Abstract:
A surfing craft with removable fin. A removable fin is disposed in a fin box and the fin box is disposed in a surfing craft body. A releasable locking mechanism has a spring actuated locking arm, a locking tab and an indention. The spring actuated locking arm applies spring force for locking the locking tab into the indention. A counter force is applied to the spring actuated locking arm to remove the fin from the fin box. In one preferred embodiment, the locking tab is attached to the locking arm and the locking arm is bendably connected to the fin. In this preferred embodiment the indention is on the fin box and the locking arm&#39;s locking tab is engaged with the indention of the fin box to prevent the fin from disconnecting from the fin box. Also in this preferred embodiment, by applying finger force the locking arm is bent causing the locking tab to disengage the indention so that the fin can be removed.

Description:
BACKGROUND OF THE INVENTION 
     Surfing is an extremely old sport. Lieutenant James King, serving under Captain James Cook during his third expedition to the Pacific, in 1779 wrote what is recognized as the first known written description of the surfing ever recorded by Western man. Referring to the locals at Kealakekua Bay on the Kona coast of the Big Island of Hawaii, King writes: 
     Whenever, from stormy weather, or any extraordinary swell at sea, the impetuosity of the surf is increased to its utmost heights, they choose that time for this amusement: twenty or thirty of the natives, taking each a long narrow board, rounded at the ends, set out together from the shore. . . . As the surf consists of a number of waves, of which every third is remarked to be always much larger than the others, and to flow higher on the shore, the rest breaking in the intermediate space, their first object is to place themselves on the summit of the largest surge, by which they are driven along with amazing rapidity toward the shore. 
     Since the time of the ancient Hawaiians, surfing has evolved considerably. While the Hawaiians rode wooden surfboards that could weigh as much as 175 pounds, in contrast, modern surfboards are much smaller, lighter and more maneuverable. 
     Modern surfboards are rarely made of solid wood. Instead, a modern surfboard is usually made of shaped and sanded foam that has been covered with one or more layers of fiberglass. For example, FIG. 1 shows a typical prior art modern surfboard  10 . A body of shaped plastic foamed material  11  is covered with a layer of fiber-reinforced resin  12 , preferably fiberglass, and has one or more fins which are supported in a rectangular box called a fin box. On some surfboards, the fins are “glassed on” for support. 
     Method of Fin Attachment 
     Glassing the Fins 
     Glassing the fins onto a surfboard refers to the act of attaching the fins to the board by means of a fiber-reinforced resin around the base of the fin. There are significant disadvantages to glassing the fins onto the surfboard. Labor costs can be high and subsequent sanding and finishing of the board can be difficult. Also, once the fin is glassed on, it cannot be adjusted or replaced. Hence, transporting a surfboard with glassed on fins can be difficult. For example, if the fin is bumped or hit it can break off or crack the fiberglass, ruining the whole surfboard. 
     Fin Boxes 
     In the use of the fin box, a rectangular cavity is formed in the board by the use of a router and the fin box is inserted into this cavity. FIG. 2 shows a side cross section view of fin box  14  shown in FIG.  1 . Fin box  14  is initially secured inside the cavity in foamed material  11  by an adhesive and then further secured by fiber-reinforced resin layer  12 . Fin  13  is inserted inside fin box  14  and secured into fin box  14  by means of screw  15 . To remove fin  13  from fin box  14 , the surfer has to unscrew screw  15  with a screwdriver. 
     There are significant disadvantages to prior art fin boxes. For example, the screw can corrode due to long term exposure to salt water. Or the screw can loosen over time, allowing the fin to fall out and become lost. Also, because a tool is required to remove the fin, a surfer who does not have a screwdriver with him will be unable to remove his fin. 
     Whereas ancient Hawaiians surfed primarily for pleasure or social status, modern surfing can be extremely competitive. Surfing competitions are held throughout the world with world wide television coverage and large cash prizes. Also, valuable endorsement contracts are rewarded to the best surfers. 
     Competitive surfers are looking for an advantage over the field to increase their odds of winning. The board and fin types chosen by the surfer are very important. Based on the wave conditions, one type of fin may be preferable over another type. Currently, it is difficult for the surfer to quickly switch fins. He is forced to find a screwdriver, unscrew the current fin, and screw in the new fin. 
     What is needed is a better way of mounting fins into a fin box. 
     SUMMARY OF THE INVENTION 
     The present invention provides a surfing craft with removable fin. A removable fin is disposed in a fin box and the fin box is disposed in a surfing craft body. A releasable locking mechanism has a spring actuated locking arm, a locking tab and an indention. The spring actuated locking arm applies spring force for locking the locking tab into the indention. A counter force is applied to the spring actuated locking arm to remove the fin from the fin box. In one preferred embodiment, the locking tab is attached to the locking arm and the locking arm is bendably connected to the fin. In this preferred embodiment the indention is on the fin box and the locking arm&#39;s locking tab is engaged with the indention of the fin box to prevent the fin from disconnecting from the fin box. Also in this preferred embodiment, by applying finger force the locking arm is bent causing the locking tab to disengage the indention so that the fin can be removed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a prior art surfboard. 
     FIG. 2 shows details of the fin box of the prior art surfboard of FIG.  1 . 
     FIGS. 3A-5B show a sequence depicting the installation of a preferred fin box into the body of a preferred surfboard. 
     FIG. 6 shows a perspective view of a preferred embodiment of the present invention. 
     FIGS. 7-11 show a sequence depicting the attachment of a preferred fin to a preferred fin box. 
     FIGS. 12-14 show a sequence depicting the removal of a preferred fin from a preferred fin box. 
     FIGS. 15-16 show another preferred embodiment. 
     FIGS. 17-18 show another preferred embodiment. 
     FIGS. 19-20 show another preferred embodiment. 
     FIGS. 21-24 show another preferred embodiment. 
     FIG. 25 shows another preferred embodiment of the present invention. 
     FIG. 26 shows a preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Preferred Embodiment 
     FIG. 6 shows a perspective view and FIG. 7 shows a side view of surfboard fin  1  positioned over fin box  2 . Preferably, fin box  2  has upper portion  8  and tab  7 . Tab  7  functions to secure fin box  2  inside the surfboard&#39;s foam material. In the preferred embodiment, fin  1  is inserted into fin box  2  by inserting base  20  into cavity  9 . FIG. 7 shows a cross section side view of cavity  9 . Tongue portion  24  is first inserted into socket  25 , then the opposite end of base  20  is pressed into cavity  9 . Inserting fin  1  into fin box  2  causes flexible locking arm  21  to bend towards base  20  until spring force snaps locking tab  22  back into a locked position in indention  23 . Once inserted, the upper edge of locking tab  22  rests flush under overhanging edge  33  of indention  23  to prevent fin  1  from falling out of fin box  2 . To remove fin  1  from fin box  2 , the surfer merely presses against the upper portion of locking arm  21  with his finger. This counter force causes locking arm  21  to bend and locking tab  22  to clear edge  33 . The surfer can then easily pull upward on fin  1  to remove it from fin box  2 . By utilization of the present invention, a surfing fin can be inserted and removed quickly and easily from its fin box without the use of any tools other than the surfer&#39;s own hands. 
     Mounting the Fin Box into the Surfboard 
     FIGS. 3A-5B show a preferred method for mounting fin box  2  into a surfboard. 
     FIG. 3A shows a side view of a preferred fin box  2  positioned over shaped plastic foam material  3 . Preferably, plastic foam material  3  has been shaped and sanded into the form of a surfboard, such as that depicted in FIG.  1 . Fiberglass layers  5  and  6  have been applied. FIG. 3A also shows a cross section side view of cavity  4 . Cavity  4  has been cut by the use of a router to conform to the shape of fin box  2 . FIG. 3B shows a cross section front view that corresponds to the side view depicted in FIG.  3 A. 
     FIGS. 4A and 4B show fin box  2  inserted into cavity  4  (FIGS.  3 A and  3 B). Preferably, fin box  2  is secured inside cavity  4  with an adhesive. 
     FIGS. 5A and 5B show the bottom portion of tab  7  sanded so that it is approximately flush with the bottom of fiberglass layer  6 . 
     Inserting the Fin into the Fin Box 
     FIGS. 7-11 show a sequence illustrating how fin  1  is inserted inside fin box  2 . 
     In FIG. 7, fin  1  is positioned over cavity  9  of fin box  2 . 
     In FIG. 8, base portion  20  of fin  1  has been inserted inside cavity  9  at an angle. Tongue  24  has been inserted into socket  25 . 
     In FIG. 9, fin  1  has been lowered further into cavity  9  so that locking tab  22  is in contact with edge of ramp  26 . A perspective view of ramp  26  is shown in FIG.  6 . 
     In FIG. 10, fin  1  has been lowered further into cavity  9 . Locking tab  22  pressing against lip  53  has caused locking arm  21  to bend, allowing for further downward movement of fin  1 . In the first preferred embodiment, base  20  is made out of a fiberglass reinforced composite plastic. Fiberglass reinforced composite plastic is a material that is strong enough to provide good support for fin  1 , yet ductile so that locking arm  21  can be bent by applying finger force to its upper portion (see also FIG.  12 ). 
     In FIG. 11, base  20  of fin  1  is fully inserted into fin box  2 . The bending of locking arm  21  (shown in FIG. 10) creates a spring force. The spring force causes locking arm  21  to snap back to its upright position after locking tab  22  clears lip  53 . The upper edge of locking tab  22  rests flush against the upper horizontal edge of grove  23  to prevent fin  1  from moving upward, thereby firmly securing fin  1  inside fin box  2 . In the first preferred embodiment, unwanted lateral motion is resisted by the mating of tongue  24  with socket  25 , the abutment of locking arm  21  against lips  43  and  53 , and by the abutment of base  20  against edge  91  of fin box  2 . 
     Removing the Fin from the Fin Box 
     FIGS. 12-14 show a sequence illustrating how fin  1  is removed from fin box  2 . 
     In FIG. 12, the surfer has overcome the spring force by the application of a counter force to locking arm  21 . He has slid his finger along ramp  26  and has pressed locking arm  21  so that it bends, allowing for upward movement of fin  1 . 
     In FIG. 13, fin  1  has been lifted up at an angle. Lip  53  is pressing against locking tab  22  so that locking arm  21  is still bent. 
     In FIG. 14, fin  1  has been lifted further upward at an angle. The surfer may now completely remove the fin from the fin box so that it is in the position shown in FIGS. 6 and 7. 
     Second Preferred Embodiment 
     A second preferred embodiment is shown in FIGS. 15 and 16. In the second preferred embodiment, locking arm  60  is connected to fin box  61 . Fin  63  is installed in a fashion similar to that described above in reference to the first preferred embodiment. As fin  63  is lowered into fin box  61 , locking arm  60  bends allowing fin  63  to be inserted inside fin box  61 . 
     In FIG. 15, fin  63  is fully inserted inside fin box  61 . Locking arm  60  has snapped back to its upright position. The lower horizontal edge of locking tab  65  is adjacent the horizontal edge indention  66  to prevent fin  63  from moving upward, thereby firmly securing fin  63  inside fin box  61 . 
     In FIG. 16, the surfer has bent locking arm  60  by pressing against its upper portion with his finger. Locking tab  65  has been cleared from indention  66 , enabling the surfer to remove the fin. 
     Third Preferred Embodiment 
     A third preferred embodiment is shown in FIGS. 17 and 18. In the third preferred embodiment, locking arm  70  is connected to fin  73 . Fin  73  is installed in a fashion similar to that described above for the earlier preferred embodiments. As fin  73  is lowered into fin box  71 , locking arm  70  bends allowing fin  73  to be inserted inside fin box  71 . 
     In FIG. 17, fin  73  is fully inserted inside fin box  71 . Locking arm  70  has snapped back to its upright position. The lower horizontal edge of locking tab  75  is adjacent the horizontal edge of indention  76  to prevent fin  73  from moving upward, thereby firmly securing fin  73  inside fin box  71 . 
     In FIG. 18, the surfer has bent locking arm  70  by pressing against its upper portion with his finger. Indention  76  has been cleared from locking tab  75 , enabling the surfer to remove the fin. 
     Fourth Preferred Embodiment 
     A fourth preferred embodiment is shown in FIGS. 19 and 20. In the fourth preferred embodiment, locking arm  80  is connected to fin box  81 . Fin  83  is installed in a fashion similar to that described above for the earlier preferred embodiments. As fin  83  is lowered into fin box  81 , locking arm  80  bends allowing fin  83  to be inserted inside fin box  81 . 
     In FIG. 19, fin  83  is fully inserted inside fin box  81 . Locking arm  80  has snapped back to its upright position. The upper horizontal edge of locking tab  85  is adjacent the horizontal edge of indention  86  to prevent fin  83  from moving upward, thereby firmly securing fin  83  inside fin box  81 . 
     In FIG. 20, the surfer has bent locking arm  80  by pressing against its upper portion with his finger. Indention  86  has been cleared from locking tab  85 , enabling the surfer to remove the fin. 
     Fifth Preferred Embodiment 
     Although each of the above preferred embodiments disclosed a locking arm that could be bent by apply finger force pressure, it would also be possible to have other types of locking arms. For example, in another preferred embodiment shown in FIGS. 21-24, locking arm  121  is pivotally attached to the base  120 . Spring  128  urges clockwise rotation of locking arm  121 . 
     In FIG. 21, fin  150  is positioned above base  151 . 
     In FIG. 22, base portion  120  of fin  150  has been inserted inside fin box  151  at an angle. Tongue  124  has been inserted into socket  125 . Locking tab  122  pressing against lip  125  has caused locking arm  121  to rotate counterclockwise and has expanded spring  128 . 
     In FIG. 23, base  120  of fin  150  is fully inserted into fin box  151 . Spring  128  has snapped locking arm  121  to an upright position. The upper edge of locking tab  122  rests flush against the upper horizontal edge of grove  130  to prevent fin  150  from moving upward, thereby firmly securing fin  150  inside fin box  151 . 
     In FIG. 24, the surfer has pressed the upper portion of locking arm  121  with his finger. Locking tab  122  has been cleared from indention  130 , enabling the surfer to remove the fin. 
     Although the above-preferred embodiments have been described with specificity, persons skilled in this art will recognize that many changes to the specific embodiments disclosed above could be made without departing from the spirit of the invention. For example, although specific fin boxes were shown in the above discussed preferred embodiments, it would be possible to utilize a variety of other fin boxes other than the fin boxes shown. For example, it would be possible to make fin box  2  without tab  7 . Also, although the above-preferred embodiments discussed a “surfer” removing and installing the fin inside the fin box, other individuals besides a surfer would benefit from the present invention. For example, individuals who sale surfboards and individuals who transport surfboards would find the present invention very useful. Also, the present invention can be utilized on surfing crafts other than surfboards. For example, it could be utilized on other surfing crafts in which fins are attached (such as a wind surfer). Wind surfers have, in addition to the board and at least one fin., a mast and sail that the rider can manipulate for propulsion. Also, although the above preferred embodiments disclosed using finger force to bend the locking arm, it would be possible to bend the locking arm with other objects besides a finger. For example, as locking arm  21  is made more rigid, the amount of force necessary to bend it becomes greater. For a very rigid locking arm  21  (FIG.  6 ), or for a very tight spring  128  (FIGS.  21 - 24 ), a hand tool (for example, a rock with a flat edge) could be used to apply force directly to the locking arm. Also, although FIG. 6 shows locking arm  21  attached to base  20  at leading edge  300  of fin  1 , it would also be possible to attach the locking arm to the trailing edge. For example, FIG. 25 shows locking arm  210  attached to base  260  at trailing edge  200  of fin  250 . Also, the present invention can be used on surfing craft having just one fin or on a surfing craft having multiple fins. For example, FIG. 26 shows surfboard  133  having three fins  1  inserted in three fin boxes  2 . Therefore, the attached claims and their legal equivalents should determine the scope of the invention.