Fin box

The present invention relates to a fin box adapted to be fitted to a watercraft and to receive a fin having a base. The fin box includes an elongate receiving portion having a length. The base is adapted to be inserted into the receiving portion substantially laterally. The fin during insertion into the receiving portion is disposed at a lower than 90 degree angle to the receiving portion.

TECHNICAL FIELD

The present, invention relates broadly to watercraft and relates particularly though not exclusively to a fin box for surfboards.

BACKGROUND ART

Surfboards typically have either one large fin or three small fins. In the case of a single fin surfboard, the fin is usually fixed on the underside of the board towards its tail along the centre line. A three-fin surfboard usually includes a fin attached to the underside of the rear of the board on its centre line, and the other two side fins placed symmetrically towards the outside edges of the board. The two side fins are usually raked outwards by around 4 degrees compared to the centre fin.

Surfboard fins are either permanently fixed to a surfboard by means of fibreglass resin, or are removable, using a variety of fixing systems.

Fixed fins are generally stronger and stiffer than removable fins and are expected is to give better performance when surfing. Fixed fins are more expensive to install and replace if damaged. They are also more cumbersome to transport.

By contrast, removable fins are secured to a surfboard, generally via a fin box, which is typically permanently fixed to the surfboard by a polyester resin. Prior art removable fins have an inferior performance compared to fixed fins due to the less rigid mounting. However, removable fins are advantageous in that 1) they allow a surfer to choose a specific type of fin to suit his or her own style of surfing; 2) fins can be changed for different conditions and may easily be replaced if broken; and 3) the surfboard itself is less susceptible to damage than the fin. As such, when the fin breaks, it is not uncommon that the surfboard remains intact. Some fins in the marketplace such as those disclosed in U.S. Pat. No. 7,025,645 and U.S. Pat. No. 5,567,190 can be replaced and adjusted to suit different conditions for better performance but this requires complex re-positioning of the fin.

One of the main deficiencies of removable fins is the susceptibility of the fin box to flexing in the surfboard. This means that the fin is likely to move with the flexing box, thereby impairing the performance of the fin. To address this problem, some fin boxes in the marketplace are secured to the hard top face of the surfboard either by means of a screw fixing or an adhesive fixing to the inside face of the top surface.

The total weight of a surfboard is also critical. A surfboard should preferably be kept as light as possible. Generally speaking, the lighter the box and less resin used for installation in the board, the better the surfboard performs.

The ease of installation of the fin box into the surfboard is of critical importance to a fin system. If the fin box is too difficult or takes too long to install, it will not be welcomed by surfboard shapers. Ease and speed of installation are therefore believed to have a huge influence on the sale of surfboard fin systems.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a fin box adapted to be fitted to a watercraft and to receive a fin having a base, the fin box including an elongate receiving portion having a length, the base being adapted to be inserted into the receiving portion substantially laterally, the fin during insertion into the receiving portion being disposed at a lower than 90 degree angle to the receiving portion.

Preferably, the receiving portion is longer than the base which is movable in use between two or more positions with respect to the receiving portion.

Preferably, the fin box includes one or more retaining means adapted to retain the fin within the fin box. More preferably, the retaining means includes at least one protrusion adapted to engage at least part of the base. The protrusion may take the form of an elongate bar. The retaining means may be located in proximity to an upper edge of the receiving portion, thereby allowing the receiving portion to have a minimal depth.

The base of the fin is preferred to be shaped so as to facilitate insertion thereof into the receiving portion substantially from one side thereof. The base preferably has at least one slot on each of the opposing sides. At least a portion of each slot on each side may be adapted to engage the protrusion. More preferably, there are two slots on each of the opposing sides, the two slots being divided by a section. Even more preferably, the retaining means also include at least one impediment on each side of the base, the impediment being adapted to in use engage the section so as to prevent the fin from sliding longitudinally. Another portion of each slot is preferred to include an engagement means adapted to in use be engaged by one or more securing means. The securing means may be movably connectable to the receiving portion, the securing means adapted to lock the fin in one of the positions.

In one embodiment, the base includes one or more, engagement means forming part of one or more of the slots, respectively. It is preferred that the or each engagement means is a shoulder to which the securing means in use abut. Preferably the shoulder is tilted towards the securing means to facilitate abutment.

Optionally, the engagement means is connected to the base via a frangible element or an area of weakness adapted to fracture or shear at a predetermined load, for example when the fin hits a rock, thereby enabling the fin to break away from the fin box. This is advantageous in that damage to the fin box and watercraft can be minimised in the event of an accident. The frangible element or area of weakness may be connected to or form an integral part of the base. In the most preferred embodiment, at least part of the engagement means, is made of or coated with a harder material than that of the base or fin.

In an alternative embodiment, the fin is adapted to be received in a single position within the fin box. In other words, the fin in such an embodiment is not movable within the fin box. Both the impediments on the fin box and the sections dividing the slots become superfluous and hence may be omitted. In this embodiment, the base includes one or more orifices into which engaging means in the form of tilted shoulders extend. Conveniently, the shoulders are tilted towards one another. Preferably, the securing means in the form of grub screws go through the respective through apertures angularly to abut the respective tilted shoulders.

In one embodiment, the securing means include one or more (preferably at least two) screws adapted to engage the base. The receiving portion may have or be associated with a through aperture for receipt of the, or each, securing means.

Each securing means is preferred to be configured so as to be at least partially movable from an unlocked position to a locked position for preventing any undesired movement of the fin. The securing means may include a biasing means such as a cam with a rotational axis, and a member which is rotatable about the axis to engage with a slot in the fin, so as to prevent undesired such as vertical movement of the fin when locked in place. The cam may be configured such that it is manually rotatable by a simple tool.

In a preferred embodiment, the securing means is configured to enable installation and removal of the fin with minimal tools.

In another embodiment, the securing means includes a flexible or rotatable arm with a head designed to in use engage with the slot in the fin, so as to prevent vertical movement of the fin when locked in place. A biasing means such as a cam or lever, may be included to enable movement of the arm with or without a tool.

Preferably the fin box is configured to have a minimal depth so as to enable placement thereof at or adjacent the rear of the watercraft.

In a preferred embodiment an external surface of the receiving portion comprises a framework so configured as to facilitate positive/interlocking engagement thereof with an adhesive material for affixing the fin box to the watercraft. Conveniently the external surface includes guiding means for directing flow of the resin throughout the receiving portion during installation. Preferably the guiding means include channels provided throughout the wall of the receiving portion to enable thorough penetration of the resin so as to encapsulate selected portions of the framework.

In one embodiment, a removable infill part is placed in the receiving portion of the fin box prior to the attachment of the removable lid. This infill may be shaped such that part or all of its upper surface corresponds with the depth to which the layer of resin covering the fin box is desired to be sanded during installation. The infill is preferably made of a hard material, such as ceramic, which does not easily get worn away by the abrasive used for sanding the surfboard. The infill is preferably reusable. The upper surface of the infill may be shaped so as to allow the surface of the surfboard to be easily sanded to a curved profile from front to rear of the fin box.

Preferably the fin box includes a removable lid adapted to seal the receiving portion. Optionally the lid has one or more fastening means for securing the lid to the fin box. The fastening means may include one or more of the following: a threaded fastener, a quarter turn fastener, or a press or clip fit mechanism.

Optionally the infill is releasably attached to the removable lid. Conveniently the lid is removable in its entirety during sanding.

It is preferred that the lid includes one or more indicators adapted to assist in providing an indication of a thickness of the lid.

The fin box may include a positioning means forming an integral part of or removably attachable to the lid. The positioning means is preferred to be a plate adapted to facilitate angular adjustment of the fin box with respect to the watercraft. The plate may be removably attachable to the lid by fastening means such as a threaded fastener, a quarter turn fastener, or a press or clip fit mechanism.

Optionally the infill is configured such that the positioning means is removably attachable to the lid by fastening means such as a threaded fastener, a quarter turn fastener, or a press or clip fit mechanism.

In another embodiment of the fin box of the present invention, the retaining means are in the form of protrusions and may include one or more lugs extending from a is wall of the receiving portion. Most preferably, one or more pairs of retaining means are provided. In a preferred embodiment, the base includes a flange with one or more legs. Preferably each of the legs has a foot adapted for engagement with one or each pair of retaining means.

In this embodiment the receiving portion may include a circumferential shoulder defining a recess for accommodating the one or more legs.

In this embodiment, each securing means is configured so as to be at least partially movable from a suppressed position to a released position for impeding longitudinal movement of the fin. The securing means may include a head portion and a pair of arms, each of the arms having a return for engagement with the receiving portion. Preferably the pair of arms are located intermediate the shoulder and the flange of the base. More preferably the shoulder includes or is connected to a pair of props on which the pair of arms rest, respectively. The securing means may be adapted to be biased by the props to the released position.

The head portion may be adapted to impede movement of the flange of the base when the securing means is in the released position thereby facilitating locking of the fin in the receiving portion in a predetermined position.

Conveniently the fin box includes two securing means, one located at each end. In a preferred embodiment, when in use, one securing mean is in a suppressed position while the other securing means is in the released position. Preferably suppression of one securing means from the released position to the suppressed position enables longitudinal movement of the fin along the receiving portion.

In this embodiment, the securing means includes a member adapted to be releasably fixed onto a predetermined location of the circumferential shoulder via a fixture. Conveniently the fixture includes a screw. Preferably the member when in use is configured to abut the flange of the base thereby impeding it from moving. In a preferred embodiment the member is in the form of a quarter-moon-shaped plate.

Preferably the fin box is affixed to the watercraft by an adhesive material. The adhesive material may be a resin. The fin box may include a dam for receipt of the adhesive material. Preferably the dam surrounds the fin box conforming to the shape thereof. The dam may be integral with the fin box. Conveniently the dam is connected to the fin box via a plurality of struts. Preferably the dam is at least partially removed such that the fin box is flush with the watercraft when in use. In this embodiment, the dam may be at least partially removed by sanding during installation of the fin box.

Conveniently the fin box includes one or more location indicators to facilitate accurate positioning thereof. Preferably the receiving portion is symmetrical in shape. Even more preferably the receiving portion is adapted to receive fins for different purposes. Typically the fins include both side and centre fins. Most preferably the receiving portion is capable of receiving various fins retrofitted with an adaptor. The adaptor may vary in size so as to fit onto fins of different shapes and sizes.

Preferably the base includes a curvedly diverging contour so as to provide an adjoining region with a smooth transition from the body of the fin to the surface of the watercraft.

Optionally an underside of the fin is cored out to reduce the weight of the fin.

The fin may have a hollow cavity, thereby allowing inclusion of a stiffening element for control of the lateral stiffness of the fin. The stiffening element may be removable and replaceable with an element of a different stiffness. The stiffening element may be adapted to vary in stiffness. The stiffness may be adjusted by varying parameters such as the cross section of, and/or the stress in, the stiffening element. The stiffening element may also be configured to vary in stiffness by altering the second moment of area of the stiffening element.

In a preferred embodiment the fin box is configured to enable installation and removal of the fin with minimal tools.

Optionally the fin box is adapted to be received in a cavity provided in the watercraft. The fin box is preferred to be elongate in shape having elliptical or arcuate ends. Most preferably the fin box is made of a light but stiff material such as glass or carbon fibre reinforced polymer.

The watercraft herein referred to includes a surfboard.

According to another aspect of the present invention there is provided a fin having a body and a base adapted to be contiguously adjoined to a surface of a watercraft when in use, the base having a streamlined profile so as to minimise resistance to a current of water.

According to a further aspect of the present invention there is provided a method of manufacturing a surfboard having a fin box, the method including some or all of the steps of:(1) producing a surfboard blanks;(2) providing a cavity to receive the fin box;(3) inserting the fin box into the cavity;(4) covering the fin box with a layer of resin; and(5) sanding the layer of resin to be flush with the general surface of the surfboard.

Preferably the method includes one or more of the following steps:(6) inserting the infill into the receiving portion of the fin box being inside the cavity;(7) providing a lid for the fin box;(8) removing the cover after sanding; and(9) removing the infill.

BEST MODE OF CARRYING OUT THE INVENTION

For the ease of reference, common components in different embodiments of the present invention are given the same numeral.

As shown inFIGS. 1,2and3, there is a fin box1being fitted to a watercraft such as to the deck of a surfboard (not shown). The fin box1is elongate in shape having elliptical ends6. The fin box1in this embodiment is made of a stiff yet light material such as glass or carbon fibre reinforced polymer.

Referring toFIG. 4, the fin2is received within the fin box1which in turn is received in a cavity20provided in the watercraft. The fin box1includes a receiving portion10and securing means8. The receiving portion10is longer than a base4(refer back toFIGS. 1,2and3) of the fin2. The base4in the present embodiment is in the form of a flange. The securing means8are located on one side of the fin box1. The securing means8are for locking the fin2in a chosen longitudinal position in the receiving portion10.

As best shown inFIGS. 4 and 5and9, the fin box1includes retaining means in the form of elongate protrusions12extending from an internal side wall14of the receiving portion10. The elongate protrusions12engage part of the base4in the present embodiment. The fin box1also includes impediments17which are placed between the protrusions12on each side of the fin box1.

The receiving portion10has a through aperture28for receipt of a securing means which is in the form of a grub screw8. The through aperture28is designed such that it facilitates angular insertion of the grub screw8. The through aperture28is threaded on its internal bore allowing the grub screw8to be progressively driven towards the base4until it is stopped by the shoulder26. Shoulder26is partly made of a hard material, such as metal in this embodiment, and adjoins an element designed to shear at a predetermined load, thus enabling the fin base4to break free from the fin box1, minimising damage in the event of a severe impact.

Referring toFIG. 9, the width of the base4is indicated by A-A. The base4has an optimised width so as to enhance its stability when in engagement with the receiving portion10. The base4also has a minimal depth indicated by B-B so as to facilitate insertion thereof into the receiving portion10from one side (refer toFIGS. 6,7and8). The base4includes sections24on opposing sides thereof (refer toFIGS. 6 and 8). The sections24are placed so as to facilitate engagement with corresponding slots16in the receiving portion10in two or more discrete longitudinal positions. Slots22located on the opposing sides are adapted to mate with the respective elongate protrusions12. It should be noted the slots22are longer than the respective protrusions12, which means that the slots22are movable longitudinally along the length of the respective protrusions12. Each slot22includes an engagement means in the form of a shoulder26which in use is engaged by the grub screws (not shown) in the present embodiment, for securing the base4to the receiving portion10. In this embodiment, the shoulders26form part of the slots22, respectively. The shoulders26which form a portion of the respective slots22are planar surfaces tilted towards the grub screws to facilitate abutment. In this embodiment, each shoulder26is tilted towards the grub screws (or the direction from which the grub screws are inserted into the through apertures8. Each shoulder26is connected to the base4via a frangible element or an area of weakness (not visible) adapted to fracture at a predetermined load, for example when the fin hits a rock, thereby enabling the fin2to break away from the fin box1. This is advantageous in that damage to the fin box1and watercraft can be minimised in the event of an accident. The frangible element or area forms an integral part of the base. In the most preferred embodiment, at least part of the shoulders26is made of or coated with a harder material than that of the base4or fin2.

The elongate protrusions12are located in proximity to an upper edge18of the receiving portion10. This allows the receiving portion10to have the minimal depth (indicated by B-B) for stably supporting the base therein.

To operate this embodiment, the user must first determine where the fin2is to be located. A side of the base4is then inserted into the receiving portion10at the selected longitudinal location. As one side of the base4enters the receiving portion10, the protrusions12mate with the respective slots22. The section24is aligned with one of slots16, thereby restricting longitudinal movement of the base4within the receiving portion10. The other side of the base4is then dropped into the receiving portion10. Two grub screws8are driven into the through apertures28respectively until the ends of the grub screws8abut the shoulders26of the respective slots22. In this way, the pressure exerted by the grub screws8on the respective shoulders26firmly secures the base4within the receiving portion10at the selected location. If and when the user wants to shift the fin2forward or rearward, the grub screws8need to be unscrewed allowing the fin2to be removed and re-engaged in a desired longitudinal position (i.e. either forward or rearward of the initial position). Once the fin2is moved to the desired position, the grub screws8are re-applied as described above to secure the base4in place.

Although not readily visible fromFIG. 6, each shoulder26is connected to the base via a frangible element or an area of weakness adapted to fracture or shear at a predetermined load, for example when the fin hits a rock, thereby enabling the fin to break away from the fin box1. This is advantageous in that damage to the fin box and watercraft can be minimised in the event of an accident. The frangible element or area of weakness in this embodiment forms an integral part of the base4. Also, part of each shoulder26is coated with a harder material than that of the base4or fin2.

Referring toFIG. 6a, in this embodiment, the fin2is adapted to be received in a single position within the fin box1a. In other words, the fin2ais not movable within the fin box1a. As such, both the impediments17on the fin box1aand the sections24(refer toFIG. 6) dividing the slots22become redundant and hence are omitted. In fact, three slots22aare provided in the base4ain this embodiment. The base4aincludes two orifices27into which engaging means in the form of tilted shoulders26aextend. The shoulders26aare tilted towards one another. During installation, grub screws (not shown) go through the respective through apertures angularly to abut the respective tilted shoulders26a.

As best shown inFIG. 9, the base4is contiguously adjoined to the surface of the surfboard when in use. The base4has a streamlined profile so as to minimise resistance to a current of water. The base also has a currently diverging contour so as to provide an adjoining region30with a smooth transition from the body of the fin2to the surface of the surfboard. The adjoining region30may also be referred to as a fillet radius running around the base4of the fin2, so as to form a smooth blend from the surface of the fin2to the top surface of the sanded fin box1and the finished surface of the surfboard. The diverging contour has the effect of decreasing turbulence in the flow of water around the base4of the fin2thereby making the surfboard faster and more responsive. By varying the geometry of the blend between the fin2and surfboard, the characteristics of the fin2can be varied to suit different conditions and riding styles.

As shown inFIG. 10, the underside of the fin2may be cored out to create a hollow cavity32thereby reducing the weight of the fin2. The cavity32may vary in length, width and depth. The cavity32in a preferred embodiment allows introduction of a replaceable or variable stiffening element for the control of the lateral stiffness of the fin.

As shown inFIG. 11, the stiffening element34in the present embodiment is replaceable. As such, other elements of varying stiffness may be used to alter the characteristics of the fin by removal of the existing element34, and replacement with another stiffer or more flexible one. In another embodiment, the stiffening element34is integral with or permanently installed in fin2, and consists of a component with variable lateral stiffness. In this embodiment, the stiffness may be varied by means of changing the cross section of the element by rotation or other means, by varying the internal stresses in the element or the fin itself, or by other appropriate means.

Turning now toFIG. 12, a removable lid36is provided to seal the receiving portion10. The lid36functions as a sacrificial cover which is snugly fitted into the fin box1. The lid is shaped complimentarily to the opening of the receiving portion such that once the lid is put in place, the fin box1becomes substantially fluid-proof. The lid36has fastening means (not shown) for securing the lid36to the fin box1. The fastening means in this embodiment comprises a press or clip fit mechanism but may take other forms such as threaded fasteners or quarter turn fasteners. The lid also has two tabs38for covering the respective holes provided for the two grub screws8.

As shown inFIG. 13, a sanding infill42is provided. The sanding infill42is placed in receiving portion10of fin box1prior to attachment of lid36. An upper surface44of sanding infill42matches the height to which the edges of fin box1are desired to be sanded. The upper surface44of the sanding infill may be substantially plane, cylindrical, or any compound shape as desired, and defines the final sanded surface of the surf craft adjacent to the fin box1. The sanding infill42may include means (not shown) means which facilitate attachment of the removable lid36and/or a positioning means in the form of a plate46(seeFIG. 14) to the infill42. The sanding infill42may also have cavities (not shown) to allow for its removal from the fin box after sanding is completed. The sanding infill may be solid or hollow.

In this embodiment, the sanding infill42is made of a material which is harder than the fin box1, and also than the resin used to secure the fin box1. Additionally, the sanding infill42is made of a material which does not cause sparks when it is abraded by a sanding disc. In the most preferred embodiment, the sanding infill42is made of or coated with a ceramic material, and is reusable.

Referring toFIG. 14, the plate46forms an integral part of or is removably attachable to the lid36. The plate46is used to facilitate angular adjustment of the fin box1with respect to the surfboard. The plate46is removably attachable to the lid36by a press or clip fit mechanism. Attachment however may also be effected by using fastening means such as threaded fastener(s)48or quarter turn fastener(s), or other suitable means.

In this embodiment, the lid36plays a key role in preventing resin from entering the fin box1when the fin box1is ‘glassed’ to the surfboard in the manufacturing process, eliminating the necessity for masking tapes. The sanding infill42in the present embodiment reduces the length of time required to sand away the resin covering the fin box1by eliminating the need to continually check the sanding depth, and by preventing over sanding.

The procedure involved in manufacturing a surfboard with the fin box1of the present invention will now be described. The first step is to shape a foam surfboard blank to a desired form. A cavity for each fin is then routed in the underside of the blank to receive the fin box1using a router jig. The foam blank is covered with a glass fibre mat and resin to provide a strong and rigid surface. The areas around the fin box1are left uncovered. The surface of the surfboard is sanded to provide a smooth finish. Sanding infill42is then placed in the receiving portion10of fin box1, and lid36is clipped into the fin box. The plate46is then attached to the lid36and/or sanding infill42, to provide a visual indication of the lateral angular orientation of the fin box1with respect to the surface of the surfboard. Also, the plate46provides a convenient handle for holding and manipulating the fin box1when it is being painted with resin for adhering into the cavity provided in the surfboard.

Turning toFIG. 14, once the fin box1is fixed into the surfboard, the plate46is removed. The plate46in the present embodiment is made of a material to which polyester resin does not adhere, for example, polyethylene, and is reusable. The fin box1is then ‘glassed over’ with a glass fibre mat and laminating resin resulting in a patch of fibre glass over the fin box1. The lid36and sanding infill42are kept in the fin box1at this stage. The resin covering the fin box is sanded back to be flush with the previously glassed surface of the surfboard. Upper surface44of sanding infill42now limits the depth to which the resin covering the fin box can be sanded, by dint of its superior hardness compared to the resin. The lid36in a preferred embodiment is completely sanded away. The sanding infill is then removed from the fin box by leverage. In an alternative embodiment, sanding infill42is not used. In this case, depth indicators40(refer toFIG. 12) are provided on the lid36to assist in determining the desired sanding depth. For instance, the edge of the fin box1may be sanded down substantially precisely by 1.25 mm. The lid36is then removed from the fin box1by leverage.

In both embodiments described above, the fin box is glued into the cavity in the foam blank and laminated to the underside surface of the surfboard by having glass fibre and resin over the flange of the fin box1. The glass fibre and resin hold the fin box securely in the surfboard. The surfboard is by this time ready for removable fins to be installed.

Referring now toFIGS. 15 and 16, another embodiment of the present invention is shown. In this embodiment, the fin box1is fitted to a watercraft such as to the deck of a surfboard (not shown). The fin box1is elongate in shape having arcuate ends50, and receives a fin2in a front or rear position. Referring toFIG. 18, the fin2is received within the fin box1which is in turn received in a cavity20provided in the watercraft. The fin box1includes a receiving portion10and securing means52(refer toFIG. 16). The receiving portion10is longer than the base4of the fin2. The base in the present embodiment is in the form of a flange. The securing means52is for locking the fin2in a chosen longitudinal position in the receiving portion10, and may be located at either end of the fin box1, depending on whether the fin is desired to be in the fore or aft position.

As best shown inFIGS. 17,18and19, the fin box1includes three pairs of retaining means in the form of lugs58extending from a wall60of the receiving portion10. The lugs58function to retain the fin2within the fin box1. Referring toFIG. 17, the base4also includes legs64. The receiving portion10includes a recess68for accommodating the legs64. The legs have feet62for engagement with the respective pairs of lugs58. During installation, the feet62are in engagement with the lugs58thereby preventing the fin2from becoming detached from the fin box1.

Referring now toFIGS. 15 to 19, the securing means includes a member52which covers a gap between the receiving portion10and the fin2after placement thereof. The member52is designed to be releasably fixed to receiving portion10by way of a fixture such as a screw56having a flat head in the present embodiment. During installation, the screw56passes through an opening54in the member52and engages threads70and72of the receiving portion10. The screw56moves downwards along the threads70or72until the flat head of the screw56firmly abuts the surface of the member52. Being in such a position, the member52is substantially flush with the base4of the fin2and prevents longitudinal movement of the fin2. In the most preferred embodiment, the member52is in the shape of a fingernail or quarter-moon being complementary to the ends of the base4of the fin2.

It can be appreciated that the member52may be disconnected from the threads70for engagement with the threads72(seeFIG. 19). As such, the member52is removable as well as movable from one end of the receiving portion10to the other. When the member52is not applied, the base4is shiftable towards one end or the other. In contrast, once the member52is locked in place to either of the threads70or72, the base4can no longer move longitudinally along the length of the fin box1. In the embodiment, the only tool that is required is a screw driver or Allen key to secure the member52to the threads70or72. The member52is therefore easy for a user to carry and apply when removing, installing, repositioning or exchanging a fin.

Referring toFIG. 19, the fin box1is affixed to the watercraft by an adhesive material. The adhesive material in this embodiment is a resin. The fin box includes a dam74for receipt of the adhesive material. The dam74surrounds the fin box1conforming to the shape thereof. In this embodiment, the dam74is integral with the fin box and the dam74is connected to the fin box via a plurality of struts76. The dam74includes a plurality of tabs78evenly distributed throughout the body of the fin box1. The dam74is partially removed such that there is no protrusion out of the watercraft. In this embodiment, the dam74is partially removed by sanding for practical as well as aesthetic purposes. As shown inFIGS. 15 and 16, after the dam74is removed, only the receiving portion10of the fin box1is left.

Referring toFIGS. 17 and 19, the receiving portion10has a round bottom with three windows80, which correspond to the three pairs of retaining means58respectively. The windows80are provided for ease of manufacturing, and are sealed prior to installation of the fin box in a surfboard.

Referring now toFIGS. 20 to 22, a further embodiment of the present invention is shown. As shown inFIGS. 21 and 22, two (instead of one) securing means82and84are provided. Each securing means is configured so as to be at least partially movable from a suppressed position to a released position for impeding longitudinal movement of the fin2. The receiving portion10includes a circumferential shoulder50defining the recess68for accommodating the legs on the base4of fin2(not shown).

The securing means in this embodiment includes a head portion86and a pair of arms88. Each of the pair of arms88includes a return90for engagement with the receiving portion10. The head portion86includes a step92such that the base4of is the fin2, once put in place, is flush with the elevated part of the head portion86. The pair of arms88are located intermediate the shoulder68(referFIG. 17) and the fin base4(ie. flange). The shoulder68includes a pair of props (invisible inFIG. 22) on which the pair of arms88rest, respectively. The securing means82and84in this embodiment are biased by the props to the released position when the base4is shifted to one end. As such, the head portion86impedes longitudinal movement of the base4when the securing means82or84is in the released position thereby facilitating locking of the fin2in a predetermined position. It is important to note that the fin box1of the present invention is configured to enable installation and removal of the fin without tools, particularly heavy-duty tools.

As can be seen inFIG. 22, the two securing means82and84are located at opposite ends of the fin box1. When in use, one securing mean is in a suppressed position while the other securing means is in an extended position. Suppression of one securing means from the extended position to the suppressed position enables longitudinal movement of the fin1along the receiving portion10. As such, the location of the fin1is moved from a rear (locked) position as shown inFIG. 20to a middle (unlocked) position as shown inFIG. 23, and thence to a front (locked) position.

Referring now toFIG. 21, the external surface of the fin box1has a framework94so configured as to facilitate positive and interlocking engagement thereof with the resin during installation of the fin box into a surf board. The external surface of the fin box1also includes guiding means for directing flow of the resin throughout the receiving portion during installation. The guiding means in the present embodiment are in the form of channels96and98and through apertures (not shown) provided throughout the wall of the fin box1to enable thorough penetration of the resin so as to encapsulate selected positions of the framework.

The receiving portion10of the embodiments described, are but need not be, substantially symmetrical in shape. Also, the receiving portion10is designed to receive different fins for different purposes. For instance, the receiving portion10in this embodiment can receive either a centre or a side fin.

Furthermore, the receiving portion10is capable of receiving various fins retrofitted with an adaptor (not shown). The adaptor may be adapted to mount onto a fin and vary in size so as to fit onto fins of different shapes and sizes. The adaptor and fin may be releasably connected by way of an interlocking mechanism or permanently fixed together.

Installation and operation of the fin box1of this embodiment of the present invention are now described. In order to install the fin box1, a predetermined volume of foam core is excavated from the underside of the watercraft creating a cavity. The fin box is then inserted into the cavity and a polyester resin poured into the space between the box and the foam. Once the resin has set, the protruding edges of the dam74are sanded flush with the surfboard. The strength of the joint between the fin box1and watercraft is critical as it determines the stiffness of the fin. Following placement of the fin box1, the fin2is then inserted into the receiving portion10of the fin box1. The legs of the base4should be lowered into the receiving portions in between the lugs58. Once the base4is set in place, it is slid longitudinally along the length of the receiving portion10until the rectangular feet62engage the corresponding lugs58.

In the embodiment shown inFIGS. 15 to 19, following placement of the fin2, the member52is screw fixed using one of the threads70or72. Repositioning of the fin2would involve the steps removing the member52, sliding the fin2to the opposite end of the receiving portion10, and screw fixing the member52using the other thread,72.

In the embodiment shown inFIGS. 20 to 23, as soon as the fin base is slid to one end of the receiving portion10, one of the securing means, for example82will automatically pop, up locking the fin2in position. When it is desired to mode the fin position, the securing means82which is in the raised position is depressed, allowing the fin base4to be slid to the other end of the fin box1. Once it has been moved to the new position, the securing means84at the opposite end pops up, preventing longitudinal movement of the fin2.

Now that preferred embodiments of the present invention have been described in some detail, it will be apparent to those skilled in the art that the fin box of the invention is capable of having one or more of the following advantages over the prior art:(i) building of a dam with modelling clay is no longer required for installation of the fin box;(ii) installation and removal of the fin from the fin box may be effected with minimal tools;(iii) the fin may be shifted and locked in position in a simple operation with minimal tools;(iv) the longitudinal position of the fin relative to the fin box may be easily varied;(v) the fin box may be located in the proximity of the shallow front or rear end of a watercraft;(vi) the overall stiffness and flexibility of the fin may be varied;(vii) provide a convenient way of preventing resin from flowing into the interior of the fin box;(viii) provide an indication of the lateral angular orientation of the fin box within the surfboard in manufacturing process;(ix) provide indicators to aid in establishing the correct depth of sanding during installation of the fin box;(x) provide a stiff and secure mounting system; for the base of the fin, particularly in the lateral direction;(xi) facilitate breaking off of the fin from the fin box on application of a predetermined lateral force;(xii) allow adjustment of the lateral stiffness of the fin; and(xiii) provide a contoured base with enhanced hydrodynamics.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. For example, the retaining means may take the form of a retractable latch or lock. The securing means and receiving portion may take another shape or form. All such variations and modifications are to be considered within the scope of the present invention the nature of which is to be determined from the foregoing description.

INDUSTRIAL APPLICABILITY

The fin box of the present invention is capable of facilitating insertion of a fin laterally from one side into a considerably shallow fin box being received within a surfboard. Also, the fin of the present invention can be movable within the fin box and offers enhanced hydrodynamics, which significantly improve the control and performance of the surfboard.