AU2021107645A4 - A watercraft manoeuvring device and a surface watercraft including the manoeuvring device - Google Patents

Abstract

: A watercraft manoeuvring device for mounting on a watercraft is disclosed comprising 5 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 on the fin end. The fin has a bearing surface for interacting with the water through which the watercraft travels and is resiliently flexible such that it can flex when the fin is subjected to forces when it travels through the water. 10 The device may be integrally formed from a polymeric material. A watercraft and a surfboard having a watercraft manoeuvring device is also disclosed. Figure 8 4/10 too 56 Fiur 7 *3 366 121 Fiur*

Description

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A WATERCRAFT MANOEUVRING DEVICE AND A SURFACE WATERCRAFT INCLUDING THE MANOEUVRING DEVICE 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.

DEFINITION

In the present disclosure and claims, the term "comprising" shall be understood to have a broad meaning similar to the term including" and will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. This definition also applies to variations on the term "comprising" such as "comprise" and comprises".

BACKGROUND

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 development in the design of the shape of fins per se. 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 translationally displace relative to the board.

Each fin, when 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 limiting transverse movement of the surfboard through the water. The fins enable a surfboard to maintain its forward trajectory along a wave while also allowing the surfer to turn the board on the wave. The lateral resistance is necessary for the surfer to perform directional changes on a wave which are smooth, arcuate and controlled.

Figure 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 Figure 1, and in particular its ability to turn on a wave, is quite limited. A surfer riding a 'single fin' surfboard will find that it has 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 can 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, the single fin surfboard is inherently unsuited to making tight turns.

Figure 2 illustrates a later form of prior art surfboard that became publicly available after the surfboard shown in Figure 1 that 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 Figure 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 U-turns, with the fins alternately forming the pivot points for the 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" capability possessed by the single fin surfboard.

Figure 3 illustrates a later form of prior art surfboard that became publicly available after the surfboard shown in Figure 2. The surfboard in Figure 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 surfboard in Figure 3 is a hybrid or combination of the surfboards in Figures 1 and 2 and provides a greater ability to turn on a wave, and in particular, turn sharply, than the surfboard illustrated in Figure 1. This board thus enables a surfer to perform more intricate manoeuvres when riding a wave and the ability to manoeuvre and turn sharply on a wave became an important feature in competitive surfing. The "thruster" was developed in an attempt to recapture 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 very successful, and the large majority of commercially available surfboards have this design. While this design has undoubtedly been successful, it remains a compromise between the twin fin and the thruster and does not represent a perfect solution.

Figure 4 illustrates an even later form of prior art surfboard that became publicly available after the surfboard shown in Figure 3. The board in Figure 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 since 1985, that have been implemented on commercially available surfboards. 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 Figures 1 to 4.

As far as Applicant is aware, recent innovation in the surf craft industry consists of 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 DISCLOSURE

Applicant recognises that the development of fin design has provided surfboards with a greater manoeuvrability and ability to change direction.

However, Applicant also recognises that it would be beneficial if some new and different features could be devised that increase the manoeuvrability of surfboards.

Applicant has recognised 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 and provide an ability to flex and change direction while leaving the shape of the fin unchanged. Applicant recognises that it would be beneficial if a device could be devised that at least ameliorated this limitation.

According to one aspect of this disclosure, there is provided a watercraft manoeuvring device for mounting on a watercraft, the watercraft manoeuvring device comprising: an elongate member having a mounting end and an opposed fin end that is spaced from the mounting end; a mounting formation at the mounting end of the elongate member for mounting on the watercraft; and a fin on the fin end of the elongate member having a bearing surface for interacting with the water through which the watercraft travels, wherein the elongate member is flexible such that it can flex when the fin is subjected to forces when it travels through the water

This helps a user to manoeuvre the watercraft through the water.

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 also release energy which is directed into forward momentum.

Conveniently, the watercraft manoeuvring device may be mounted on an operatively lower surface of the watercraft.

The elongate member may extend parallel to the operatively lower surface of the water craft and be spaced a short distance beneath the operatively lower surface.

The elongate member may be spaced a distance below the operatively lower surface that is not more than one half of the height of the fin. In some forms, the elongate member is closely spaced below the operatively lower surface, e.g., 10-50 mm below the lower surface.

In use, the fin may be positioned forward of a tail of the watercraft on which it is mounted.

Alternatively, in some less preferred embodiments, the watercraft manoeuvring device may be mounted on an operatively upper surface of the watercraft. Further, alternatively, the watercraft manoeuvring device may be mounted on an end of the watercraft.

The fin which extends downward in use may have a leading edge forming a convex curve which inclines rearwards as it descends to a tip. The fin may have a rear or trailing surface that rises up from the tip with a curved configuration, e.g., a concave configuration that is broadly complementary to the convex curve on the leading edge.

The watercraft manoeuvring device may be integrally formed of a resiliently flexible material so that it can bend and flex in use.

Conveniently, the watercraft manoeuvring device may be formed from a polymeric material and optionally the polymeric material may have some reinforcing additives contained therein.

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

The mounting formation terminates at the rearmost point at which it is fixed to the watercraft. Correspondingly, the elongate member commences or starts at this point, namely after the rearmost point of attachment of the mounting formation to the board.

The mounting formation at the mounting end of the elongate member may be releasably or detachably mounted to the body of the watercraft.

In particular, the mounting formation at the mounting end of the elongate member may comprise a projection or protrusion for receiving in a complementary socket or recess in the body of the watercraft and clamping thereto. Conveniently, the complementary socket or recess may be formed by a fin box which is securely and permanently mounted in the board.

The feature of having the mounting formation detachably mounted to the body of the watercraft is that it enables a given watercraft manoeuvring device to be detached from the watercraft and be replaced with another watercraft manoeuvring device, e.g., 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 elongate member may have a length of 1mm to 1200mm.

In some forms, the elongate member has a length of 10mm to 500mm. Optionally, the elongate member may have a length in the range of 50 to 500mm.

The elongate member may have a constant cross-sectional configuration along its length.

The elongate member may have an outer surface that is curved, e.g., in a direction transverse to the direction of elongation. For example, the elongate member may have a cross-sectional configuration that is curved around its full circumferential extent. The elongate member may have a circular cylindrical cross-sectional configuration. Instead, the elongate member may have an ovoid or an elliptical cross-sectional configuration.

Yet further instead, the elongate member may conceivably 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.

It is anticipated that the fin may undergo an angular deflection, e.g., from a centreline or axially extending line, of between 10 and 30 degrees. For example, applicant believes that an optimal maximum angular deflection may be about 30 degrees.

The watercraft manoeuvring device may have a degree of flexibility, e.g., a flexibility similar to a fishing rod.

Further, the fin may be releasably attached to the rearward end of the elongate member. This feature creates the possibility for one fin to be substituted for another. For example, fins of various shapes and surface areas and thereby different ride characteristics may be interchangeably fitted to the rearward end of the elongate member.

Instead, the fin may be integrally formed with the elongate member.

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 mounting formation at the mounting end of the elongate member may be releasably or detachably mounted to the body of the watercraft.

The watercraft manoeuvring device may optionally be integrally formed of a polymeric material. This can be convenient to manufacture a manoeuvring device having an elongate member of suitable strength.

According to another aspect of this disclosure, there is provided a watercraft for travelling across the surface of water, the watercraft comprising: an elongate body having an operatively upper surface for carrying a surfboard rider and an operatively lower surface for facing down into the water, and a watercraft manoeuvring device as defined in any one of the preceding aspects of the disclosure, mounted on the elongate body for assisting a user to manoeuvre the watercraft through the water.

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

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

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 body may have a midline extending along the length of the body dividing the body up into left and right sides, e.g., and the body may be bilaterally symmetrical on left and right sides of the midline.

The watercraft may include at least one rigid fin that is rigidly mounted on the operatively lower surface of the body.

For example, the watercraft may include a single rigid fin centrally mounted on the lower surface of the body.

The watercraft may further include one rigid fin on the left side of the body and another rigid fin on the right side of the body, e.g., instead of or in addition to the single rigid fin.

The rigid fin on the left and right sides of the body may be positioned forward of the fin of the water manoeuvring device.

In fact, the left and right fins and the fin of the device may be positioned in similar positions to those of a tri fin thruster configuration. That is, the fins are basically in the same position as with 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 attack in the water.

The one and other rigid 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 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.

Conveniently, the watercraft may be a surfboard.

According to yet another aspect of the disclosure, there is provided a surfboard comprising: an elongate board having an operatively upper surface and an operatively lower surface for facing down into the water; and a surfboard manoeuvring device as defined in any one of the preceding aspects of the disclosure, mounted on the operatively lower surface for assisting a user to manoeuvre the surfboard through the water.

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

In particular, the surfboard may further include two side fins rigidly mounted on left and rights sides or left and right rails of the board.

The elongate board may have a front end or nose and a rear end or tail, and the surfboard manoeuvring device may be positioned towards the rear or tail of the board and the two side fins may also be mounted towards the rear end of the board.

The surfboard also has a deck on which the user stands and a bottom that faces down into the water in use.

The invention extends to a method of modifying a surfboard having an elongate board with at least one removable fin on an underside of the board, the method including: removing a central fin from an underside of the board and replacing it with a surfboard 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 and removing the central fin may include releasing the clamp and withdrawing the 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 tight.

BRIEF DESCRIPTION OF THE DRAWINGS

A watercraft manoeuvring device and a surface watercraft 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. In the drawings:

Figure 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;

Figure 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;

Figure 3 is a lower perspective view of yet another surfboard in accordance with the prior art having three tail fins mounted on the board;

Figure 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;

Figure 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;

Figure 6 is a bottom plan view of the surfboard manoeuvring device of Figure 5;

Figure 7 is a front view of the surfboard manoeuvring device of Figure 5;

Figure 8 is a side view of the surfboard manoeuvring device of Figure 5;

Figure 9 is a lower perspective view of a surfboard fitted with the surfboard manoeuvring device of Figure 5;

Figures 10 and 11 illustrate different embodiments of surfboard manoeuvring devices fitted to a surfboard like that shown in Figure 9;

Figure 12 is a schematic side view of a surfboard fitted with a surfboard manoeuvring device in accordance with another embodiment of the invention;

Figure 13 is a schematic side view of a surfboard fitted with a surfboard manoeuvring device in accordance with yet another embodiment of the invention;

Figures 14 and 15 are schematic side and plan views of a surfboard fitted with a surfboard manoeuvring device in accordance with yet another embodiment of the invention; and

Figure 16 is a schematic drawing of the watercraft manoeuvring device mounted to a windsurfer; and

Figure 17 is a schematic drawing of a surfboard in accordance with another embodiment of the invention.

DETAILED DESCRIPTION

Figures 1 to 4 illustrate surfboards that are known in the prior art. Their features particularly the fins that they utilise 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.

Figures 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 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 watercraft travels.

The mounting formation 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. It is not fixed or held to the board like a mast.

The elongate member or boom 12 may be rod-like and formed from a resilient material that is rigid but can flex along its length and return repeatedly to its original form without suffering any loss of stiffness or integrity of internal material. The desired flexural performance of the elongate member 12 is achieved by appropriate selection of material, thickness, profile and length. In one example form, the elongate member 12 typically has a length of 10 to 300mm and a substantially circular, elliptical or ovoid cross sectional shape that is constant along its length. The elongate member 12 is formed of a resilient material that is rigid but can bend along its length in use when it is subjected to forces from the water through which it passes.

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 the desired flexibility. The existence of high performing plastics such as polycarbonate, NYLON, acetyl or acetal resins and fibre reinforced thermo-setting resins such as epoxy polyester and carbon fibre enable 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. Bamboo is also an option which uses sustainable materials.

Figure 9 illustrates a surfboard indicated generally by the reference numeral 30 comprising an elongate body or hull 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 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 Figures 5 to 8 which is mounted substantially centrally between the two 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 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, 58 within a fin box on the body 32 of the board 30. The fin box is a commercially available product is built into the board by the board manufacturers during manufacture thereof.

The projections 52, 54 are clamped to the body 32 by means of a clamping arrangement which clamps them in the sockets 56, 58 in accordance with known techniques. In the illustrated embodiment, the surfboard manoeuvring device 10 is releasably mounted, e.g., 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 and be replaced with another surfboard manoeuvring device 10, e.g., of a different size and having different operational properties.

Figure 17 illustrates a surfboard that is a variation on the surfboard described above with reference to Figure 9.

In Figure 17, the mounting formation is positioned forward on the board relative to that that in Figure 9. This has the consequence or follow on effect that the fin of the device is positioned in substantially the same position that one would expect for as tri fin thruster fin arrangement. Further, the elongate member travels close to the bottom of the board parallel to the surface of the board and the fin of the device is in a very similar vertical position to the fin of the prior art thruster. Thus, this arrangement mimics the tri fin thruster fin arrangement and overall, the board visually resembles in a broad sense a regular surfboard with a widely used tri fin arrangement. The device when used on a surfboard in a broad sense facilitates the same surfing manoeuvres as those carried out with a thruster. However, it does it better than the prior art thruster for the reasons described in this specification.

If the position of the fin of the device along the length of the board is to be set as described immediately above, then the way to accommodate different lengths of elongate member is to move the axial position of the mounting formation on the board. If, for example, a longer elongate member was desired to be used on the board of Figure 17, then the mounting formation would be moved forward on the board to keep the fin of the device in substantially the same position.

In use, the surfboard manoeuvring device 10 is mounted on a surfboard 30 in the manner shown in Figure 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 formations 56, 58 in the body 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, the flexing of the elongate member 12 of the device increases the power of the surfboard 30 as it travels through the water and also enables the surfer to have more control of its movement through the water.

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

In Figure 10, the device 10 has a shorter elongate member 12 than the elongate member in Figures 5 to 8. As shown in the drawing, the device 10 terminates short of the rear end 38 of the board 32. The effect of this change on the operation of the board will be a stiffer feel to the user and good projection.

In Figure 11, the device 10 has a longer elongate member than the elongate member of the device 10 in Figures 5 to 8. In particular in Figure 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 member will impart good directional projection to a short surf craft fitted with the device. A relatively more flexible member will impart more turning ability.

Figure 12 is a schematic side view of a surfboard fitted with a surfboard manoeuvring device in in accordance with another embodiment of the invention. As this embodiment has many similarities to the earlier embodiment described above, the same reference numerals will be used to refer to the same components unless otherwise indicated. Further, the following description will focus on the difference between this embodiment and the earlier embodiments.

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

Figure 13 is a schematic side view of a surfboard fitted with a surfboard manoeuvring device in in accordance with yet another embodiment of the invention. As this embodiment has many similarities to the earlier embodiment described above, the same reference numerals will be used to refer to the same components unless otherwise indicated. Further, the following description will focus on the difference between this embodiment and the earlier embodiments. In the Figure 13 embodiment, the surf craft manoeuvring device is mounted to the rear end of the body of the surfboard. The body of the surfboard may have a recess within which a mounting formation on the device 10 is received.

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

In Figure 14, the device is mounted to an underside or lower surface of the surfboard towards the rear end thereof. The device has a fin having bearing surfaces extending in a substantially horizontal direction whereas the fin of the earlier embodiments extends in a vertical direction. The bearing surfaces extend laterally away from each side of the elongate member or flex boom.

The elongate member 12 turns down towards its end that leads into the fin 20. This positions the fin 20 a suitable distance beneath the surface of the water so as to be able to apply a force to the water passing over an upper surface of the fin without leaving the water. The effect of this different fin design on the operation of the board will allow the user to propel the surf craft forward by a rocking up and down leg driving motion known in surfing as leg pumping.

Figure 16 shows the watercraft manoeuvring device mounted to a windsurfer. In the drawing, the windsurfer will be referred to generally by the numeral 50. The windsurfer 50 includes a windsurfer body 52 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 50 towards the rear of the body 52 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 fins angle of attack to the water flow. The hull of a wind surfer is 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 Figures 1 to 4, can be constructed to have two foundation axes. They have a vertical mast axis extending perpendicularly away from the board and a horizontal boom axis extending rearward from the vertical mast axis. A long leading edge complements the vertical mast before transitioning into the horizontal boom. In all prior art fins, both the mast and the boom are bearing surfaces that bear against the water through which the board is passing. Further, all prior art fins have a base or foot that is fixed direct 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 surf craft body, e.g., hull. The elongate member or stanchion presents no bearing surface. Rather, the stanchion has a fin having a bearing surface at the far end thereof which moves with the stanchion and is not directly fixed to the board.

The surf craft manoeuvring device, by means of the elongate member or connecting stanchion, enables the fin to auto adjust its angle. 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 fin will adjust to the angle of least resistance through the water and this feature enables the surfboard to turn smoothly.

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

An advantage of the surfboard described above with reference to Figures 5 to 9 is that it provides a surfer with increased manoeuvrability and use of power when surfing a wave. It has the potential to provide a more exciting surfing experience than with 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 arrangement described in this disclosure 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 which can cause the surfboard to stall.

The device can be used in combination with two side fins and together they resemble the arrangement of the prior art thruster fin on a surfboard. That is, the three fins are positioned in broadly the same relative position to each other and the board when the manoeuvring device is used. The mounting formation is positioned forward on the board than the mounting formation of a socket for a thruster fin arrangement. This enables the actual fin on the device to be positioned in the same relative position as it would on a thruster fin arrangement. Additionally, the elongate member extends parallel to the surface of the craft so that the height of the fin at the end of elongate member relative to the body is similar to the height of the central fin on a thruster fin 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 for 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 (17)

CLAIMS:

1. A watercraft manoeuvring device for mounting on a watercraft, the watercraft manoeuvring device comprising: an elongate member having a mounting end and an opposed fin end that is spaced from the mounting end; a mounting formation at the mounting end of the elongate member for mounting on the watercraft; and a fin on the fin end of the elongate member having a bearing surface for interacting with the water through which the watercraft travels, wherein the elongate member is flexible such that it can flex when the fin is subjected to forces when it travels through the water.

2. A watercraft manoeuvring device according to claim 1, wherein the elongate member is resiliently flexible and flexes in response to hydrodynamic forces as it travels through the water, whereby the fin on the fine end of the elongate member is able to adjust its orientation in response to the forces.

3. A watercraft manoeuvring device according to any one of claims 1 to 3, wherein the elongate member has a circular cylindrical, elliptical or ovoid cross-sectional configuration.

4. A watercraft manoeuvring device according to any one of claims 1 to 3, wherein the elongate member has a length of 1mm to 1200mm.

5. A watercraft manoeuvring device according to any one of claims 1 to 3, wherein the elongate member has a length of 30mm to 100mm.

6. A watercraft manoeuvring device according to any one of claims 1 to 3, wherein the elongate member has a diameter of not more than 30mm so as to present a small surface area to the fluid through which it moves.

7. A watercraft manoeuvring device according to any one of claims 1 to 3, wherein the elongate member is configured to extend parallel to a lower surface of the watercraft on which it is mounted.

8. A watercraft manoeuvring device according to any one of claims 1 to 4, wherein the mounting formation has a low profile to streamline water flow over the mounting formation and the mounting formation is configured to be releasably mounted on the watercraft.

9. A watercraft manoeuvring device according to any one of claims 1 to 4, wherein the mounting formation, the elongate member and the fin are integrally formed of a polymeric material that is able to resiliently flex in use.

10. A watercraft for travelling across the surface of water, the watercraft comprising: an elongate body having an operatively upper surface for carrying a surfboard rider and an operatively lower surface for facing down into the water, and a watercraft manoeuvring device as defined in any one of claims 1 to 9, mounted on the elongate body for assisting a user to manoeuvre the watercraft through the water.

11. A watercraft according to claim 10, wherein the watercraft is a surfboard.

12. A watercraft according to claim 10 or claim 11, wherein the watercraft manoeuvring device is mounted on an operatively lower surface of the elongate body.

13. A watercraft according to any one of claims 10 to 12, wherein the elongate member extends parallel to the operatively lower surface of the watercraft and the fin on the device is positioned forward of a rear end of elongate body.

14. A watercraft according to any one of claims 10 to 13, wherein the elongate member extends parallel to the operatively lower surface of the watercraft at a distance of not more than 50mm below the operatively lower surface.

15. A watercraft according to claim 10, further includes two side fins mounted on the operatively lower surface of the elongate body and the fin on the watercraft manoeuvring device is centrally positioned on the elongate body a short distance forward of the side fins.

16. A surfboard for surfing water waves, the surfboard comprising: an elongate body having a nose and a tail and an operatively upper deck for carrying a surfboard rider and a bottom surface for facing down into the water, and a watercraft manoeuvring device as defined in any one of claims 1 to 9, mounted on the elongate body for assisting a user to manoeuvre the watercraft through the water.

17. A surfboard for surfing water waves according to claim 15, further including two side fins mounted on the bottom surface of the elongate body and wherein the fin on the watercraft manoeuvring device is centrally positioned on the elongate body distance forward of the side fins, so the side fins and the fin of the device form a tri-fin thruster arrangement.

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Figure 2 Figure 1

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Figure 3

Figure 4