Abstract:
A fin box for releasable attachment of a fin to the body of a surfboard or the like; said fin including a fin-tab associated therewith; said fin box adapted for insertion into and retention within said surfboard; said fin box further adapted for reception and releasable retention of a plurality of fin-tab configurations thereby to releasably retain said fin in fixed relationship to said surfboard; and wherein a first surface of said fin box is of a length and a width sufficient to support said fin entirely so that no portion of said fin is in contact with the body of said surfboard or the like.

Description:
RELATED APPLICATION  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/654,338, filed Feb. 18, 2005, and also claims priority to Australian Provisional Application No. 2004907054, filed Dec. 13, 2004, Australian Provisional Application No. 200407120, filed Dec. 14, 2004, and Australian Innovation Application No. 2005100116, filed Feb. 8, 2005 which are hereby incorporated in their entirety by reference herein 
     
    
     BACKGROUND  
       [0002]     The present invention relates to fins and their attachment to small water craft and, more particularly to a system for attaching a variety of fin configurations to a surfboard.  
         [0003]     As with many types of sporting equipment, many variations on the basic article have been developed to tailor the article to the preferences of the user and the conditions of use. So it is with the fins attached to the rear undersides of surfboards.  
         [0004]     It is an obvious advantage for the owner of a board to be able to interchange the fin or fins both to experiment, with the aim of finding the fin most suited to their body weight and style of riding, and from time to time to suit the conditions in which the board is to be ridden.  
         [0005]     Interchangeable fin systems are known and comprise of a selection of fins retained in a so-called fin box. Particular examples may be found in U.S. Pat. No. 5,830,025, U.S. Pat. No. 5,975,974 and WO 01/70565. The fin box is generally a permanent fixture built into the body of the board during its manufacture and, again generally includes a slot or slots into which the tab or heel of the fin may be inserted. The means for retaining an inserted fin securely in the fin box are many and varied, ranging from relatively simple snap-in systems to arrangements incorporating fasteners requiring the application of tools to install and remove a fin from its fin box.  
         [0006]     A disadvantage with these systems is that the fin box is designed to take only one configuration of a fin tab, so that the owner of a board who wishes to change or experiment with a variety of fins from manufacturers other than the manufacturer of his or her board, or at least the fin boxes fitted to the board, is restricted in choice.  
         [0007]     It is an object of the present invention to address or at least ameliorate some of the above disadvantages.  
       BRIEF DESCRIPTION OF INVENTION  
       [0008]     In one aspect, the invention is structure for releasable attachment of a fin to the body of a surfboard or the like; said fin including a fin-tab associated therewith; said structure adapted for insertion into and retention within said surfboard; said structure further adapted for reception and releasable retention of a plurality of fin-tab configurations thereby to releasably retain said fin in fixed relationship to said surfboard.  
         [0009]     In another aspect, the invention is a method for releasable attachment of a plurality of fin-tab configurations of at least one fin of a surfboard; said method including the steps of: 
        (a) providing at least a centre fin box embedded in said surfboard; said fin box comprising an elongate body with a recess,     (b) withdrawing set-screws provided in angled threaded holes in said fin box sufficient to allow insertion of said fin-tab into said recess,     (c) driving said set-screws into contact with said fin-tab.        
 
         [0013]     In another aspect, the invention is a fin box for releasable attachment of a fin to the body of a surfboard or the like; said fin including a fin-tab associated therewith; said fin box adapted for insertion into and retention within said surfboard; said fin box further adapted for reception and releasable retention of a plurality of fin-tab configurations thereby to releasably retain said fin in fixed relationship to said surfboard; and wherein a first surface of said fin box is of a length and a width sufficient to support said fin entirely so that no portion of said fin is in contact with the body of said surfboard or the like.  
         [0014]     In another aspect, the invention is a fin retention system adapted to be positioned within a water craft, the system comprising:  
         [0015]     a body that defines an opening wherein the opening is sized so as to receive a plurality of different types of fins, each of the plurality of different type of fins having fin tabs having different configurations wherein the body is adapted to be mounted through an outer surface of the water craft;  
         [0016]     a flange that surrounds the opening in the body so as to extend outward therefrom wherein the flange is positioned generally flush with the outer surface of the water craft when the body is positioned within the water craft;  
         [0017]     a first retention mechanism positioned within the body that engages with a first configuration of fin tabs; and 
        a second retention mechanism positioned within the body that engages with a second configuration of fin tabs.        
 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0019]     Embodiments of the present invention will now be described with reference to the accompanying drawings wherein:  
         [0020]      FIG. 1  is a view of the underside of a surfboard fitted with the fin attachment system for a typical three-fin arrangement according to a preferred embodiment of the invention;  
         [0021]      FIG. 2  is an end view of the surfboard of  FIG. 1  showing a centre and left and right fins;  
         [0022]      FIG. 3  shows side views and plan views of four fin and fin-tab configurations able to be fitted to a preferred embodiment of the fin attachment system, or fin box of the present invention;  
         [0023]      FIG. 4  is a perspective view from below of a centre fin-box;  
         [0024]      FIG. 5  is a cross section view of the fin box of  FIG. 4  with a fin retained in the fin box;  
         [0025]      FIG. 6  is a side cross section view of the fin box of  FIGS. 4 and 5 ;  
         [0026]      FIG. 7  is a plan view of the fin box of  FIG. 6 ;  
         [0027]      FIG. 8  is a side and perspective view of an insert for use with the fin box of  FIGS. 6 and 7 .  
         [0028]      FIG. 9  is a sectioned end view of the fin box of  FIGS. 6 and 7  when fitted with fin  3 A of  FIG. 3 ;  
         [0029]      FIG. 10  is a sectioned side view of the fin box of  FIGS. 6 and 7  when fitted with fin  3 C of  FIG. 3 ;  
         [0030]      FIG. 11A  is a plan view of a left side fin box;  
         [0031]      FIG. 11B  is a series of cross sections taken along the length of the fin box of  FIG. 11A ;  
         [0032]      FIG. 11C  is an end view of a side fin with an in-line fin-tab;  
         [0033]      FIG. 11D  is an end view of a side fin with a canted fin-tab.  
         [0034]      FIG. 12  is a perspective view of a preferred form fin box according to the invention with an adjustable fin;  
         [0035]      FIG. 13  is a perspective view of an insert for use in the fin box of  FIG. 11A ;  
         [0036]      FIG. 14  is sectioned view of a fin inserted in the fin box of  FIG. 11A  with the insert of  FIG. 13 .  
         [0037]      FIG. 15  is a perspective view of the fin box of  FIG. 4  showing a further retaining system for fin  3 D of  FIG. 3 .  
         [0038]      FIG. 16  is a sectioned end view of fin  3 D retained in the fin box of  FIG. 4 .  
         [0039]      FIG. 17  shows plan and end views of a further preferred embodiment of a left, right and centre fin box,  
         [0040]      FIGS. 17A, 17B  and  17 C are sectioned end views of the left, right and centre fin boxes of  FIG. 17 ,  
         [0041]      FIG. 18  is a sectioned side elevation view of one of the fin boxes of  FIGS. 17 , and  17 A to  17 C with a dual fin-tab fin installed,  
         [0042]      FIGS. 18A, 18B  and  18 C are detailed perspective views of inserts for the centre, left and right hand fin boxes of  FIGS. 17 and 17 A to  17 C,  
         [0043]      FIG. 19  is a sectioned side elevation view of one of the fin boxes of  FIGS. 17 and 17 A to  17 C without an insert and with a fin with the fin-tab of  FIG. 3C  installed,  
         [0044]      FIGS. 19A and 19B  are sectioned views of a fin box with a recess greater in length than the fin-tab of a fin allowing fore and aft adjustment of the location of the fin-tab in the fin box,  
         [0045]      FIG. 20  shows plan and sectioned end elevation views of a further preferred embodiment of a centre, left and right fin box according to the invention,  
         [0046]      FIG. 21  is a sectioned side elevation view of still a further preferred embodiment of a fin box with a dual fin-tab fin installed.  
         [0047]      FIGS. 21A and 21B  are sectioned side elevation views of a fin with dual fin-tabs installed in a recess of a fin box wherein the recess is of a length allowing fore and aft adjustment of the fin in the fin box,  
         [0048]      FIG. 22  shows plan and sectioned end elevation views of a further preferred embodiment of a fin box,  
         [0049]      FIGS. 23A and 23B  are side views of a further preferred embodiment of the fin box.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
     First Preferred Embodiment  
       [0050]     In a first preferred embodiment of the invention and with reference to  FIGS. 1 and 2 , a surfboard  10  is fitted with three fin retaining structures  12 ,  13  and  14 , commonly known as fin boxes, embedded into the underside  16  of surfboard  10 . Fin box  12  provides for a centre fin  17 , while fin boxes  13  and  14  accommodate left outside fin  18  and right outside fin  19  respectively.  
         [0051]     Fins  17 ,  18  and  19  are held in retaining structures of fin boxes  12 ,  13  and  14  by a fin-tab formed at the top edge of the fin, that is that edge of the fin substantially flush with the surface of the underside of the surfboard. Examples of typical fins and fin-tabs commercially available are shown in  FIG. 3 .  
         [0052]     Referring again to  FIG. 2 , it will be noted that while centre fin  17  has its central plane normal to the underside  16  of surfboard  10 , the left and right outside fins are canted outwardly relative to that plane. That canting is generally at an angle of 5 degrees. Canting of outside fins may be introduced either by introducing the cant angle within the recess of the left and right fin boxes, or by the canting of the plane of the fin relative to the fin-tab. The fin boxes  13  and  14  of the present invention provide for canting of outside fins which have the fin-tab in-line (that is, no canting of the fin-tab), as well as allowing the use of outside fins canted relative to the fin-tab, as will be explained in more detail below.  
         [0053]     Turning now to the specific structures of a preferred embodiment of fin boxes according to the invention for centre and outside fins able to accept a multiplicity of commercially available fins, both with in-line and canted fin-tabs. With reference to  FIG. 4 a  centre fin box  20  is constructed as a generally elongate body  22  provided with a recess  24 . Body  22  has a first surface  25  which, when fin box  20  is installed in the body of a surfboard (as shown in  FIGS. 1 and 5 ) is generally flush with the surface of the underside  16  of the board  10 . First surface  25  includes a peripheral flange  26  extending outwardly from the body  22 .  
         [0054]     Recess  24  extends into the body to a depth sufficient to accept any of the fin-tabs of the commercially available fins shown in  FIG. 3 . As best seen in  FIGS. 4 and 5 , body  22  is further provided with a pair of buttress elements  28  at each side of body  22 , extending from the upper surface of flange  26  and tapering to the edge of surface  31 . Angled threaded holes  34 A and  34 B are provided along each side of recess  24 , passing from surface  25  to emerge at inside surfaces of the recess as best seen in  FIGS. 5, 6  and  7 . A further angled threaded hole  35  emerges at the forward inside end wall  36  of recess  24 . A vertical threaded hole  37  is also provided as shown in  FIGS. 4 , and  7 .  
         [0055]     The width and configuration of the recess is such as to allow insertion of the fin-tabs shown in  FIG. 3 . Thus for example, the lateral recesses  23  extending outwardly from the main recess  24  are adapted to accept the projecting elements  30  of fin-tab  29  of fin  3 A in  FIG. 3 . As can be seen in  FIG. 9  the fin-tab of fin  3 A may be securely retained in recess  24  of fin box  20  by a set-screw  38  driven into the angled threaded hole  34 A on one side of recess  24  and engaging with cylindrical portion  40  of the fin-tab.  
         [0056]     With reference to  FIGS. 6 and 7 , recess  24  is provided with a retention member  32  extending across the width of recess  32  and projecting from the rearward end wall  33  of recess  24 . Retention member is adapted for engagement with a rear notch  35  in the fin-tab  34  of fin  3 C (shown in  FIG. 3 ). As shown in  FIG. 10 , fin-tab  34  of fin  3 C is retained in fin box  20  at the rear by the engagement of notch  35  with retention member  32 , and at the front by set-screw  38  engaging front notch  34 . Additionally, set-screws  38  (not shown in  FIG. 10 ), may be driven through angled threaded holes  34 A and  34 B against the sides of fin-tab  34 .  
         [0057]     The fin  3 B shown in  FIG. 3  has a fin-tab made up of two sections  42 A and  42 B. To accommodate this fin-tab in the fin box of the present embodiment of the invention, there is provided an insert  44 A shown in  FIG. 8 . Insert  44 A is of similar external dimensions as the fin-tab  34  of fin  3 C, and is provided with similar rear notch  45  and front notch  46  to enable the insert  44 A to be retained in fin box  20  by retention member  32  and the set screw through front threaded hole  35 . Insert  44 A is further provided with cut-out portions  48 A and  48 B, sized to receive fin-tab sections  42 A and  42 B. These sections are then secured in fin box  20  by set-screws driven through angled threaded holes  34 A and  34 B with the set-screws driving up against the sides of fin-tab sections  42 A and  42 B.  
         [0058]     With reference to  FIGS. 15 and 16 , fin  3 D (shown in  FIG. 3 ), has a fin-tab  50  with slot  51  at the interface between the fin and the tab. This fin, once inserted into the recess  24  of the fin box, is retained by a plate  53  inserted into slot  51  and secured to the fin box by screw  52  screwed into vertically threaded hole  237 .  
         [0059]     The side fin boxes  13  and  14  are of similar configuration to that of the centre fin box thus far described, but have recesses that are somewhat modified. The left and right fin-boxes are of symmetrical configuration and only the left fin box will be described in detail.  
         [0060]      FIG. 11A  shows a plan view of the flanged face of a fin box  13  for the left fin of a three-fin surfboard. The recess  124  of this box has sections  128  of the inside wall of the recess closest to the outside edge of the surfboard (to the left in  FIG. 11A ) sloping outwardly by 5 degrees as indicated by the sectional views A-A to D-D in  FIG. 11B . The opposing end walls  123 A and  123 B of lateral recesses  123  which extend outwardly from main recess  124 , slope inwardly so as to be parallel to the modified sloping wall sections of the recess  124  towards the outside edge of the surfboard, as can be seen in section C-C.  
         [0061]     The outward sloping sections  128  at A-A to D-D are so placed within recess  124  as to accommodate side fin configurations with in-line fin-tabs such as shown in  FIG. 11C  and canted fin-tabs as shown in  FIG. 1D . Of the fin-tab configurations shown in  FIG. 3 , which may be accommodated in the fin box of the present invention, fins  3 A and  3 B have in-line fin-tabs for both left and right fins, while fin  3 C and fin  3 D have fin-tabs canted by 5 degrees for the left and right outside fins.  
         [0062]     It will be seen from the placement of the outwardly sloping sections  128  of recess  124  in  FIGS. 11A and 11B , that in-line fin-tab  29  of fin  3 A when inserted into recess  124 , will be canted outwardly by 5 degrees, since all the vertical faces of that fin tab will slide into those sections at A-A, B-B and C-C which have the side surfaces sloping at 5 degrees.  
         [0063]     Likewise, the fin-tab configuration of fin  3 B will be accommodated at sections B-B and D-D, when combined with the insert  44 B of  FIG. 13  as previously described, but which, for this insert has a 5 degree cant built into cut-out portions  48 C and  48 D.  FIG. 14  shows fin  3 B located in recess  24  with insert  44 B, and locked in place by a set-screw through angled threaded hole  135 .  
         [0064]     Fin-tab  34  of fin  3 C, and fin-tab  50  of fin  3 D however need to be retained in the fin box without the 5 degree cant. This is achieved by the remaining sections  126  of recess  124 , which retain parallel vertical walls.  
         [0065]     As well, fin box  13  is provided with one pair of angled threaded holes  134 A and  134 B only along that side of the recess  124  away from the outside edge of the surfboard (that is to the right in  FIG. 11A ). Thus the in-line fin-tabs  29  of fin  3 A is driven by the set screw through hole  134 A into the desired canted position within recess  124 , against the sloping side surfaces towards the outside of the surfboard.  
         [0066]     With reference again to  FIGS. 13 and 14 , the in-line fin-tabs  42 A and  42 B of fin  3 B are positioned at the 5 degree cant by inserting the fin-tabs into the recess portions  48 C and  48 D of insert  44 B. The fin-tabs are then secured by set-screws  38  that pass through slots  50  in recesses  44 C and  44 D to drive the fin-tabs against the outwardly sloping side surfaces of recess  24  and so canting the fin towards the outside edge of the surfboard by 5 degrees.  
         [0067]     Fin-tab  34  of fin  3 C, and fin-tab  50  of fin  3 D, are retained in the normal vertical orientation as previously described for the centre fin box.  
         [0068]     The centre, left and right fin boxes of the present invention as described above are further able to accept and retain an adjustable fin. As shown in  FIG. 12 , an adjustable fin  210  is provided with a shortened fin-tab  212 . Preferably, fin tab  212  is 20 mm shorter than recess  224 , so that fin  210  may be moved forward or rearward by 10 mm from a median position. Fin-tab  210  is still provided with notch  235  so as to allow the fin-tab to be located up against the rear wall  233  and not interfere with the retention member ( 32  in  FIGS. 6 and 7 ) when located in its rearmost position. However, fin-tab  212  does not rely for retention in recess  224  on the retention member, nor on the forward set-screw in angled threaded hole  235 .  
         [0069]     In this embodiment, the fin-tab  212  of fin  210  is provided with recesses  214 A and  214 B. For a left side fin (as shown in  FIG. 12 ) or right side fin box, both recesses are on one side of the fin-tab, that is, on that side on which the angled threaded holes  234  are positioned. For a centre fin, the recesses are provided one on each side of the tab to correspond with the equivalent angled threaded holes of a centre fin box as described herein above. The length of recesses  214  is such as to permit the set-screws driven through angled threaded holes  234  to engage with the recesses regardless of the user&#39;s preferred position of the fin.  
       Second Preferred Embodiment  
       [0070]     In a further preferred embodiment of the invention, the fin boxes are somewhat simplified from those described above and shown in FIGS.  6  to  8  and  FIGS. 11 and 12 . In this embodiment the left, right and centre fin boxes cater for fins with the fin tab configurations of  FIGS. 3B and 3C .  
         [0071]     With reference to  FIG. 17 , a centre fin box  300 , right hand fin box  302  and left hand fin box  304  are each formed as before, as an elongate body  306  provided with a central recess  308  and a peripheral flange  310 . As can be seen in the sectioned views of each of  FIGS. 17A  to  17 C, recesses  308  extend from a first outer surface  316  to proximate an opposite inner surface  314 . Shown as dashed lines in  FIG. 17 , and as best seen in  FIG. 18 , the recess  308  of this embodiment is also provided with a retaining structure  319  projecting from the rearward end wall  311 .  
         [0072]     First outer surface  316  comprises a first inner portion of peripheral flange  310  around recess  308 . An outer portion  318  of flange  310 , is offset from first outer surface  316 . As can be seen in  FIGS. 17, 17A ,  17 B and  17 C, the offset between first outer surface  316  and the outer portion  318  of flange  310  is such that when the fin boxes are installed in the body of a surfboard, the surface of outer portion  318  is flush with the surface  315  of the foam core  307  of a surfboard and the first outer surface  316  is then flush with surface  322  of the finished outer fibreglass skin  320  of the underside surface  322 .  
         [0073]     The length and breadth of first outer surface  316  which, though flush with the surface  322  of the surfboard, remains exposed, is such that no part of a fin installed in a fin box  300 ,  302  or  304  is in contact with the underside surface  322 . The fin blade is thus fully supported by and within the extent of first outer surface  316 .  
         [0074]     With reference to  FIGS. 17, 17B  and  17 C, the right hand fin box  302  and left hand fin box  304  of this embodiment are each provided with two outwardly sloping wall sections  309 . Outwardly sloping wall sections  309  of fin boxes  302  and  304  slope towards the right hand side and left hand side respectively of a surfboard. The length and disposition of sloping wall sections  309  conforms to the length and spacing of the dual fin-tabs  42 A and  42 B of the fin-tab configuration “B” of  FIG. 3 . Provided opposite each sloping wall section  309  is an angled threaded hole  313  passing from first outer surface  316  to the adjacent sidewall of recess  308 .  
         [0075]     The right hand and left hand fin boxes  302  and  304  respectively of the present embodiment are provided with a right hand removable insert  330  and a left hand removable insert  332  respectively as shown in  FIGS. 17, 17B  and  17 C. Removable inserts  330  and  332  are of a length, width and depth such as to substantially fill recesses  308 . With reference to  FIGS. 18B and 18C , removable insert  330  and  332  are each provided with a notch  334  at the rearward end of the insert, adapted to releasably engage with the retaining structures  319  of recesses  308 .  
         [0076]     Removable inserts  330  and  332  are each further provided with a pair of receiving recesses  331  and  333  respectively. The length and disposition of recesses  331  and  333  are such that when the inserts are inserted into the respective recesses  308  of right hand fin box  300  and left hand fin box  302 , the receiving recesses coincide with sloping wall sections  309 . Inner walls  336  of receiving recesses  331  and  333  are provided with slots  338  to allow set screws  339  driven through angled threaded holes  313  to pass through the slots  338  and engage with the dual fin-tabs of a dual fin-tab fin.  
         [0077]     The inner walls  336  of receiving recesses  331  and  333  slope inwardly with the same degree of slope as that of sloping wall sections  309  of recesses  308 , so that with the inserts located in recesses  308  the sloping wall sections  309  are parallel to the inner walls  336  of receiving recesses  331  and  333 . The separation between these opposing parallel walls conforms to the thickness of the dual fin-tabs  42 A and  42 B of  FIG. 3 .  
         [0078]     As can be seen in the sectioned views of  FIGS. 17B and 17C , since these dual fin-tabs are in-line with the median plane  340  of the fins  342 , the fins  342  assume an outwardly canted angle relative to the underside surface  322 . Thus a dual fin-tab fin inserted into right hand fin box  302  fitted with removable insert  330 , is canted towards the right hand side of a surfboard, while an identical fin likewise inserted into the left hand fin box  302  and its associated removable insert  332 , is canted towards the left hand side of the surfboard.  
         [0079]     With reference now to  FIGS. 17 and 17 A, the recess  308  of centre fin box  300  is not provided with sections of sloping walls; opposing sidewalls being parallel and vertical relative to the underside  322  of a surfboard. The centre fin box  300  is also provided with two angled threaded holes  317  spaced apart and located along the length of the recess as are the threaded angled holes  313  of the right hand and left hand fin boxes, but disposed one on either side of recess  308 .  
         [0080]     Centre fin box  300  is also provided with a removable insert  350  (shown in  FIG. 18A ) of similar outward configuration and dimensions as the removable inserts  330  and  332  for the right hand and left hand fin boxes described above. Removable insert  350  is also provided with receiving recesses  352  sized and positioned along the length of the insert as are the receiving recesses  331  and  333  of the right hand and left hand inserts. However, the rear walls  354  of these recesses are not sloping, so that when the insert  350  is inserted into recess  308  of the centre fin box, the recesses form parallel sided and vertically disposed recesses.  
         [0081]     Thus a dual fin-tab fin installed in the centre fin box  300  with its removable insert  350 , will be vertical relative the underside  322  of a surfboard. Because of the arrangement of the angled threaded holes of the centre fin box, only the rear wall  354  of the rearward receiving recess need be provided with a slot  356  for a securing set screw to pass through.  
         [0082]     With the respective inserts  330 ,  350  and  332  of the right hand, centre and left hand fin boxes removed, the fin boxes can receive a fin-tab configuration of the type shown as “C” in  FIG. 3 , as can be seen in  FIG. 19 . For the right hand and left hand fin to be canted outwardly to the right and left hand sides of a surfboard respectively, fin-tabs canted relative to the plane of the fin as shown in  FIG. 11D  can be used.  
         [0083]     The right hand, centre and left hand fin boxes of the present embodiment are further able to accommodate and allow fore and aft adjustment of fins with the fin-tab configuration shown in  FIG. 12 . These fins are provided with fin-tabs specific to right hand, centre and left hand fins, with the fin tabs of the right and left hand fins canted relative the blade of the fin so as to set the fin at an outwardly sloping angle relative the underside of the surfboard when the fin-tab is retained between the parallel and vertical opposite walls of the fin box recesses.  
         [0084]     The fore and aft adjustment of this fin-tab configuration is provided by the length of the fin-tab being some 20 mm shorter than the length of the fin box recess.  FIGS. 19A and 19B  show a fin  440  with a shorter fin-tab  442  in a maximum forward position and a maximum rearward position respectively. The fin-tab  442  is secured in the fin box by the set screws previously described. As well it will be noted that, regardless of the fin&#39;s adjusted fore-aft position, the blade is fully supported on the surface of inner portion  316  and is not in contact with the surface  444  of the surfboard.  
       Third Preferred Embodiment  
       [0085]     Turning now to  FIGS. 20 and 21 , in this further preferred embodiment of the invention, as for the second preferred embodiment described above, a right hand fin box  400 , centre fin box  402  and a left hand fin box  404  are provided, all with the same general external configuration of the fin boxes of the second preferred embodiment shown in  FIG. 17 .  
         [0086]     However, in this embodiment, the central recess  408  of each fin box is shortened to a length equal to that from leading edge  420  of the forward fin-tab  421  of a dual fin-tab fin  426 , to the trailing edge  422  of the rearward fin-tab  423 , as shown in  FIG. 21 . Also, there is no retaining structure projecting from the rearward end wall of the recess.  
         [0087]     For the right hand fin box  400  and the left hand fin box  404 , the central recesses  408  have parallel sidewalls canted at an angle to the underside surface  418  of a surfboard, while the sidewalls of the recess of the centre fin box are parallel and vertical.  
         [0088]     With reference to  FIGS. 21A and 21B , fore and aft adjustment of a dual fin-tab fin  526  in the fin boxes may be provided by a recess length longer than the distance between the leading edge  520  of the forward fin-tab  521  and the trailing edge  522  of the rearward fin-tab  523 . Thus as shown in  FIGS. 21A and 21B , a recess  530 , 10 mm longer than the overall length of the dual fin-tabs  521  and  523  will allow the fin  526  to be adjusted plus or minus 5 mm from a median position between the fully forward location of  FIG. 21A  and the fully rearward position of  FIG. 21B . The overall length and breadth of the surface of first outer surface  516  remains such that no part of fin  526  is in contact with the surface  532  of the surfboard.  
       Fourth Preferred Embodiment  
       [0089]     With reference to  FIGS. 22 and 23  in a fourth preferred embodiment of the invention, the right hand, centre and left hand fin boxes  600  are identical. The external configuration of fin boxes  600  is as previously described for the second and third preferred embodiments above, but the recess  608  is further simplified to a rectangular section recess with opposing parallel side and end walls, normal to the first outer surface  612 .  
         [0090]     In this embodiment each fin box is provided with a pair of angled threaded holes  617  at each side of recess  608 , and adapted to receive set screws  614  for the retention of one-piece fin-tabs  620 .  
         [0091]     The fin boxes of this embodiment are adapted for fin-tab configurations where the fin-tab is canted relative to the median plane of the fin for the right hand and left hand fins of a three fin arrangement.  
         [0000]     In Use  
         [0092]     The fin boxes of the present invention may be incorporated in the body of a surfboard in accordance with known processes. That is the board may be completely finished to the glassed stage, after which suitable recesses are machined through the glassed surface and into the foam of the core. The boxes are then inserted and retained with a suitable bonding agent. Alternatively, a cavity may be formed in the foam core and the box inserted prior to glassing. For this process the box may be provided with a projecting barrier  240  so as to prevent resin flowing into the recess  224  and angled threaded holes  234  and  235 .  
         [0093]     The above describes only some embodiments of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope and spirit of the present invention.