WO1995031366A1

WO1995031366A1 - A fin unit

Info

Publication number: WO1995031366A1
Application number: PCT/AU1995/000278
Authority: WO
Inventors: Robert John Waters
Original assignee: Robert John Waters
Priority date: 1994-05-17
Filing date: 1995-05-16
Publication date: 1995-11-23

Abstract

A fin unit (10) includes a fin (12) having a base (14) for mounting at an underside (15) of a surfcraft (11) (e.g. a surfboard). The base (14) has an integral projection (16) extending therefrom which is received for rotation and selective fastening in a receipt means (18). The receipt means (18) is in turn adapted for mounting in the underside (15) of the surfcraft (11).

Description

A FIN UNIT

TECHNICAL FIELD

The present invention relates to a fin unit for use on surfcraft such as surfboards, surfskis, kayaks, wind surfers, wave jumpers, boogie boards, knee boards, paddles etc. Particularly, though not exclusively, the invention relates to a fin that can be releasablv attached and rotated with respect to the surfcraft.

BACKGROUND ART

Fin systems are known that enable a fin to be releasably attached to the underside of surfcraft. They include the so called "fin box" unit. The fin box allows a fin to be retained and slidably mounted within a longitudinal channel box embedded in the underside of the surfcraft. Similar systems employ a plurality of retention formations embedded in the underside of the surfcraft into which corresponding lugs projecting from the fin are detachably retained. Some advantages of releasably mounting fins to surfcraft are that fins can be interchanged, replaced when broken, and in some known forms, shifted forwardly and rearwardly on the underside of the surfcraft to alter the performance of the craft.

DISCLOSURE OF INVENTION

In a first aspect, the present invention provides a fin unit for a surfcraft including: a fin having a base for mounting at an underside of the surfcraft, the base having an integral projection extending therefrom; and a receipt means for mounting in the underside of the surfcraft and adapted for receiving the projection for rotation and selective fastening therein.

The receipt means thus enables an in use rotation and fastening of the fin with respect to the surfcraft. Such a configuration results in a fin that can be oriented in a number of different rotational positions on the underside of the surfcraft and that can be selectively fastened in each position to rapidly change the performance of the surfcraft.

Preferably the projection extends downwardly from the fin base and is received within a corresponding aperture formed in the receipt means, the selective fastening being achieved through the use of a releasable fastening means mounted in the receipt means and adapted for releasably engaging the projection when it is located in the aperture. Preferably the projection is a disc-shaped element that extends laterally and equidistanuy outwardly from opposing sides of the fin at the base thereof, the receipt means is a socket formation, and the aperture is a corresponding circular recess formed in the socket formation into which the element can be arranged in a close-fit arrangement, whilst still being rotatable merewithin, wherein one side of the element is coplanar with the base of the fin, and the opposing side faces the base of the recess when the element is located therein.

Preferably a tube is arranged to extend from the socket formation and through to the opposing upperside of the surfcraft when the socket formation is mounted in the underside of the surfcraft, the tube being adapted in use to support the fastening means therein, such that in use, one end of the tube opens onto the upperside of the board, and the other end is received in an annular shaped projecting skirt located on the underside of the socket formation and opens onto a passage formed in the socket formation which intum opens onto the recess. Preferably the other end of the tube has a peripheral and circumferential flange formed therearound and an external tapered face formed on the flange, with a correspondingly tapered face being formed within the projecting skirt, such that the flange can be snap or interference-fitted in the skirt.

Preferably the fastening means is a threaded bolt or screw partially located within the socket, with a threaded shank of the bolt or screw extending through the passage to releasably and threadingly engage a corresponding threaded recess formed in the underside of the element when located in the recess, with the threaded bolt or screw having a head that is retained in a cavity defined between and by the flanged end of the tube and the underside of the socket formation; wherein in use, the head is engageable by an appropriate tool that is inserted into the tube from the surfcraft upperside and through an opening at the flanged end of the tube. With this adaptation of the tube and socket formation, and when the element is located in the recess, rotation of the threaded bolt or screw in a first direction causes the threaded shank to fasteningry engage the threaded recess in the element until it is fastened in the socket recess against rotation. Rotation in an opposite direction results in the head being displaced against the flanged end of the tube, and further rotation causes the element to be forced from its fastening in the recess, once again enabling rotation of the fin with respect to the surfcraft.

Preferably side walls of the recess interior and the disc-shaped element have correspondingly tapered surfaces that interengage in use to enhance fastening, wherein the tapered surface on the disc shaped element tapers inwardly from said one side to the opposite side, and the tapered surface in the recess tapers correspondingly outwardly from the base of the recess to a surface located at the underside of the surfcraft when the socket formation is mounted therein.

In a second aspect, the present invention provides a device for releasably attaching ₅ a base of a structure to a support mountable within a given side of a surfcraft, the base being capable of rotation within the support, and the device including: an engagement means arranged in the base; and a fastening means adapted for releasably engaging the engagement means and retained in the support to be movable between first and second positions such that: , _Q in the first position the fastening means engages the engagement means to fasten the base relative to the support, and in the second position the fastening means is released for movement with reference to the support to enable the base to be rotated within the support; wherein the support is adapted for interacting with the fastening means when the fastening means is moved to the second position such that the base is released for rotation relative to ₅ the support.

With such a device structures such as fins, blocks, leg rope and hand strap plugs, attachment devices, deck pads, body strap fastening points etc., can be readily mounted for rotation and fastening to a surfcraft.

It is most preferred that the support is the receipt means as defined with reference _Q to the first aspect of the invention, that the structure incorporates the integral projection of the first aspect of the invention, and that the fastening and engagement means are as defined with respect to the first aspect of the invention. Thus, the second aspect can incorporate all of the advantages of the first aspect of the invention.

5 BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of the present invention, preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which : 0

Figure 1 shows a sectional side elevation of a preferred fin unit according to the invention when mounted to a surfcraft;

Figure 2 shows a plan elevation of the fin unit of Figure 1; and

Figure 3 shows a perspective exploded view of the fin unit of Figures 1 and 2. 5 MODES FOR CARRYING OUT THE INVENTION

Referring to the drawings, a fin unit 10 for mounting to a surfcraft 11 includes a fin 5 12 having a base 14 adapted for location adjacent to an underside 15 of the surfcraft; (only a section of the surfcraft is shown in Figure 1). A projection in the form of a circular lug 16 extends from the base and is shaped to fit snugly in a circular socket 18 fastened in the underside of the surfcraft. The lug includes a releasable fastening system in the form of a threaded passage 20 formed therein, which can threadabry receive a screw (or bolt) 22 _ o extending through socket 18.

The screw is held captive in the surfcraft by the co-operation of the socket with a tubular member 24 extending from the socket (i.e. when the tubular member and socket are mounted together they define a chamber 25 in which the screw head 26 is retained for rotation therein). The tubular member has a flanged end 27, arranged at that end joined to ₅ the socket, that is received in an annular skirt 28 formed on the underside of the socket. The flanged end and skirt each have reverse tapered surfaces formed thereon which interengage at region 29 and enable the flanged end to be snap-locked (or interference fitted) into the skirt prior to (or after) the tubular member is fitted to the surfcraft. This arrangement thus assists a manufacturer when fastening the socket and tubular member in 0 a surfcraft, because the socket and tubular member can be assembled as a unit prior to fixing the unit in the surfcraft and ensures that the chamber and the hole in the socket through which the screw passes are appropriately aligned.

The screw head can be accessed by an appropriate tool (e.g. a screw driver) via a bore 30 formed in the tubular member, and bore 30 opens onto surfcraft upperside 32 at opening 34. In use, the opening 34 is closed with a small plug (not shown) to prevent the ingress of water, sand etc.

As can be seen in Figures 1 and 3, the lug 16 tapers inwardly from planar upper surface 36, coplanar with the fin base 14, to planar lower surface 38. This defines a tapered side 40 of the lug that is shaped to engage a correspondingly tapered inner surface 42 formed in socket 18. The circular shaping of lug 16 and socket 18 (Figures 2 and 3) facilitates rotation of the fin 12 on the underside of the surfcraft (i.e. the lug 16 rotates both clockwise and anti-clockwise in the socket 18 as shown in Figure 2 by arrows C, AC). (The lug and socket can also be spherical, hemispherical and semi-spherical (e.g. such as a ball and socket arrangement, but not shown in the drawings)). The rotational position of the fin can be easily and rapidly changed when the fastening system is released. However, when screw 22 is rotated so that the lug 16 is drawn into the socket 18, the interengagement of tapered surfaces 40 and 42 locks the lug and socket together and prevents rotation of the fin with respect to the surfcraft, thereby fastening the position of the fin for subsequent use.

It will be seen in Figure 1 that the chamber 25 provides sufficient space for the 5 screw head 26 to rotate therein, but the walls thereof are in a close facing relationship to the outer surface of the screw head. This positioning has two distinct effects: -Firstly, it always directs the screw shank to point generally upwardly, so that it can be readily located in the threaded passage 20 when the lug 16 is positioned in socket 18. -Secondly, when the lug has been fastened in the socket by rotation of the screw in a given ₀ direction, and when it is desired to release the lug, (e.g. for rotation or removal of the fin), rotation of the screw in the opposite direction causes the screw head initially to move downwardly in the chamber (i.e. in the direction of arrow D in Figure 1). This occurs because the lug and socket have previously been fastened together and thus the lug is initially prevented from rotation in the socket. However, further rotation of the screw ₅ causes the screw head 26 to engage the flanged end 27 of the tubular member, thereby preventing its further downward travel in direction D. Further screw rotation then causes the lug to be forced upwardly (i.e. because the screw head is restrained from travelling downwardly any further) and hence the lug forced upwardly and is released from the socket, thereby once again allowing rotation or removal of the fin. o This effect can be achieved without any considerable effort by a user, and yet does not compromise the positional fastening force of the fastening system. This arrangement of the fastening means thus provides a very rapid and effective way for tightly fastening and easily releasing the fin for positioning, rotation and removal.

When fitting the fin unit to a surfcraft, a hole corresponding in diameter to the ₅ tubular member external diameter is cut from the surfcraft underside through to the underneath of the surfcraft upperside (i.e. deck). A second larger diameter hole corresponding to the socket depth and external diameter is then cut in the surfcraft adjacent to the underside thereof and concentric with the first hole. The tubular member and socket are then affixed in their respective holes (e.g. by gluing in with a polymer resin). _Q The fastening system described above can be embodied in other forms. Instead of employing a taper arrangement between the lug and socket, other types of frictional engagement systems can be employed. For example, serrations can be formed on either or both of the lug outer side and the socket inside surfaces, and/or on either or both of the lug base and opposing socket floor to facilitate fastening together of the lug and socket against rotation when the two are brought into close engagement. The affixing can be achieved by devices other than a screw, for example, any other type of releasable locking device (e.g. such as push pins, latches etc.). The screw (or other locking device) can also be positioned elsewhere in the socket. For example, it can extend from the outer surface of the socket, through a side wall thereof and into releasable engagement with the lug.

The fin unit can be formed by casting, injection moulding or other suitable techniques, from plastics including polyurethanes and polymer resins, such as epoxy resins, polyesters, etc. Marry different types of fin shapes and sizes can be employed with the fin unit without detracting from its performance. The fin unit can be very easily installed in a surfcraft by a manufacturer because of its compact size and because it can be supplied or arranged as a single unit and not as a large number of separate parts. The socket arrangement allows a surfcraft to be finished (e.g. by sanding) after the socket has been fitted to the surfcraft, and then the fin(s) can be subsequently and easily fitted as described above. Also, one or more fin units can be fitted to a surfcraft as appropriate.

It is known that the position and size of the fin on the underside of a surfcraft is influential on the performance of the craft in the water. The embodiments described herein enable a rapid and easy interchange of fins on a surfcraft, so that their number, size and angle can be changed to alter the performance characteristics of the surfcraft. With the present invention, a user is able to obtain a wide variety of different effects out of a single surfcraft, not previously achievable in such an effectively variable and rapid manner.

Whilst the invention has been described with reference to a number of preferred embodiments, it should be appreciated that the invention can be embodied in many other forms.

Claims

1. A fin unit for a surfcraft including: a fin having a base for mounting at an underside of the surfcraft, the base having an 5 integral projection extending therefrom; and a receipt means for mounting in the underside of the surfcraft and adapted for receiving the projection for rotation and selective fastening therein.

2. A device as claimed in claim 1, wherein the projection extends downwardly from the fin 0 base and is received within a corresponding aperture formed in the receipt means, the selective fastening being achieved through the use of a releasable fastening means mounted in the receipt means and adapted for releasably engaging the projection when it is located in the aperture.

5 3. A device as claimed in claim 2, wherein the projection is a disc-shaped element that extends laterally and equidistantly outwardly from opposing sides of the fin at the base thereof, the receipt means is a socket formation, and the aperture is a corresponding circular recess formed in the socket formation into which the element can be arranged in a close-fit arrangement, whilst still being rotatable therewithin, and wherein one side of the o element is coplanar with the base of the fin, and the opposing side faces the base of the recess when the element is located therein.

4. A device as claimed in claim 3, wherein a tube is arranged to extend from the socket formation and through to the opposing upperside of the surfcraft when the socket formation is mounted in the underside of the surfcraft, the tube being adapted in use to support the fastening means therein such that in use, one end of the tube opens onto the upperside of the board, and the other end is received in an annular shaped projecting skirt located on the underside of the socket formation and opens onto a passage formed in the socket formation which intum opens onto the recess.

A device as claimed in claim 4, wherein the other end of the tube has a peripheral and circumferential flange formed therearound and an external tapered face formed on the flange, with a correspondingly tapered face being formed within the projecting skirt, such that the flange can be snap or interference - fitted in the skirt.

6. A device as claimed in claim 4 or claim 5, wherein the fastening means is a threaded bolt or screw partially located within the socket, with a threaded shank of the bolt or screw extending through the passage to releasably and threadingly engage a corresponding threaded recess formed in the underside of the element when located in the recess, with the threaded bolt or screw having a head that is retained in a cavity defined between and by the flanged end of the tube and the underside of the socket formation; wherein in use, the head is engageable by an appropriate tool that is inserted into the tube from the surfcraft upperside and through an opening at the flanged end of the tube.

7. A device as claimed in any one of claims 3 to 6, wherein side walls of the recess interior and the disc-shaped element have correspondingly tapered surfaces that interengage in use to enhance f-istening, wherein the tapered surface on the disc shaped element tapers inwardly from said one side to the opposite side, and the tapered surface in the recess tapers correspondingly outwardly from the base of the recess to a surface located at the underside of the surfcraft when the receipt means is mounted therein.

8. A device for releasably attaching a base of a structure to a support mountable within a given side of a surfcraft, the base being capable of rotation within the support, and the device including: an engagement means arranged in the base; and a f-ιstening means adapted for releasably engaging the engagement means and retained in the support to be movable between first and second positions such that: in the first position the fastening means engages the engagement means to fasten the base relative to the support, and in the second position the fastening means is released for movement with reference to the support to enable the base to be rotated within the support; wherein the support is adapted for interacting with the fastening means when the fastening means is moved to the second position such that the base is released for rotation relative to the support.

9. A device as claimed in claim 8 wherein the support is the receipt means as defined in any one of claims 1 to 7; the structure is the fin with integral projection as defined in any one of claims 1 to 7; and the fastening means is as defined in any one of claims 2 to 7.