WATERCRAFT MANOEUVRING DEVICE AND A SURFACE WATERCRAFT INCLUDING THE MANOEUVRING DEVICE

Abstract

A watercraft manoeuvring device for mounting on a watercraft is disclosed comprising an elongate member having a mounting end and an opposed fin end that is spaced from the mounting end. The device includes a mounting formation on the mounting end for mounting on the watercraft and a fin mounted on the fin end. The fin has a bearing surface for interacting with water and the elongate member is capable of flexing when the fin is subjected to hydrodynamic water forces when travelling through water. The device may be integrally formed from a polymeric material. A watercraft such as a surfboard having the watercraft manoeuvring device is also disclosed.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is a United States National Filing, which claims priority benefit under 35 U.S.C. § 119(a) of Australian National Patent application No. 2020903492 filed Sep. 28, 2020, entitled “A Watercraft Manoeuvring Device and A Surface Watercraft Including The Manoeuvring Device”, which is incorporated herein by reference in its entireties.

TECHNICAL FIELD

This invention relates to a watercraft manoeuvring device and a surface watercraft including the manoeuvring device.

This invention relates particularly, but not exclusively, to a surface watercraft that is a surfboard, and it will be convenient to hereinafter describe this invention with reference to this example application. However, it should be clearly understood that the invention is capable of broader application. For example, it could be applied to wind surfers and also to other surface watercrafts.

BACKGROUND OF THE INVENTION

Surfboards are well known and typically comprise an elongate board having operatively upper and lower surfaces. The lower surface of the board travels across the surface of the water with one or more fins towards the rear projecting transversely down from the operatively lower surface.

The Applicant is aware of some developments in the design of the shape of fins. However, as far as Applicant is aware, in the prior art, the fins have always been directly mounted to the board and have a base that is attached to the surfboard along a base line. Thus, the base of the fin is fast with the board and while it can bend on the board it cannot be displaced relative to the board.

Each fin in its downward extending operating position has a leading edge forming a convex curve which inclines rearwards as it descends to a tip. The fin has a rear or trailing surface that rises again to the lower surface of the board. The fins are designed to cut through the water with low drag and offer high resistance in a lateral direction to limit transverse movement of the surfboard through the water. This enables a surfboard to maintain its forward trajectory along a wave while also allowing a surfer to turn the surfboard on the wave. The lateral resistance is necessary for the surfer to perform directional changes on a wave that are smooth, arcuate and controlled.

Applicant is also aware of some developments in the arrangement of fins on a surfboard. FIG. 1 illustrates an early form of surfboard having a single fin centrally positioned on the board towards the rear thereof. The manoeuvrability of the surfboard illustrated in FIG. 1, and in particular its ability to turn on a wave, is quite limited. A surfer riding a ‘single fin’ surfboard will have good straight line stability and good “projection”, meaning that the surfer can move at speed “down the line”. They can then pick a point on the wave ahead of them and by applying a strong turning force perform a smooth arcing turn of wide radius and arrive accurately and predictably at that point. The surfer may subsequently wish to perform a strong ‘cutback’ turn of sharper radius without losing speed. While a surfer having considerable skill and experience can turn tightly, given the right wave conditions, a single fin surfboard is inherently unsuited to making tight turns.

FIG. 2 illustrates a later form of prior art surfboard that became publicly available after the surfboard shown in FIG. 1 and is known as a “twin fin” board. It has two laterally spaced side fins on either side of a midline of the board. It does not have a centrally positioned fin like the board in FIG. 1. The “twin fin” was developed in competition surfing in response to a lack of an ability to make tight turns, i.e., a “stiffness” of the single fin. Substantial improvements in turning performance were achieved by replacing the single fin with two fins placed further toward the front and out toward the sides or “rails” of the surfboard. Conveniently, the surfer could perform a series of tight radius turns, with the fins alternately forming the pivot points for left and right turns. The twin fin is known to be a “loose”, free turning surfboard. However, this improvement in turning capability came at the cost of the “projection” possessed by the single fin surfboard.

FIG. 3 illustrates a later form of prior art surfboard that became publicly available after the surfboard shown in FIG. 2. The surfboard in FIG. 3 has a tri-fin arrangement towards a rear of the board and is known as a thruster. The board has two side fins on either side of a centrally positioned trailer fin. The thruster fin arrangement shown in FIG. 3 is a hybrid or combination of the surfboards in FIGS. 1 and 2 and provides a greater ability to turn on a wave, and in particular, turn sharply, than the surfboard illustrated in FIG. 1. This board thus enables a surfer to perform more intricate manoeuvres when riding a wave. This was seen as a breakthrough because the ability to manoeuvre and turn sharply on a wave is important in competition surfing. The “thruster” was developed in an attempt to capture the “projection” of the single fin, while retaining the advantageous turning ability of the twin fin. The thruster surfboard, which is a combination of the single fin and twin fin designs, has been extremely successful, and the large majority of commercially available surfboards use this design. However, the fact remains that this design remains a compromise between the twin fin and the thruster.

FIG. 4 illustrates an even later form of prior art surfboard that became publicly available after the surfboard shown in FIG. 3. The board in FIG. 4 which is known as a “quad” has a pair of side fins on one side of the midline of the board and another pair on the other side thereof. The two fins within each pair are closely spaced both laterally and longitudinally relative to each other. As shown in the drawing, the leading fin in each pair is positioned laterally outward of the trailing fin in that pair. The quad has recently seen a resurgence as surfers continue to seek the elusive optimum combination of turning ability and projection.

As far as the Applicant is aware, there have been no significant further developments in fin design or fin placement implemented on commercially available surfboards since 1985. Since then, manufacturers have energetically continued their efforts to improve the performance of leisure and competition surfboards, but the changes they have proposed essentially involve trying different combinations of known designs. Consequently, many commercially available surfboards have five fin boxes, allowing the surfer to experiment with different fin configurations, like those described above with reference to FIGS. 1 to 4. In summary, recent innovations in the manufacture of surfboards involve re-arranging and tweaking the known combinations that are discussed above.

The reference to prior art in the background above is not and should not be taken as an acknowledgement or any form of suggestion that the referenced prior art forms part of the common general knowledge in Australia or in any other country.

SUMMARY OF THE INVENTION

While the development of fin designs has provided surfboards with some manoeuvrability and an ability to change direction, Applicant recognizes that it would be beneficial if the manoeuvrability of surfboards could be further increased.

Applicant recognizes that prior art fin designs are unable to automatically adjust (i.e., auto-adjust) the angle of the fin to a line of travel through the water because the fins are rigidly fixed to the board. Applicant recognizes that it would be beneficial if a device could be devised that at least ameliorated this limitation.

According to one aspect of the invention there is provided a watercraft manoeuvring device for mounting on a watercraft operated by a user, the watercraft manoeuvring device comprising:

an elongate member having a mounting end and a fin end that is opposed to said mounting end, wherein the elongate member is capable of flexing when the device is travelling through water;

a mounting formation on or at the mounting end of the elongate member for mounting on the watercraft; and

a fin at the fin end of the elongate member having a bearing surface for interacting with water through which the fin travels.

The device helps the user to manoeuvre a watercraft as it travels across a surface of water.

The elongate member may have a length of 1 mm to 1200 mm. In some forms, the elongate member may have a length in the range of 10 mm to 500 mm. Optionally, the elongate member may have a length in the range of 20 mm to 250 mm, e.g., 30 mm to 150 mm.

The length of the elongate member can be varied to produce a device having different operational or ride characteristics.

For example, a watercraft manoeuvring device having a relatively shorter elongate member may be replaced with a device having a relatively longer elongate member.

Further, a watercraft manoeuvring device having a relatively stiffer elongate member may be replaced with a device having an elongate member with a greater whip or flexibility.

The fin on the elongate member may be resiliently flexible and may be capable of an angular deflection of up to 30 degrees from its resting position, e.g., 15 to 30 degrees. This angular deflection can be referred to as a sway angle.

The length of the elongate member influences the length of an arc through which the fin can be displaced when the elongate member flexes in use.

The elongate member may have a maximum cross-sectional dimensional extent that does not exceed 35 mm. Optionally, the elongate member may have a maximum cross-sectional dimensional extent of 10 to 30 mm, e.g., 15 to 25 mm.

The elongate member may have a cross-sectional configuration that curves around its full circumferential extent.

The elongate member may have a circular cross-sectional configuration and the elongate member may have a cross-sectional diameter in the range of 15 to 30 mm.

Instead, the elongate member may have an ovoid or elliptical cross-sectional configuration. Yet further instead, the elongate member may have a rectangular or H-shaped cross section along its length.

The elongate member may be solid. Alternatively, the elongate member may be hollow along at least part of its length.

The elongate member, the mounting formation and the fin may be integrally formed of a resiliently flexible material. Optionally, they may be formed of a polymeric material, e.g., including reinforcing materials. The reinforcing materials may include glass fibre or carbon fibre and may be in the form of a mat.

The elongate member may have a degree of flexibility or whip that is similar to that of a fishing rod.

The mounting formation may have a leading end at a forward end of the device and a rear end at a rearmost point of attachment of the device to the watercraft.

Thus, the mounting formation terminates at the rearmost point at which it is fixed to the watercraft. Correspondingly, the elongate member commences or starts after this point, namely after the rearmost point of attachment to the watercraft, and this provides a reference for measuring the length of the elongate member.

The mounting formation may be detachably mountable to the watercraft.

The mounting formation may include a projection for receiving in a complementary socket in the watercraft to detachably mount it to the watercraft.

Conveniently, the complementary socket or recess may be formed by a fin box which is permanently mounted in the board.

The mounting formation may have a low profile to streamline water flow over the formation and to minimize resistance by the mounting formation.

Further, instead of being removable, the mounting formation at the mounting end of the elongate member may be permanently mounted to the body of the watercraft.

For example, the mounting formation at the mounting end of the elongate member may be glassed, optionally with fibre, into the body of the board, e.g., in the same way a fin can be glassed into the body of a board.

The elongate member serves to rearwardly cantilever the fin on the device into a dynamic position. The elongate member has a freedom and ability to flex that enables the fin to adjust its position, e.g., angle of attack, through the water and relative to water flow. This may be referred to as a live sprung fin. Without being bound by theory, Applicant believes this streamlines water flow over the fin and allows for laminar rather than turbulent flow over the fin. Applicant also anticipates that it may release energy which is directed into forward momentum.

The fin may comprise a fin base and a fin tip and a convex leading edge extending from the fin base to the fin tip and a concave trailing edge extending from the fin tip back down to the fin base, and the fin may be fixed to the fin end of the elongate member such that the fin moves with the elongate member.

Instead of being integrally formed with the elongate member, the fin may optionally be releasably attached to the fin end of the elongate member. This feature creates the possibility for one fin to be substituted for another on the same manoeuvring device. For example, fins of various shapes and surface areas and thereby different ride characteristics may be interchangeably attached to the fin end of the elongate member.

According to another aspect of the invention there is provided a watercraft for travelling across the surface of water, the watercraft comprising:

an elongate body having an operatively upper surface for a user and an operatively lower surface for facing down into water, and

a watercraft manoeuvring device mounted on the elongate body comprising, an elongate member having a mounting end and a fin end that is opposed to said mounting end, the elongate member being capable of flexing when the device is travelling through water, a mounting formation on the mounting end of the elongate member mounted on the elongate body, and a fin on the fin end of the elongate member, e.g., having bearing surface for interacting with water through which the fin travels.

The elongate member may be resiliently flexible for flexing when travelling through water.

The watercraft manoeuvring device may be mounted on the operatively lower surface of the elongate body.

The elongate member may extend substantially parallel to the operatively lower surface of the elongate body.

Further, the elongate member may be vertically positioned at a height of not more than 100 mm beneath the operatively lower surface.

Optionally, the elongate member may be arranged vertically positioned at a height of not more than 50 mm beneath the operatively lower surface, e.g., not more than 35 mm beneath the operatively lower surface.

The mounting formation may be positioned forward of the fin of the watercraft manoeuvring device on the elongate body.

The elongate body may have a front end and a rear end, and the watercraft manoeuvring device may be mounted towards the rear end of the body.

Further, the fin of the watercraft manoeuvring device may be positioned forward of the tail of the elongate body.

The elongate body may have a center line extending along the length of the body, and the watercraft manoeuvring device may be mounted substantially along the center line of the elongate body.

The watercraft may further include at least one fixed fin directly and rigidly mounted on the operatively lower surface of the elongate body.

Optionally, the watercraft may include two said fixed fins mounted respectively on left and rights sides of the center line of the board.

The rigid fins on the left and right sides of the body may be laterally aligned with each other and may be positioned rearward of the fin of the water manoeuvring device.

The mounting formation may be detachably mounted to the elongate body to enable the device to be detached from the board and replaced with another device.

The elongate body may have a plurality of fin boxes in the operatively lower surface thereof, and each of the fin boxes may be configured to releasably clamp the mounting formation of the water craft manoeuvring device to the elongate body.

Providing a plurality of fin boxes positioned on the elongate body provides a user with a plurality of different options for positioning the elongate member in different positions on the device. For example, the several options enable the user to vary the position of the device on the elongate body. It also enables the user to select devices having different lengths of elongate member without significantly changing the longitudinal position of the fin of the device.

Alternatively, the watercraft manoeuvring device may be mounted on an operatively upper surface of the elongate body.

Further alternatively, the watercraft manoeuvring device may be mounted on the rear end of the elongate body.

The watercraft manoeuvring device of the watercraft may include any one or more of the optional or preferred features of the watercraft manoeuvring device defined in any preceding aspect of the invention.

Optionally, the watercraft may be a surfboard. Instead, the watercraft may be a windsurfer.

According to yet another aspect of the invention there is provided a surfboard comprising:

an elongate board having a nose and a tail and two rails extending between the nose and the tail, an operatively upper surface forming a deck on which a user stands and an operatively lower surface for facing down into water; and

a watercraft manoeuvring device mounted on the elongate board comprising, an elongate member having a mounting end and a fin end that is opposed to said mounting end, wherein the elongate member is capable of flexing when the board is travelling through water, a mounting formation on the mounting end of the elongate member mounted on the lower surface, and a fin on the fin end of the elongate member.

The elongate member may have a length of 1 mm to 500 mm. Optionally, the elongate member may have a length of 30 to 150 mm.

The elongate member may extend substantially parallel to the operatively lower surface of the board.

The elongate member may be positioned a vertical distance, e.g., a height of not more than 100 mm beneath the operatively lower surface. Optionally, the elongate member may be vertically positioned at a height of not more than 50 mm beneath the operatively lower surface

The elongate member may have a cross-sectional configuration that curves around its full circumferential extent, and the elongate member may have a maximum diameter of 30 mm.

Optionally, the elongate member may have a maximum diameter in the range of 15 to 30 mm, e.g., 15 to 25 mm.

Optionally, the elongate member may have a circular or ovoid or elliptical cross-sectional configuration.

The watercraft manoeuvring device may be integrally formed from a polymeric material, and the mounting formation may be detachably mounted on the board whereby to enable the device to be detached from the board and replaced with another device.

The watercraft manoeuvring device may be mounted on a center line of the board, and the board may further include left and right fixed fins on left and right sides of the center line that are directly mounted to the board (and cannot alter their angle of travel relative to the board).

The watercraft manoeuvring device and the left and right fixed fins may be mounted in suitable positions on the board to enable the longitudinal and lateral positions of the fin of the device and the fixed fins collectively to resemble a tri fin thruster configuration.

That is, the fins are mounted in basically the same position as the fins on a thruster. However, the central fin forms part of a manoeuvring device that has an elongate member which can flex and consequently the fin can alter its line of travel through the water.

The one and other fixed fins may be bilaterally symmetrical on the body, e.g., they may be laterally aligned on the body and may be spaced an equal distance from the midline.

The watercraft manoeuvring device on the surfboard may include any one or more of the optional or preferred features of the watercraft manoeuvring device defined in any preceding aspect of the invention.

The invention extends to a method of modifying a watercraft, e.g., a surfboard having an elongate board with at least one removable fin on an underside of the board, the method including:

removing a fin from an underside of the board and replacing it with a watercraft manoeuvring device as defined in any one of the preceding aspects of the invention.

The removable central fin may be removably mounted on the board by means of a clamp which releasably clamps the fin into a fin box mounted in the board.

Removing the central fin may include releasing the clamp and withdrawing the fin, e.g., a central fin, from the fin box.

Replacing the central fin with a surfboard manoeuvring device may include inserting the surfboard manoeuvring device into the fin box and clamping it to the fin box.

The watercraft manoeuvring device of the surfboard may include any one or more of the optional or preferred features of the watercraft manoeuvring device defined in any preceding aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A watercraft manoeuvring device and a surface watercraft that is a surfboard including the manoeuvring device in accordance the invention may manifest itself in a variety of forms. It will be convenient to hereinafter describe in detail several embodiments of the invention with reference to the accompanying diagrammatic drawings. The purpose of providing this detailed description is to instruct persons having an interest in the subject matter of the invention how to carry the invention into practical effect. However, it is to be clearly understood that the specific nature of this detailed description does not supersede the generality of the preceding summary section.

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the disclosure and together with the detailed description herein, serve to explain the principles of the disclosure. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. The drawings are only for purposes of illustrating preferred embodiments and are not to be construed as limiting the disclosure.

FIG. 1 is a lower perspective view of a surfboard in accordance with the prior art having a single tail fin centrally positioned on the board, in accordance with an aspect of the present disclosure;

FIG. 2 is a lower perspective view of another surfboard in accordance with the prior art having two laterally spaced side fins mounted on the board, in accordance with an aspect of the present disclosure;

FIG. 3 is a lower perspective view of yet another surfboard in accordance with the prior art having three tail fins mounted on the board, in accordance with an aspect of the present disclosure;

FIG. 4 is a lower perspective view of yet another surfboard in accordance with the prior art having two pairs of tail fins, one pair being mounted on each side of the board, in accordance with an aspect of the present disclosure;

FIG. 5 is a lower perspective view of a watercraft manoeuvring device that is a surfboard manoeuvring device in accordance with one embodiment of the invention;

FIG. 6 is a bottom plan view of the surfboard manoeuvring device of FIG. 5, in accordance with an aspect of the present disclosure;

FIG. 7 is a front view of the surfboard manoeuvring device of FIG. 5 mounted on a surfboard, in accordance with an aspect of the present disclosure;

FIG. 8 is a side view of the surfboard manoeuvring device of FIG. 5 mounted on a surfboard, in accordance with an aspect of the present disclosure;

FIG. 9 is a lower perspective view of a surfboard fitted with the surfboard manoeuvring device of FIG. 5, in accordance with an aspect of the present disclosure;

FIGS. 10 and 11 illustrate different embodiments of surfboard manoeuvring devices mounted on a surfboard like that shown in FIG. 9, in accordance with an aspect of the present disclosure;

FIG. 12 is a schematic side view of a surfboard having a surfboard manoeuvring device in accordance with another embodiment of the invention mounted thereon, in accordance with an aspect of the present disclosure;

FIG. 13 is a schematic side view of a surfboard having a surfboard manoeuvring device in accordance with yet another embodiment of the invention mounted thereon, in accordance with an aspect of the present disclosure;

FIGS. 14 and 15 are schematic side and plan views of a surfboard having a surfboard manoeuvring device in accordance with yet another embodiment of the invention mounted thereon, in accordance with an aspect of the present disclosure;

FIG. 16 is a schematic drawing of the watercraft manoeuvring device in accordance with an embodiment of the invention mounted on a surface watercraft that is a windsurfer, in accordance with an aspect of the present disclosure; and

FIG. 17 is a schematic drawing of a surfboard in accordance with another embodiment of the invention, in accordance with an aspect of the present disclosure.

DETAILED DESCRIPTION FOR CARRYING OUT THE INVENTION

FIGS. 1 to 4 illustrate surfboards that are known in the prior art. The fin arrangements illustrated in FIGS. 1 to 4 have been described above in the background section of the specification. As these prior art surfboards do not form part of the invention claimed in this application, they will not be described further in this detailed description.

FIGS. 5 to 8 illustrate a watercraft manoeuvring device that is a surfboard manoeuvring device for mounting on an operatively lower surface or bottom of a body or hull of a surfboard. In the drawings, reference numeral 10 refers generally to the surfboard manoeuvring device.

The surfboard manoeuvring device 10 comprises broadly an elongate member or boom 12 including a mounting end 14 and a fin end 18. The mounting end 14 has a mounting formation 16 for detachably mounting the device 10 to the lower surface of a watercraft, and an opposed fin end 18. The device 10 further includes a fin 20 on the fin end 18 of the elongate member 12 for interacting with the water through which the surfboard travels.

The mounting formation 16 extends from its forward attachment to the board to its rear point of attachment to the board. The elongate member 12 starts at the rearmost point at which the mounting formation is fixed to the board. This provides a reference point for measuring the length of the elongate member 12. This is also consistent with the concept that the elongate member 12 is free to flex relative to the board and is not fixed or held to the board like a mast.

The elongate member 12 is formed of a resilient material having some stiffness but which can bend along its length when it is subjected to forces from the water through which it travels. In one example form, the elongate member 12 has a length of 10 to 300 mm and a substantially circular, an elliptical or an ovoid cross-sectional shape that is constant along its length. The rounded cross-sectional configuration of the elongate member 12 helps to streamline the member 12 and reduce drag. The elongate member or boom 12 may be rod-like and be formed from a resilient material that can flex along its length and then return to its original form repeatedly without suffering any loss of stiffness in the material. The desired flexural performance of the elongate member 12 is achieved by appropriate selection of material, thickness, and length, and also by selecting a suitable profile for the member.

Conveniently, the surfboard manoeuvring device 10 may be integrally formed from a polymeric material, optionally with some fibre and composite material that provides a suitable strength and that also confers a desired flexibility. The existence of high performing plastics such as polycarbonate, polyamide (NYLON), acetyl or acetal resins and thermo-setting resins such as epoxy and polyester, and also carbon fibre, enables the elongate member 12 to be manufactured with a desired stiffness while still being resilient. It also enables the entire manoeuvring device 10 to be integrally formed in one unitary piece by CNC machining, injection moulding or by hand lay up. Optionally, the surfboard manoeuvring device can also be made of a sustainable material such as bamboo.

FIG. 9 illustrates a surfboard indicated generally by the reference numeral 30 comprising an elongate body or board 32 having an operatively upper surface or deck 34 and an operatively lower surface or bottom 36 extending between a front end or nose 37 and an opposed rear end or tail 38. The board also has rails extending down its sides between the nose 37 and the tail 38.

The surfboard 30 has a fin arrangement towards the rear end 38 of the body 32 for helping a surfer to manoeuvre the surfboard on a wave. In the illustrated embodiment, the fin arrangement comprises two conventional surfboard fins or rigid side fins 42, 44, one on either side of the body 32, and a surfboard manoeuvring device 10 like that in FIGS. 5 to 8 which is mounted substantially centrally between the two side fins 42, 44 a small distance rearward of the side fins 42, 44.

In the illustrated embodiment, the mounting formation 16 at the mounting end 14 of the resilient member 12 comprises a couple of mounting protrusions or projections 52, 54 that project away from the mounting end 14 of the member 12 that are tightly received within complementary sockets or apertures 56 within a fin box on the body 32 of the board 30. The fin box is a commercially available product is built into the surfboard by the board manufacturers during the manufacture thereof.

The projections 52, 54 are clamped to the body 32 in the fin box in accordance with known techniques. In the illustrated embodiment, the surfboard manoeuvring device 10 is releasably clamped, to the body 32 which is very useful. It enables the surfboard manoeuvring device 10 to be quickly and easily detached and removed from the surfboard 30. It can then be replaced with another surfboard manoeuvring device 10, e.g., of a different size and having different operational properties.

FIG. 17 illustrates a surfboard that is a variation on the surfboard described above with reference to FIG. 9. The same reference numerals will be used to refer to the same components unless otherwise indicated.

In FIG. 17, the mounting formation 16 is positioned forward on the board 32 relative to that in FIG. 9. This has a follow on effect that the fin 20 of the device 10 is positioned in substantially the same longitudinal position as a central fin in a tri-fin thruster arrangement. Further, the elongate member travels close to the bottom of the board parallel to the surface of the board and thus the fin of the device is in a very similar vertical position to the central fin of a prior art thruster fin arrangement. Thus, this arrangement mimics the tri fin thruster and the board visually resembles a regular surfboard with a widely used tri-fin thruster. The surfboard in FIG. 17 in a broad sense facilitates the same surfing manoeuvres as those carried out with a thruster. However, it performs better than the prior art thruster for the reasons described in this specification.

If the position of the fin 20 of the device 10 along the length of the board 32 is to be set as described immediately above, then one way to accommodate different lengths of elongate member 12 is to move the axial position of the mounting formation 16 along the board. If, for example, a device 10 with longer elongate member 12 is desired to be used on the board of FIG. 17, then the mounting formation 16 can be moved forward on the board 32 to keep the fin 20 of the device 10 in substantially the same longitudinal position. A range of fin boxes arranged in different axial positions on the bottom of the board facilitates this optionality.

In use, the surfboard manoeuvring device 10 is mounted on a surfboard 30 in the manner shown in FIG. 7. That is, the surfboard manoeuvring device 10 is centrally mounted on the operatively lower surface 36 of the body 32 towards the rear end 38 thereof. The surfboard manoeuvring device 10 is mounted on the body 32 by inserting the mounting formations 52, 54 into the complementary sockets 56 in the board 32 and clamping the mounting formations thereto.

The surfboard manoeuvring device 10 provides the user of the surfboard 30 or surfer with an enhanced ability to manoeuvre the surfboard 30. In particular, flexing of the elongate member 12 of the device increases the power of the surfboard 30 as it travels through the water. It also enables the surfer to control their movements across the water surface more precisely.

FIGS. 10 and 11 illustrate surfboard manoeuvring devices in accordance with further embodiments of the disclosure. In FIGS. 10 and 11, unless otherwise indicated, the same reference numerals will be used to refer to the components as in FIGS. 5 to 8. Further, the following description will focus on the main differences between the embodiments in FIGS. 10 and 11 and the embodiments in the earlier embodiment shown in FIGS. 5 to 8.

In FIG. 10, the device 10 has a shorter elongate member 12 than the elongate member of the device 10 in FIGS. 5 to 8. As shown in the drawing, the device 10 terminates short of the rear end 38 of the surfboard 32. The effect of the shorter member 12 on the operation of the surfboard will be to impart good projection and a stiffer feel when turning the surfboard.

In FIG. 11, the device 10 has a longer elongate member than the elongate member 12 on the device 10 in FIGS. 5 to 8. In particular in FIG. 11, the fin of the device 10 projects out beyond the rear end 38 of the board 32. The effect of this change on the operation of the board will depend on the stiffness of the elongate member. A longer but relatively stiffer elongate member 12 will impart good directional projection to a short surfboard fitted with the device 10. A relatively more flexible elongate member 12 will impart a greater turning ability to the surfboard.

FIG. 12 is a schematic side view of a surfboard fitted with a surfboard manoeuvring device in in accordance with another embodiment of the invention. Again, the same reference numerals will be used to refer to the same components and the following description will focus on the difference between this embodiment and the earlier embodiments.

In the FIG. 12 embodiment, the surf craft manoeuvring device 10 is mounted to an upper surface or deck 34 of the body 32 or board of the surfboard 30 (instead of the lower surface 36). The device 10 may have a mounting formation 16 mounted in a fin box similar to that used on the lower surface 36 of the board 32.

FIG. 13 is a schematic side view of a surfboard fitted with a surfboard manoeuvring device in accordance with yet another embodiment of the invention. Once again, the same reference numerals will be used to refer to the same components unless otherwise indicated and the description will focus on the differences between this embodiment and the earlier embodiments.

In FIG. 13, the surf craft manoeuvring device 10 is mounted to the rear end 38 of the board 32 of the surfboard 30. The board 32 has a fin box within which a mounting formation 16 on the device 10 is received.

FIGS. 14 and 15 are schematic side and plan views of a surfboard fitted with a surfboard manoeuvring device in accordance with yet another embodiment. Once again, the same reference numerals will be used to refer to the same components unless otherwise indicated and the following description will focus on the difference between this embodiment and the earlier embodiments.

In FIGS. 14 and 15, the device is mounted to an operatively lower surface or bottom 36 of the surfboard 30 towards the tail 38 thereof. The device 10 has a fin 200 having bearing surfaces extending in a substantially horizontal direction whereas the fin 20 of the earlier embodiments has bearing surfaces extending in a vertical direction. The bearing surfaces extend laterally away from both sides of the elongate member 32 or flex boom.

The elongate member 12 turns down towards the fin end 18 that transitions into the fin 20. This positions the fin 20 at a suitable distance or vertical height beneath a surface of water to enable it to apply a force to water passing over an upper surface of the fin 200 without leaving the water. The design of the fin 200 allows the user to propel the surfboard 30 forward by a rocking up and down leg driving motion known in surfing as ‘leg pumping’.

FIG. 16 shows the watercraft manoeuvring device mounted to a windsurfer. Once again, the same reference numerals will be used to refer to the same components unless otherwise indicated and the following description will focus on the difference between this embodiment and the earlier embodiments.

The windsurfer is referred to generally by the numeral 60 and comprises a windsurfer body 62 having an operatively upper surface or deck and an operatively lower or water facing surface. The watercraft manoeuvring device 10 is mounted to the windsurfer 60 towards the rear of the body 62 in a similar manner to the mounting to a surfboard.

In use, the watercraft manoeuvring device 10 functions in a similar manner to the device used on the surfboard. Its main advantage is its ability to self-adjust the angle of the fin to the water flow. The hull of a wind surfer frequently leaves the water during use. It takes a skilled user to return the hull to the water at exactly the right angle. The device of this invention enables the fin of the device to auto adjust on its return to the water.

The prior art fins, such as those shown in FIGS. 1 to 4, can be constructed to have two foundation axes. The axes comprise a vertical mast axis extending perpendicularly away from the board and a horizontal boom axis extending rearward from the vertical mast axis. The mast and the boom are bearing surfaces that bear against the water through which the board is passing. Further, prior art fins have a base or foot that is fixed directly to the board and cannot move relative thereto in use. The Applicant has found no exceptions to this mode of fin construction in the prior art.

In the current application, the fin of the watercraft manoeuvring device is axially separated from the mounting formation which mounts it to the surfboard. Thus, the device illustrated above with reference to the drawings differs from the prior art fins in that it has no vertical mast fast with the board and extending away therefrom that acts as a bearing surface.

The illustrated embodiments of fins and devices in accordance with the current disclosure have no vertical mast. Instead, the devices have an elongate member in the form of a stanchion or knuckle member attached to the board that presents no bearing surface. Rather, the stanchion has a fin having a bearing surface at a remote end thereof which moves with the stanchion and is not directly fixed to the board.

The watercraft manoeuvring device, by means of the elongate member or stanchion, enables the fin to auto adjust its angle through the water to an angle of least resistance through the water. The elongate member can flex in response to hydrodynamic water forces that are applied thereto and can self-adjust the angle of the fin relative to the surfboard body. The change in angle of the fin can occurs without bending or distorting the fin which itself would alter the performance of the fin.

The fin has a bearing surface for interacting with water and the elongate member is capable of flexing when the fin is subjected to hydrodynamic water forces when travelling through water. This feature of self-adjusting the angle of the fin enables the surfboard to turn smoothly and also avoids a stalled fin situation because it provides for more streamlined flow over the surface of the fin. There is less turbulence and consequently less drag to cause the surfboard to stall.

Applicant is aware of high performing polymeric and composite materials that make it possible to manufacture an elongate member that is stiff but also flexes resiliently as the device travels through the water. The flexing and resilience also stores, and then releases spring energy which is directed into forward momentum.

An advantage of the surfboard described above with reference to FIGS. 5 to 17 is that it provides a surfer with increased manoeuvrability and power when surfing a wave. It therefore provides a more exciting surfing experience than a prior art surfboard having traditional fixed fins. Applicant also anticipates that a surfer using a board fitted with the device would be able to use known ‘leg pumping’ techniques to drive the board forward through the water.

The device can be used in combination with two side fins so that they together resemble a prior art thruster fin arrangement on a surfboard. That is, the three fins (including the fin of the manoeuvring device) are positioned in broadly the same relative position to each other and the board as with the prior art thruster. The mounting formation for the device 10 will be positioned more forward on the board than the mounting formation of a central fin of a thruster fin arrangement. This enables the actual fin 20 on the device 10 to be positioned in the same axial position as it would occupy with a thruster fin arrangement. Additionally, the elongate member extends parallel to the surface of the board so that the height of the fin on the device is at broadly the same height as the central fin of the thruster arrangement.

Without being bound by theory, Applicant believes that the device described above with reference to the drawings mimics the propulsive properties of fluke fins of whales and dolphins in nature. Finally, Applicant believes that the current disclosure opens the door to a fresh chapter of development in surfboard design and performance.

It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. All such modifications and variations thereto, as would be apparent to persons skilled in the art, are deemed to fall within the broad scope and ambit of the invention as is set forth herein. Changes in detail or structure may be made without departing from the basic elements of the invention as defined in the following claims.

Claims

1. A watercraft manoeuvring device for mounting on a watercraft, the watercraft manoeuvring device comprising: an elongate member having a mounting end and a fin end that is opposed to said mounting end, wherein the elongate member is capable of flexing;a mounting formation on the mounting end of the elongate member for mounting on the watercraft; anda fin at the fin end of the elongate member having a bearing surface for interacting with water through which the fin travels.

2. The watercraft manoeuvring device of claim 1, wherein the elongate member has a length of 1 mm to 1200 mm.

3. The watercraft manoeuvring device of claim 1, wherein the fin on the elongate member is capable of an angular deflection of 15 to 30 degrees from its resting position due to flexing of the elongate member during use.

4. The watercraft manoeuvring device of claim 1, wherein the elongate member has a cross-sectional configuration that curves around its full circumferential extent, and the elongate member has a maximum cross-sectional dimensional extent that does not exceed 30 mm.

5. A watercraft manoeuvring device of claim 1, wherein the elongate member, the mounting formation and the fin are integrally formed of a resiliently flexible material, and the mounting formation is detachably mountable to the watercraft.

6. The watercraft manoeuvring device of claim 5, wherein the mounting formation has a leading end at a forward end of the device and a rear end at a rearmost point of attachment to the watercraft, and the mounting formation includes a mounting projection for inserting in a complementary socket in the watercraft to detachably mount the device to the watercraft.

7. A watercraft for travelling across the surface of water, the watercraft comprising: an elongate body having an operatively upper surface for a user and an operatively lower surface for facing down into water, anda watercraft manoeuvring device mounted on the elongate body, comprising an elongate member having a mounting end and a fin end that is opposed to said mounting end, the elongate member being capable of flexing when the device is travelling through water, a mounting formation on the mounting end of the elongate member mounted on the elongate body, and a fin on the fin end of the elongate member.

8. The watercraft for travelling across the surface of water of claim 7, wherein the elongate body has a front end and a rear end, and the watercraft manoeuvring device is mounted on the operatively lower surface of the elongate body towards the rear end thereof.

9. The watercraft for travelling across the surface of water of claim 7, wherein the elongate member extends substantially parallel to the operatively lower surface of the elongate body, and the elongate member is positioned a vertical distance of not more than 100 mm beneath the operatively lower surface of the body.

10. The watercraft for travelling across the surface of water of claim 7, wherein the elongate body has a center line extending along a length of the elongate body and the watercraft manoeuvring device is mounted on the center line of the elongate body.

11. The watercraft for travelling across the surface of water of claim 10, wherein the watercraft is a surfboard and further includes at least one fixed fin rigidly mounted on the operatively lower surface of the elongate body.

12. The watercraft for travelling across the surface of water of claim 11, including two said fixed fins mounted respectively on left and rights sides of the center line of the board.

13. The watercraft for travelling across the surface of water of claim 12, wherein the fixed fins on the left and right sides of the body are laterally aligned with each other and the fixed fins are positioned forward of the fin of the water manoeuvring device.

14. The watercraft for travelling across the surface of water of claim 7, wherein the mounting formation is detachably mounted to the elongate body, and the elongate body has a plurality of fin boxes in the operatively lower surface, and each fin box is configured to releasably clamp the mounting formation of the water craft manoeuvring device to the elongate body.

15. A surfboard comprising: an elongate board having a nose and a tail and two rails extending between the nose and the tail, an operatively upper surface forming a deck on which a user stands and an operatively lower surface facing down; anda watercraft manoeuvring device mounted on the elongate board comprising, an elongate member having a mounting end and a fin end that is opposed to said mounting end, wherein the elongate member is capable of flexing when the board is travelling through water, a mounting formation on the mounting end of the elongate member that is mounted on the lower surface, and a fin on the fin end of the elongate member.

16. The surfboard of claim 15, wherein the elongate member has a length of 1 mm to 500 mm, and the elongate member extends substantially parallel to the operatively lower surface of the board.

17. The surfboard of claim 16, wherein the elongate member has a length of 30 to 150 mm, and the elongate member is positioned a vertical distance of not more than 50 mm beneath the operatively lower surface.

18. The surfboard of claim 15, wherein the elongate member has a cross-sectional configuration that curves around its full circumferential extent, and the elongate member has a maximum diameter of 15 to 30 mm.

19. The surfboard of claim 15, wherein the watercraft manoeuvring device is integrally formed from a polymeric material, and wherein the mounting formation is detachably mounted on the board whereby to enable the device to be detached from the board and replaced with another device.

20. The surfboard of claim 15, wherein the watercraft manoeuvring device is mounted on a center line of the board, and the board further includes left and right fixed fins on left and right sides of the center line that are directly mounted to the board, and wherein the watercraft manoeuvring device and the left and right fixed fins are mounted on the board such that the longitudinal and lateral positions of the fin of the device and the fixed fins resemble a tri fin thruster configuration.