distance.

The vessel of any preceding claim, wherein the keel is symmetrical about a longitudinal plane (17) extending through the center (18) of the arcuate or circular path (16) and through a center (19) of the keel.

21. Vessel as claimed in any of the claims 8-20, wherein the slider and the rail form two circles which are arranged slidably with respect to each other.

Vessel according to any of claims 8-21, wherein the rotating part (7) of the turning mechanism comprises a left-hand ballast tank and a right-hand ballast tank.

A method of sailing, comprising: - providing the kite-driven vessel of claim 1, and - pulling the vessel with a kite, wherein the water exerts a force (F1) on the keel that is essentially opposite is to a force (F2) exerted by the pilot on the ship.

The method of claim 23, comprising: - positioning the kite on the starboard side (112) of the ship and positioning the keel on the port side (114), - tacking or jibbing the ship, comprising moving the pilot from starboard to port and turning the keel along the circular path from port to starboard.

The method of claim 23 or 24, wherein the vessel has at least one line attachment (78) for connecting a kite line to the vessel, the at least one line attachment being attached to a rotating part (7) of the turning mechanism, the keel rotates freely relative to the deck (12) by the force of the at least one line on the line attachment.