Patent Publication Number: US-9896168-B1

Title: Swing range adjustable fin assembly

Description:
BACKGROUND 
     The first surfboards were simple, substantially flat boards used for riding waves. Modern surfboards typically include one or more fins attached to the underside of the board which allow the surfer greater control over speed and trajectory. The size, shape, and angle of the fin or fins are significant factors in how the surfboard handles under various conditions. It is common for surfboards to be constructed with a standard finbox that allows the attachment and removal of fins having corresponding standard connectors. This allows the surfer to switch between fins having various properties depending on the conditions and the surfer&#39;s preferences. Among the properties that can be varied by fin selection is attack angle, which is the angle of the fin relative to the longitudinal axis of the surfboard. In some situations, performance could be improved by a fin capable of swinging through a range of attack angles during the course of a single ride. A fin that swings freely through all possible attack angles, however, would make the surfboard difficult to control and could be dangerous to the surfer. A surfboard fin capable of swinging through a variety of attack angles and yet having the attack angle sufficiently constricted to be useful does not appear to be provided by the prior art. 
     SUMMARY 
     The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements. 
     The teachings herein are directed to a surfboard fin assembly comprising a blade that engages a standard finbox, a base attached to the blade and having two pin guideways, and a rod extending down from the blade and connected to a fin which rotates about the rod. A fin stop pin is located in each pin guideway and projects out of the guideway into the path of rotation of the fin, blocking the fin from moving beyond the range of rotation set by the pin. 
     In one embodiment, the rod rotates with respect to the blade. In another embodiment, the fin rotates with respect to the rod. 
     In one embodiment, the pin guideways are channels in the base, to a void space defined in the base. In a further embodiment, the channels include a set of pin-fixation positions that hold a fin-stop pin at a specific location within the channel. 
     In one embodiment, the channels have a wide top and a narrow bottom, while the fin-stop pins have a wide base and a post. The base of a fin-stop pin fits into the wide top of the channel but cannot pass through the narrow bottom of the channel, such that the fin-stop pin is trapped within the channel but still able to slide along the channel. The post of the fin-stop pin projects thought the narrow bottom of the channel and into the path of rotation of the fin, blocking the fin from rotating past the location of the fin-stop pin. 
     The teachings herein are additionally directed to a surfboard comprising such a fin assembly. The surfboard defines a board plane that bisects the board between top and bottom along its greatest length and a fin plane that bisects the board along its length and is perpendicular to the board plane. 
     In one embodiment, the surfboard includes a fin port and the fin assembly includes a mating portion that fits into the fin port and secures the fin. A standard fin port is one form of a fin port. A blade is one form of a mating portion on a fin assembly that fits into a standard fin port. 
     In one embodiment, the fin-stop pins are independently adjustable. Adjustment of the fin-stop pins allows the fin to rotate up to 22.5 degrees relative to the fin plane. 
     In a further embodiment, the rod is tilted rearwardly relative to a line perpendicular to the board plane. 
     In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front-side-bottom isometric view of a surfboard with a fin assembly according to one preferred embodiment. 
         FIG. 2  is a detail view of the fin assembly of  FIG. 1 , showing a fin, a blade, a fin centering element and a pin guideway with a fin-stop pin engaged in one pin-fixation position. 
         FIG. 3  is a detail view of the fin assembly of  FIG. 1 , showing a pin guideway with a fin-stop pin engaged in one pin-fixation position. 
         FIG. 4  is a detail sectional view of the surfboard of  FIG. 1  showing the fin assembly secured to the surfboard via mating of the blade with the finbox. 
         FIG. 5  is a bottom view of the fin assembly of  FIG. 1 , showing a fin-stop pin engaged in the last pin-fixation position and the corresponding maximum rotation of the fin, as it abuts that fin-stop pin. 
         FIG. 6  is a bottom view of the fin assembly according of  FIG. 1 , showing a fin-stop pin engaged in the first pin-fixation position and the corresponding maximum rotation of the fin, as it abuts that fin-stop pin. 
         FIG. 7  is a detail view of a pin guideway and fin-stop pin of  FIG. 1 , showing the fin-stop pin in the last pin-fixation position. 
     
    
    
     Exemplary embodiments are illustrated in referenced drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Definition: As used in this application the term “surfboard” encompasses stand up paddle boards and other water recreation boards. 
     Referring to  FIG. 1 , in one embodiment a surfboard  10  is provided, having a fin assembly  12 . The fin assembly  12  includes a fin  14 , a base  16 , a fin centering element  17  and a blade  18 . The fin assembly  12  is removably attached to the bottom of the surfboard  10  such that the fin assembly is underwater when the surfboard is in use. Referring now to  FIG. 2 , in one embodiment the fin assembly base  16  is joined at a right angle to the blade  18 , which is shaped to mate with a standard surfboard finbox. A surfboard finbox is typically an insert that is permanently secured within a slot on the bottom of a surfboard and has means for removably securing a fin to the insert. As it is used in this application, a standard finbox is a finbox as described in US Patent Application Publication 2007/0202760. 
     The base  16  includes two void spaces  19 , each formed by an inward cut through a side surface of base  16 , in a dimension generally coincident with the plane of the base  16 . A pin guideway  20 , is formed by a channel cut into the base to the void space  19 . Other forms of pin guideway may also be used. 
     As shown in  FIGS. 3 and 7 , the fin-stop pin  22  has a wide base  24  and an attached post  26 . The pin guideway  20  has a wide top and a narrow bottom, such that the fin-stop pin base  24  fits into the wide top of the pin guideway but cannot pass through the narrow bottom of the pin guideway. The fin-stop pin post  26  fits through the narrow bottom of the pin guideway, protruding into the path of rotation of the fin. At one position along the pin guideway  20 , the narrow bottom of the pin guideway widens out to form a pin port  27  that allows the passage of the fin-stop base  24 , thereby allowing the fin-stop pin to be inserted or removed from the pin guideway  20 . In one embodiment, the pin port  27  is contiguous with both pin guideways, at the rear. 
     Referring now to  FIG. 4 , in one embodiment the fin assembly  12  comprises a fin  14 , a base  16 , and a blade  18 . A surfboard  10  is provided, having a standard finbox. The standard finbox comprises a recess in the body of the surfboard having means for attaching a surfboard fin having an appropriate connector. The blade  18  mates with the standard finbox to connect the fin assembly  12  to the surfboard  10 . When connected to the surfboard, the greatest length of the blade  18  is substantially parallel to the longitudinal axis of the surfboard. A rod  28  extends from the blade and is connected to the fin  14 . In one embodiment, the rod  28  is tilted toward the back of the surfboard. The attack angle of a surfboard fin is the angle of the plane of the fin relative to the longitudinal axis of the surfboard. The fin  14  rotates with respect to the blade  18 , allowing the attack angle of the fin to vary. The fin centering element  17 , which is elastomeric, urges fin  14  back to the center position. In one embodiment, fin  14  rotates with respect to the rod  28 . In an alternative embodiment, the rod  28  rotates with respect to the blade  18 . The fin-stop post  26  protrudes into the path of rotation of the fin  14 , preventing the fin from rotating past the location of the fin-stop post. 
     Referring now to  FIGS. 5 and 6 , in one embodiment, the base  16  comprises two pin guideways  20 , one on each side of the fin  14 . Along each pin guideway  20  are two or more pin-fixation positions  30 . In one embodiment, each pin-fixation position is a notch of sufficient width to admit the fin-stop post  26  ( FIGS. 2-4 and 7 ). In one embodiment, each pin-fixation position  30  includes means to retain the fin-stop post  26 , allowing the post to pass through only with the application of pressure. One means of retention is a narrowing at the entrance of the pin-fixation position  30 . As the fin-stop pin  22  is moved into a pin-fixation position  30 , the post  26  must pass through the narrower area. The narrowing is sized to allow the post  26  to pass through with the application of manual pressure but to prevent the post from passing through due to pressure caused by normal use of the fin assembly  12 . Each pin guideway  20  contains a fin-stop pin  22 , allowing the maximum rotation of the fin  14  in the clockwise and counter-clockwise directions to be independently controlled.  FIG. 5  shows one fin-stop pin  22  in the last pin-fixation position  30  and the fin  14  at the maximum clockwise rotation permitted by that pin-fixation position.  FIG. 6  shows one fin-stop pin  22  in the first pin-fixation position and the fin  14  at the maximum counter-clockwise rotation permitted by that pin-fixation position. It will be understood from  FIGS. 5 and 6  that each fin-stop pin  22  can be located at any pin-fixation position  30  along the pin guideway  20 , allowing the surfer to choose the appropriate pin-fixation position for the maximum amount of rotation desired. 
     In one embodiment, the entire assembly  10  (except for rod  28 ) is molded from ABS, a similar polymeric material or a type of fiberglass. In another embodiment, base  16  is made of a metal, such as a cast aluminum alloy or titanium, with the remainder, such as the fin  14  made of ABS, a similar polymer or fiberglass. 
     While a number of exemplary aspects and embodiments have been discussed above, those possessed of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.