Abstract:
A removable fin assembly with at least one suction cup for attaching to a small watercraft and a method for attaching a fin assembly using at least one suction cup to a small watercraft. The fin assembly removably attaches to the underside of a small watercraft with the fin extending downwardly. The fin assembly is made up of at least one suction cup, at least one distributor to spread out the forces across the suction cup or cups, and at least one fin. The fin can be a traditional fin, a hydrofoil keel, or something similar. An optional shell can be added around the attachment location to reduce drag. Recesses can be added to the distributor to help support the fin or reduce drag.

Description:
TECHNICAL FIELD 
     The apparatus described relates to small watercraft such as surfboards, standup paddle boards, wakeboards, kiteboards, kayaks, jet skis, and the like. In particular, it relates to a method and apparatus for removably attaching at least one fin to a small watercraft. 
     BACKGROUND OF THE INVENTION 
     Small watercraft often rely on a fin or a plurality of fins to provide horizontal lift or thrust to aid in tracking, steering, and stabilization of the watercraft. Some classes of fins also provide vertical lift to the watercraft. 
     A hydrofoil would be one example of a complex fin which provides vertical lift. Hydrofoils come in many shapes and designs but a common design for a hydrofoil intended for small watercraft comprises a keel attached to an optional longitudinal body and attached to at least one wing. Many different designs for hydrofoil wings and bodies exist but a keel is a commonality across many of these designs and is referred to as a hydrofoil keel. 
     Fins can be designed to be removable or non-removable from the watercraft. 
     Fins attached by a non-removable means cannot be interchanged between watercraft and the fin cannot be easily removed to aid in storage and transport of the watercraft. If damaged, non-removable fins can be expensive to repair since they are incorporated into the watercraft. Non-removable attachment could include attachment by molding or gluing the parts together. 
     Removable fins are common in watercraft such as surfboards and kiteboards, but these removable fins generally require the watercraft to be designed to incorporate the fin by means of a non-removable fin receptacle. Non-removable fin receptacles such as fin boxes, bolt holes, threaded holes, cavities, recesses, slots and the like are generally designed into the watercraft. These non-removable fin receptacles can limit the placement of fins on the watercraft and can limit the types of fins that are used. 
     It is common for water enthusiasts to own multiple watercraft. Users have long desired for there to be an easy method and apparatus to attach a removable fin to a watercraft and swap that same fin between watercraft even if the watercraft was not originally designed with the matching fin receptacle. For example, a surfer who already owns a surfboard without a hydrofoil keel receptacle cannot easily or non-destructively attach a hydrofoil keel to their existing surfboard. Likewise an inflatable standup paddle board owner cannot easily add a removable fin to their inflatable, board if′ the fin receptacle was not designed into the original board. 
     There are essentially four “groups” of related art that should be discussed in detail. 
     Group one depicts removable fins which rely on non-removable fin receptacles. Related art U.S. Pat. No. 8,246,406 to John Field depicts such an assembly. John Field&#39;s removable fin mates with a non-removable fin receptacle described as a “fin box”. Typically these fin boxes are incorporated into the watercraft and the fin box is not easily removable or easily adjustable. Also in this group is related art U.S. Pat. No. 7,108,571 B2 to Dean Geraghty. Dean Geraghty depicts a removable fin box which fits inside a recess or cavity on the watercraft. While Dean Geraghty&#39;s fin box is removable it shares similar limitations to non-removable fin boxes due to the use of a recess which is incorporated into the watercraft. The recess or cavity is effectively a non-removable receptacle. The location of the recess or cavity is not easily adjusted after the watercraft is manufactured. 
     Group two depicts fin box adapters. In this group, adapters are designed to allow removable fins to be used in more than one style of non-removable fin receptacles. Related art U.S. Pat. No. 5,176,553 to Lawrence Tuttle depicts such an assembly. Lawrence Tuttle&#39;s assembly allows a fin designed for a narrow and shallow fin receptacle to be used on a watercraft that has a wider and deeper fin receptacle. While Tuttle&#39;s assembly allows for a removable fin to be used on watercraft with different fin receptacles, it requires the watercraft to have a non-removable receptacle to mate with the receptacle. Similar to group one, the non-removable receptacle is incorporated into the watercraft. 
     Group three depicts adjustable fins. Related art U.S. Pat. No. 4,421,492 to Donn Leva depicts such an assembly. Donn Leva describes a non-removable fin receptacle which is essentially a slot incorporated into the watercraft. The fin attaches to the slot which allows the fin to slide forwards and backwards. While this slot allows for more adjustment than a standard fin box, the watercraft still incorporates a non-removable fin receptacle in the form of a slot which suffers from many of the same drawbacks described previously. 
     Group four depicts breakaway fins. Related U.S. Pat. No. 4,701,144 to Glen DeWitt depicts such an assembly. Glen Dewitt&#39;s fin incorporates a breakaway tab that allows the tin to separate from the watercraft in the event excessive force is exerted. This assembly incorporates a non-removable fin receptacle which suffers from many of the limitations of group one. Additionally, in this specific example, the retaining tab has to be replaced when the fin separates so the fin does not separate non-destructively. 
     Technical Problem 
     One problem with the related art described is that incorporating a fin or a fin receptacle into the body of the watercraft often requires additional manufacturing steps and can increase the cost of the watercraft. A second problem is that removable fins which attach to non-removable fin receptacles are typically not easily interchangeable between watercraft unless the different watercraft share receptacles that are designed to accept the same removable fin or if a fin adapter is used. Fin adapters are not universal and are often limited in the types of fins they can accommodate. A third problem is that fins, especially long fins like hydrofoil keels, are prone to striking objects in or beneath the water. The force exerted by a fin striking an object or even striking the surface of the water can damage the watercraft especially when the fin is firmly anchored to the watercraft. This potential damage mechanism can require additional reinforcement of the fin and the watercraft which can cost more during design and construction. A fourth problem is that if a removable fin separates from the watercraft while the watercraft is on the water, it can be difficult to quickly re-attach the fin. It is especially difficult to re-attach fins in sports like kitesurfing in which the user often has to use one hand to control their kite and only has one hand free for other tasks like re-attaching a fin to a watercraft. A fifth problem is that the placement of removable fins on a watercraft is often restricted by the location of the non-removable fin receptacle which can limit fine tuning of fin placement. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention addresses the problems above by providing a method and apparatus to easily attach and remove at least one fin and to swap the same fin assembly across many different types of watercraft even if the watercraft were not originally designed with a fin receptacle. The method and apparatus described allows the fin to break away from the watercraft in a non-destructive manner when the fin experiences excessive force, preventing damage to the fin and to the watercraft. The method and apparatus described allows a fin to be easily reattached to a watercraft in the event of separation without the need to replace parts. Additionally, because the fin attachment point is not limited to a non-removable fin receptacle, fin placement can be less restricted allowing the user to fine tune fin placement to their own preferences. The present invention is especially useful in attaching newer style fins including hydrofoil keels and the like to older style watercraft like traditional surfboards, kayaks, and the like which do not have receptacles for the newer style fins. This can save the user money because they can avoid buying a new board. The present invention is also especially useful for attaching removable fins to inflatable watercraft including inflatable rafts, inflatable stand up paddleboards and the like. The uses of the fin receptacle are not limited to the examples above. 
     A primary object of the present invention is to provide a removable fin assembly which overcomes the shortcomings of the related art. 
     A further object of the invention is to provide a removable fin assembly which can break away non-destructively when the fin experiences excessive force. 
     Another object of the invention is to provide a removable fin assembly which allows the user to fine tune fin placement on a watercraft. 
     Another object of the invention is to minimize drag associated with the removable fin assembly. 
     Another object of the invention is to make the fin assembly easy to retrieve when detached. 
     Further objects of the invention will appear as the description proceeds. To the accomplishment of the above and related objects, this invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific construction illustrated and described within the scope of the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various other objects, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
         FIG. 1  is an exploded perspective view of the preferred embodiment of the fin assembly with portions of the fin and watercraft broken away and configured with a long keel, similar to what would be found in a hydrofoil, and configured with an optional shell. 
         FIG. 2  is cross-section side view of the preferred embodiment of the fin assembly where the cross section is taken through the centerline of the watercraft. 
         FIG. 3  is a front view of the assembled preferred embodiment configured without the optional shell. 
         FIG. 4  is a front view of an alternative embodiment of the fin assembly configured with suction cups having adjustable connections to the distributor member and without a shell and where the suction cups are connected to a watercraft having a curved exterior. 
         FIG. 5  is a perspective view of an alternative embodiment of the distributor member configured with lever activated suction cups and without a shell. 
         FIG. 6  is a cross sectional view of the alternative embodiment of the distributor member of  FIG. 5 . 
         FIG. 7  is a bottom perspective view of an alternative embodiment of the fin assembly configured with an elongated suction cup, a vent port, a backflow prevention device, a traditional tin, and without a shell. 
         FIG. 8  is a cross-section side view of an alternative embodiment of the fin assembly where the cross section is taken through the centerline of the watercraft in  FIG. 7 . 
         FIG. 9  is a cross-section side view of an alternative embodiment of the distributor member configured with recesses on the suction side of the distributor member. 
         FIG. 10  is a perspective view of an alternative embodiment where the distributor member is attached to two elongated suction cups and the fin member is attached with side mount screws. 
         FIG. 11  is a perspective view of an alternative embodiment-here a single suction cup is used in conjunction with elastomeric bumpers. 
         FIG. 12  is an exploded perspective view of an alternative embodiment where more than one distributor members are used. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present invention. It will be understood by those of ordinary skill in the art that these embodiments of the present invention may be practiced without some of these specific details. In other instances, well-known methods, procedures, components and structures may not have been described in detail so as not to obscure the embodiments of the present invention. 
     Prior to explaining at least one embodiment of the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. 
     It is appreciated that certain features of the invention, which sue, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. 
     The preferred embodiment of the fin assembly  12  is illustrated in  FIG. 1  in an exploded perspective view. The fin member  11  and the watercraft  3  are broken away for illustration purposes. The watercraft  3  has a centerline  20 . The fin member  11  is attached to the fin side  14  of the distributor member  4  with screws  5  and further supported by an optional recess  6  in the raised face  8  of the distributor member  4 . The fin member  11  has a longitudinal axis  18  and a transverse axis  19  and the port side  17  is visible. The fin member  11  is shown as a keel type fin similar to what would be found in a typical hydrofoil keel. The distributor member  4  is configured with optional filleted edges  32 . The suction side  13  of the distributor member  4  is attached to the anti-cup side  16  of four suction cups  1  with screws  10  through tapped holes  2  in the suction cups  1 , untapped holes  7  in the distributor member  4 , and untapped holes  63  in the optional shell  9 . The optional shell  9  has walls bending upwardly from the perimeter of the distributor member  4 . The optional shell  9  is attached to the fin side  14  of the distributor member  4  with screws  10 . The cup sides  15  of the suction cups  1  are attached to the underside  33  of the watercraft  3  with suction force created by the suction cup. It will be understood by those of ordinary skill in the art that other standard attachment means could be used in place of the screwed attachments illustrated, it will be understood by those of ordinary skill in the art that a keel could further attach to various configurations of hydrofoil wings. In general, the distributor member  4  distributes the forces generated by the fin across the suction cups  1  but can serve other functions as well. 
     The preferred embodiment of the fin assembly  12  is further illustrated in  FIG. 2  in a non-exploded cross sectional side view where the cross section is taken through the centerline of the watercraft  3 . The watercraft  3  and the fin member  11  are broken away for illustration purposes. This view further illustrates the optional shell  9  bending upwardly and terminating as close as possible to the underside  33  of the watercraft  3 . 
     The preferred embodiment of the fin assembly  12  is further illustrated in  FIG. 3  in a non-exploded front view configured without shell  9  of  FIG. 1  and  FIG. 2 .  FIG. 3  shows the watercraft  3  and fin member  11  broken away for illustration purposes. This view further illustrates the transverse axis  19  of the fin member  11  which runs between the port side  17  and the starboard side  34 . 
     An alternative embodiment of the fin assembly  36  is illustrated in  FIG. 4  in a non-exploded front view. This embodiment shares many of the components of the preferred embodiment with the primary change being that the screws  10  of  FIG. 3  have been substituted for ball joints  35  to demonstrate attaching the alternative embodiment of the fin assembly  36  to the curved underside  37  of a watercraft  38 .  FIG. 4  shows the suction cups  1  attached to the suction side  13  of the distributor member  4  with a ball joint  35 . It will be understood by those of ordinary skill in the art that other standard movable attachment means could be used in place of the ball joint illustrated. 
     An alternative embodiment of the distributor member  65  is illustrated in  FIG. 5  in a partially exploded perspective view without a fin member attached. In this embodiment, the suction cups  66  are lever activated where the suction cup  66  is attached to a shaft member  67  which is attached to a lever member  68  with a small pin or hinge  69 . Each lever activated suction cup is set in a recess  70  on the suction side  71  of the distributor member  65 . When activated the lever member  68  pulls the shaft member  67  and the suction cup  66  into the recess creating a suction force.  FIG. 6  is a cross sectional side view taken along line A-A of  FIG. 5 .  FIG. 6  further illustrates the alternative embodiment of the distributor member  65 .  FIG. 6  shows both an activated and a non-activated suction cup  66 . 
     A different embodiment of the fin assembly  45  is illustrated in  FIG. 7  in a non-exploded bottom oriented perspective view with the underside  46  of the watercraft  30  facing up. In this embodiment, a singular elongated suction cup  27  contains a vent port  21 . A backflow prevention device  22  is mounted inside the vent port  21 . The backflow prevention device  22  is oriented such that fluid flow through the backflow prevention device  22  can flow from the interior wall  49  of  FIG. 8  to the exterior wall  50  but fluid flow is limited in the reverse direction. The exterior wall  47  of the elongated suction cup  27  is visible. The cup side  29  of the elongated suction cup  27  is attached to the underside  46  of the watercraft  30  with suction force. The anti-cup side  28  of the elongated suction cup  27  is attached to the distributor member  25  with screws  26 . The screws are shown in a loosened state for illustrative purposes. It will be understood by those of ordinary skill in the art that other standard attachment means could be used in lieu of the screwed attachments illustrated. It will also be understood by those of ordinary skill in the art that the backflow prevention device could be selected from a number of common designs such as diaphragm check valves, flapper check valves, and the like. In this embodiment, the fin member  23  is non-removably attached to the fin side  31  of the distributor member  25 . The fin member  23  is illustrated as a traditional surf fin. The starboard side  24  of the fin member  23  is visible. The watercraft  30  has a centerline  48 . The fin assembly  45  is shown centered on the board for illustrative purposes. It will be understood that the suction mechanism could allow the user to place the fin assembly off center if desired. 
     The embodiment of the fin assembly  45  of  FIG. 7  is further illustrated in  FIG. 8  in a non-exploded cross-sectional side view where the cross section is taken down the centerline  48  of the watercraft  30  of  FIG. 8  and the underside  46  of the watercraft  30  is facing down. In  FIG. 8  the interior wall  49  and the exterior wall  50  of the elongated suction cup  27  are shown. The vent port  21  is shown to tunnel from the exterior wall  50  to the interior wall  49 . The backflow prevention device  22  of  FIG. 7  is excluded from the vent port in this view for illustrative purposes. The screws  26  are shown in their fastened state. 
     Another embodiment of the fin assembly  51  is illustrated in  FIG. 9  in a cross sectional side view similar to  FIG. 2 . This embodiment shares many features with the preferred embodiment such as the shell  9  suction cups  1 , screws  10 , watercraft  3 , centerline  20 , longitudinal axis  18 , and fin member  11 . In this embodiment, the fin member  11  is non-removably attached by means of a weld  57  to the fin side  54  of the distributor member  53 . It will be understood by those of ordinary skill in the art that other non-removable attachment means could be used in place of a weld. The suction cups  1  mate with the distributor member  53  at recesses  52  which are located on the suction side  56  of the distributor member  53  and the suction cups  1  are attached by screws  10 . 
     A different embodiment of the fin assembly  39  is illustrated in  FIG. 10  in an exploded perspective view. This embodiment shares many features of the preferred embodiment with the primary differences being that two elongated suction cups  40  are used in place of the four suction cups  1  of  FIG. 1 , and side mount screws  41  are used to attach the fin member  11  to the distributor member  4  in place of screws  5  of  FIG. 1 . In this embodiment the fin member  11  is held in place by friction and compression with the side mount screws  41  which can be tightened against the port side  17  of the fin member  11  once the fin member  11  has been inserted into the recess  6 . The elongated suction cups  40  have a cup side  42  and an anti-cup side  43 . The elongated suction cups  40  have tapped holes  44  for attachment with screws  10 . It will be understood by those of ordinary skill in the art that other standard attachment means could be used in place of the screwed attachments illustrated. 
     A different embodiment of the fin assembly  55  is illustrated in  FIG. 11  in an exploded top oriented perspective view. This embodiment shares many features of the preferred embodiment such as the fin member  11 , screws  5 , distributor member  4 , shell  9 , and untapped holes  7 . In this embodiment, a single suction cup  58  is attached to the center of the suction side  13  of the distributor member  4  with a threaded element  59 . The threaded element  59  is non-removably attached to the distributor member  4  in this embodiment such as by welding. Elastomeric bumpers  60  are attached to the suction side  13  of the distributor member  4  with screws  61 . Screws  61  extend through holes  7  and holes  63  and are attached to nuts  62 . The port side  17  of the fin member  11  is visible. The cup side  64  of the suction cup  58  is facing up. It will be understood by those of ordinary skill in the art that other standard attachment means could be used in place of the screwed and nutted and welded attachments illustrated. 
     Another alternative embodiment of the fin assembly  72  is depicted in  FIG. 12 . This embodiment shares many features of the preferred embodiment such as the fin member  11 , screws  5 , shell  9 , screws  10 , and suction cups  1 . The primary difference is that the fin member  11  in this embodiment is attached to more than one distributor member. The forward distributor member  74  and the rear distributor member  73  each being attached to a pair of suction cups  1 .