AU707856B3 - Fin assembly - Google Patents

Description

FIN ASSEMBLY This invention relates to a fin assembly. This invention relates particularly to a fin assembly which is readily detachable from a surfboard.

This invention relates particularly to fin assemblies for surfboards and it will be convenient to hereinafter describe the invention with reference to this example application. However it is to be clearly understood that the invention has broader application. For example it extends to other water craft such as yachts, paddle skis and surf skis.

Surf boards comprise broadly a body having a core of buoyant material, an upper ride surface for supporting a surfer and a lower water surface which is received in the water. One or more fins are mounted on the lower surface thereof. Traditionally the fins have been permanently mounted to the body by being glassed onto the body. With this technique layers of fibreglass are mounted over the fin such that they extend downwardly over the fin and onto the body.

The disadvantage of permanently mounting a fin to a surfboard is that it cannot be easily removed and replaced when the fin is damaged. Further the fin cannot be easily removed from the board and replaced with another fin having different performance properties to enable experimentation with different fin types to occur. Further when transporting surfboards, the fin is relatively ungainly and consumes a large amount of space. Accordingly it would be advantageous in such situations to be able to remove the fin from the body of the board.

A removable fin assembly has been developed which is described in Australian patent 665804. This fin assembly comprises a fin having two thin rectangular tabs projecting outwardly from the base of the fin. Each such tab is received within a socket of a disc-like plug mounted in the lower surface of the body of the surfboard. The fin tabs are releasibly locked in the plug by means of opposed fastening elements such as grub screws which clamp the tab.

However this assembly has limited strength.

This fin assembly also has other shortcomings. For example this fin assembly requires precision work for it to be mounted on the body of the surfboard. This is because the two spaced plugs have to be spaced a precise distance apart to enable them to mate with the two fin attachment elements. In addition the number of grub screws used ie four per fin means that it is very time consuming to mount a fin to the board. Very often a surfer or a manufacturer will wish to mount a fin to the board in as short a time as possible.

A further feature of the fin assembly is a resin plug which extends from the bottom of the body attachment element through the core of the body to the upper ride surface of the surfboard. This resin plug provides some support for the fin attachment element to assist in mounting it in stable fashion on the body of the surfboard. However after use this resin plug tends to pop through the fibreglass coating on the ride surface of the surfboard. This is unsightly and also has the potential to cause water leakage into the inner core of the board.

Further shards of sharp glass are often present on the ride surface of the board and this clearly has the potential to cause a nasty cut or gash.

It would therefore be advantageous if an improved fin assembly which enabled the removable detachment of a fin to a body of a surfboard could be devised.

According to one aspect of this invention there is provided a fin assembly for use on a surfboard including: a fin including a fin body and a fin attachment element, the fin body having a base and a tip and defining two major surfaces extending from the base to the tip, and the fin attachment element projecting outwardly away from the base of the fin body and having a plurality of lateral formations projecting laterally outwardly transverse to the major surfaces of the fin body; and a body attachment element for permanently mounting on the body of a surfboard, the body attachment element defining a socket complementary to said fin attachment element including a plurality of lateral socket formations for receiving said lateral formations on said fin attachment elements, the body attachment element defining an inclined passageway extending from an outer surface of the body attachment element to a said lateral formation in the socket; and a fastening element received in said passage for positively fixing the fin attachment element to the body attachment element.

Thus the body attachment element defines an inclined passageway from a top surface thereof to a point within the socket spaced beneath the top surface within which the fastening element is received, and the fastening element is passed through said passageway to engage said lateral formation.

Preferably the fin attachment element has at least two. axially spaced said lateral formations.

Preferably each fin attachment element has two cruciforms axially spaced from each other and said lateral formations are formed by the lateral arms of each cruciform, and said cruciforms and complementary socket are inclined at an angle to the vertical as they extend away from respectively the base of the fin and the outer surface of the body attachment element so as to enhance the strength of the attachment of the fin to the body attachment element by creating an underpinning effect, and a said lateral formation on the fin attachment element includes a recess for receiving an end of the fastening element thereby to enhance the attachment of the fin to the body attachment element.

The engagement of the fastening element with the recess serves to actually latch or lock the fastening element to the fin and body attachment element which is substantially more than frictional or clamping engagement.

Advantageously the fin attachment element has a substantially linear central portion intermediate the two cruciforms. Typically the cruciforms extend deeper than the central portion.

In one embodiment there are two said fastening elements, one at each said end section. In another embodiment there is only one fastening element located at one of the end sections. In one embodiment the fastening element is a grub screw. In another embodiment the fastening element is a locking pin.

Typically the cruciforms are inclined either forwardly, rearwardly, sidewardly or a combination thereof to the vertical, such that when the fin attachment element is inserted into the body attachment element it is underpinned by the body attachment element.

Preferably the body attachment element overall has a dumb bell or dog bone configuration. Advantageously the body attachment element has an outer surface of complex shape, eg a sharp zig-zag shape, to increase the area of the attachment element in contact with the core of the surfboard body.

A fin assembly in accordance with this invention may manifest itself in a variety of forms. It will be convenient to hereinafter describe in detail several preferred embodiments of the invention with reference to the accompanying drawings.

It is to be clearly understood however that the specific nature of this description does not supercede the generality of the preceding statements. In the drawings: FIG. 1 is a three dimensional view of a fin assembly in accordance with a first embodiment of the invention; FIG. 2 is a three dimensional view of a body attachment element for the fin assembly of FIG. 1; FIG. 3 is a three dimensional view of the body attachment element of FIG. 2 mounted on a surfboard; FIG. 4 is a sectional plan view of the fin assembly of FIG. 1, section through IV-IV; FIG. 5 is a sectional front view of the fin assembly of FIG. 1, section through V-V; FIG. 6 is an exploded front view of a fin assembly in accordance with a second embodiment of the invention; FIG. 7 is a schematic three dimensional view from one side of a body attachment element for the fin assembly of FIG. 6; FIG. 8 is a schematic three dimensional view from the other side, of the body attachment element of FIG. 7; FIG. 9 is a schematic top plan view of the body attachment element of FIG. 7; FIG. 10 is a sectional front view of the body attachment element of FIG.

7; FIG. 11 is a bottom three dimensional view of the body attachment element of FIG. 7; FIG. 12 is a sectional front view of part of the fin assembly of FIG. 6 showing attachment by means of a grub screw; FIG. 13 is a sectional front view of part of the fin assembly of FIG. 6 showing attachment by means of a locking pin; FIG. 14 is a front and bottom view of a fin for a fin assembly which is a variation on the fin assembly shown in FIG. 6; FIG. 15 is a sectional front view of the fin assembly of FIG. 14 showing attachment by means of a grub screw; and FIG. 16 is a sectional front view of the fin assembly of FIG. 14 showing attachment by means of a locking pin.

In FIG. 1 reference numeral refers generally to a fin assembly. The fin assembly 1 comprises broadly a body attachment element 2 and a fin 3.

The body attachment element 2 comprises an elongate dog bone shaped housing 5 defining two spaced sockets 6 and 7. Each of the sockets 6 and 7 has a cruciform configuration with four arms projecting away from the centre of the cruciform substantially perpendicularly to each other. The lateral arms 8 and 9 and 10 and 11 project outwardly proud of the major surface of the fin 3 and are important structural features.

The fin 3 includes a fin body 30 and a pair of fin attachment elements 40 and 41. The body 30 extends outwardly away from a base 31 positioned adjacent the lower water surface 32 of the body of a surf board to a rounded tip 34 remote from the surface 32. The leading edge 35 of the fin 3 is important in determining the performance characteristics of any particular fin 3.

FIG. 2 shows the body attachment element 2 prior to it being fitted to a surf board.

The housing 5 of the element 2 comprises a bottom 14, a side wall 15 and a top 16. Associated with each cruciform socket 6 and 7 is a passageway angled down from the top 16 of the element 2 to the interior of the socket 6 or 7. Each passageway 25 is threaded to receive a threaded fastening element therein such as a grub screw shown as 48 and 49. The passageway 25 is positioned such that the screw 48 or 49 extends substantially parallel to the longitudinal axis of the element 2 and projects into a lateral arm 8 or 9 of the socket 6 or arm 10 or 11 of the socket 7.

The walls of the sockets 6 and 7 taper outwardly downwardly into the socket.

This feature which will be described in more detail below assists in the secure fixing of the fin to the attachment element 2.

The side wall 15 is multi-faceted as illustrated in the drawings. This feature helps resist movement and particularly rotation of the element 2 in the body of a surfboard when lateral and shear forces are applied to the element 2. A horizontally extending groove 21 is recessed in the side wall 15 of the housing about mid-way up the height of the wall 15. This groove 21 assists in the flow of resin in and around the element 2 when it is mounted in a surfboard.

It therefore performs an important function when fixing the element 2 to the surfboard. However when the element 2 has been inserted in the board its function has been completed.

The element 2 includes mounting formations 28 and 29 extending outwardly from each end of the element 2 for suitably positioning the element 2 on the surface 32 of a surfboard. The mounting formations 28 and 29 locate the element 2 at the appropriate height relative to the surrounding surface 32 of the surfboard body. The element 2 also has a ridge 23 projecting upwardly proud of the top 16 thereof around the peripheral edge of the element 2.

FIG. 3 shows the element 2 mounted in a surfboard body. The mounting formations 28 and 29 and the peripheral ridge 23 have been sanded off in the mounting process such that the top 16 of the element 2 is flush with the surface of the body 32.

Turning now back to the fin 3 in FIG. 1, the fin attachment elements 40 and 41 in the form of cruciforms project outwardly away from the base 31 of the fin 3.

Naturally the attachment elements 40 and 41 are of complementary size and shape to the sockets 6 and 7 in the element 3 such that they are received snugly therein. Each cruciform 40, 41 comprise four arms projecting outwardly away from a central point perpendicular to each other. Of particular importance are the lateral arms 43 and 44 and 45 and 46 projecting perpendicularly outwardly away from the major surfaces of the fin 3. The remaining two arms of each formation are substantially in line with the fin, ie axially extending.

In use the fin attachment elements 40 and 41 are inserted in the sockets 6 and 7 so that the base 31 of the fin 3 abuts the top 16 of the element 2. The grub screws 48 and 49 are screwed down into the passageways 25 until they wedge tightly against the adjacent lateral arms 43 and 44 of the cruciform fin elements and 41.

The grub screws 48 and 49 are on opposite sides of the fin 3, and tend to rotate the cruciform elements 40 and 41. This wedges them under the inclined wall of the sockets described above creating an underpinning effect. Further the rotation of the elements 40 and 41 also increases the frictional engagement of the elements 40 and 41 with the body attachment element 2. The rotation of the elements is shown clearly in FIG. 4 and the underpinning effect created by the tapered wall of the socket is shown in FIG. FIG. 6 illustrates a fin assembly 1 in accordance with a second embodiment.

The fin assembly is functionally and structurally similar to the fin assembly of FIG. 1 and unless otherwise indicated the same reference numerals will be used to refer to the same components.

In FIG. 6 the fin 3 has a fin body 50 and a single fin attachment element 51.

The attachment element 51 comprises a linear central section 54 and cruciform shaped end sections 52 and 53 at each end of the central section 54.

The end sections 52 and 53 are sloped backwardly away from the leading edge 35 of the fin 3 at an angle of approximately 200 to the vertical as shown in the drawings particularly FIG. 10. A notch or recess 55 is defined in the lateral formation or lateral arm 43 of the rear cruciform end section 52. This recess 55 is for receiving the leading edge of a fastening element, eg a grub screw. The interaction of the fastening element with the notch 55 is described in more detail below.

Like the fin 3, the body attachment element 2 has a single socket complementary to the fin attachment element 51 of the fin 3. That is the socket 60 has a linear central section 61 and cruciform socket formations 62 and 63 at each end of the central section 61. The cruciform socket formations 62 and 63 have respectively two lateral arms 66, 67 and 68, 69 and two axially extending arms.

An inclined passageway 65 is defined in the housing 5 from the top 16 thereof through to a lateral arm 68 or 69 of the end section 63 in much the same way as the passageway 25 in FIG. 1. A fastening element is passed through the passageway 65 to anchor the fin attachment element 50 to the body attachment element 60. In one form the fastening element is a locking pin which is received in the notch or recess 55 in the lateral arm of the fin attachment element. This locking pin 70 is shown clearly in FIG. 13. The locking pin comprises a cylindrical shank 71 with a flexible cover 72 at one end thereof. In another form the fastening element 48 is a grub screw 75 which engages a complementary screw thread defined in the passageway of the housing and which is also received in the notch 55 in the fin attachment element. The grub screw is illustrated in FIG. 12.

FIGS. 7 to 11 illustrate the body attachment element 2 in more detail. It includes two mounting formations 28 and 29 projecting laterally outwardly away from each end section thereof. The nature of the mounting formations 28 and 29 is described in more detail above with reference to the first embodiment illustrated in FIGS. 1 to 5. While the mounting formations in the first embodiment are axially rather than transversely extending their nature and function is substantially the same.

The side wall 15 of the housing 5 is complex in the sense that it is in the form of a sharp zig-zag. The purpose of this feature is to provide a greater surface area of housing 5 which is an adhesive contact with a buoyant core of the surfboard. This enhances the attachment of the body attachment element 2 to the buoyant core which is obviously important for the successful functioning of a fin assembly.

The top 16 of the housing adjacent the passageway 15 has a shallow surface recess 81 and a clip formation 82 for locating and attaching a locking pin 70 to the element.

FIGS. 14 to 16 illustrate a variation of the second embodiment illustrated in FIGS. 6 to 13.

The major difference between the two embodiments is that in FIG. 14 the fin attachment element 51 slopes forwardly relative to the fin body 50 instead of backwardly as in FIG. 6. A flow on effect of this is that the fastening element, be it grub screw 75 or locking pin 70 and associated passageway 65 are located proximate to the leading edge 35 of the fin 3 rather than remote from it. It would be readily understood by a person skilled in the art that the steeper the angle of inclination of fastening element to fin attachment element the greater will be the component of force urging against the fin attachment element.

FIGS. 15 and 16 show the attachment of the fin to the body attachment element 2 by means of both grub screws 75 and locking pins 70. The structure of the fin 3 in FIG. 13 is basically the same as that in FIG. 6.

Other differences of detail are that the body attachment element is longer than the fin and the head 72 of the locking pin 70 is not received in a recess in the body attachment element 2.

In another variation of the FIG. 6 embodiment which has not been illustrated, the fin attachment element projects perpendicularly out from the base 31 of the fin 3. In this way the fin 3 can be displaced directly towards and into the body attachment element 2 without any need for pivoting in much the same way as the FIG. 1 embodiment. This obviously eases installation of the fin although the fin assembly does not have the enhanced strength derived from the underpinning effect.

In yet another variation of the FIG. 6 embodiment which has not been illustrated, the fin assembly has two locking pins in the form of grub screws or locking pins 70 spaced from each other, ie disposed towards each end of the fin 3. Typically these locking pins would engage a lateral arm on each of the cruciform end sections 52 and 53 of the fin attachment element 51.

An advantage of the fin assemblies described in detail with reference to FIGS.

6 to 13 is that it is easy to mount on a surfboard. By virtue of the fact that there is only a single body attachment element to position on the board, the precise position of the element is not too critical although it must obviously be broadly axially extending. The fin attachment element will always be able to fit into the socket of the body attachment element. However with the prior art fin assembly which has two separate and discrete body attachment elements, the spacing of the body attachment elements on the board is absolutely critical to successfully fit the assembly. This is a difficult and precise operation to perform.

Further in the applicant=s FIG. 6 fin assembly, there is only one fastening element instead of the four for the prior art fin assembly. In addition locking pins are easier to work with because they do not require a hex nut or screw driver as do the grub screws. This is particularly so for surfers on the beach.

A yet further advantage of the fin assembly described is that the body attachment element does not require a resin plug beneath the body attachment element. Its size and configuration enable it to be mounted to the core of the surfboard body without such a resin plug.

A further advantage is that of the fin assembly is that it is strong. The lateral arms of the cruciform end sections have the effect of strengthening the fin attachment element. In addition the inclination of the fin attachment elements and complementary socket create an underpinning effect which serves to strengthen the overall fin assembly.

12 It will of course be realised that the above has been given only by way of illustrative example of the invention and that 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 herein set forth.

Claims (3)

1. A fin assembly for use on a surfboard, including: a fin including a fin body and a fin attachment element, the fin body having a base and a tip and defining two major surfaces extending from the base to the tip, and the fin attachment element projecting outwardly away from the base of the fin body and having a plurality of lateral formations projecting laterally outwardly transverse to the major surfaces of the fin body; and a body attachment element for permanently mounting on the body of a surfboard, the body attachment element defining a socket complementary to said fin attachment element including a plurality of lateral socket formations for receiving said lateral formations on said fin attachment element, the body attachment element defining an inclined passageway extending in a substantially longitudinal direction from an outer surface thereof into said socket; and a fastening element received in said passageway for anchoring said fin attachment element to the body attachment element.

2. A fin assembly according to claim 1, wherein the fin attachment element has two cruciforms axially spaced from each other and said lateral formations are formed by the lateral arms of each cruciform and wherein said cruciforms and complementary socket formations are inclined at an angle to the vertical as they extend away from respectively the base of the fin and the outer surface of the body attachment element so as to enhance the strength of the attachment of the fin to the body attachment element by creating an underpinning effect, and wherein a said lateral formation on the fin attachment element includes a recess for receiving an end of the fastening element thereby to enhance the attachment of the fin to the body attachment element. 14

3. A fin assembly substantially as herein described with reference to FIGS. 6 to 13. DATED THIS Seventeenth OF May 1999. PAT-TECH PTY LTD BY PIZZEYS PATENT AND TRADE MARK ATTORNEYS