Fins with improved fluid dynamic properties

Abstract

A fin for use on a surfboard, the fin comprising: a leading edge, a trailing edge, and a base, the base comprising at least one mount for mounting the fin onto a surfboard; a first and a second outer fin surface which meet along the leading edge and the trailing edge and abut the base; and a first ridge protruding laterally from the first outer fin surface, and/or a second ridge protruding laterally from the second outer fin surface; wherein the shape and configuration of the fin creates an area of lower water pressure around and in front of the fin, as well as disrupting and/or reducing the size of trailing vortices, resulting in additional forward thrust for the board on which the fin is mounted.

1 . A fin for use on a surfboard, the fin comprising:
 a leading edge, a trailing edge, and a base, the base comprising at least one mount for mounting the fin onto a surfboard;   a first and a second outer fin surface which meet along the leading edge and the trailing edge and abut the base; and   a first ridge protruding laterally from the first outer fin surface, and/or a second ridge protruding laterally from the second outer fin surface.   
     
     
         2 . A fin according to  claim 1 , wherein the first ridge protrudes laterally from the first outer fin surface, and/or the second ridge protrudes laterally from the second outer fin surface, to a maximum distance from the centreplane of between 1.5 to 6 times greater than the maximum distance of the centreplane to a non-ridged portion of the first outer fin surface, wherein the centreplane passes through the leading edge and trailing edge of the fin. 
     
     
         3 . A fin according to  claim 1 , wherein the first ridge protrudes laterally from the first outer fin surface, and/or the second ridge protrudes laterally from the second outer fin surface, to a maximum distance from the centreplane of between 3 to 3.5 times greater than the maximum distance of the centreplane to a non-ridged portion of the first outer fin surface, wherein the centreplane passes through the leading edge and trailing edge of the fin. 
     
     
         4 . A fin according to  claim 1 , wherein the first ridge and/or the second ridge are located adjacent the base. 
     
     
         5 . A fin according to  claim 1 , wherein the first ridge and the second ridge are located equidistant from the base. 
     
     
         6 . A fin according to  claim 1 , wherein the first ridge comprises a first ridgeline, and/or the second ridge comprises a second ridgeline, and the first and second ridgelines are on a plane substantially parallel to the base and/or the adjacent bottom surface of the surfboard to which the fin is mounted. 
     
     
         7 . A fin according to any  claim 6 , wherein the distance of the first ridgeline and/or the second ridgeline to the base is preferably between approximately 1% and 30% of the distance of the base to the tip of the fin. 
     
     
         8 . A fin according to  claim 6 , wherein the distance of the first ridgeline and/or the second ridgeline to the base is preferably between approximately 4% and 8% of the distance of the base to the tip of the fin. 
     
     
         9 . A fin according to  claim 1 , wherein the first ridge comprises first ridge sides, and/or the second ridge comprises second ridge sides, and at least a portion of the first ridge sides and/or second ridge sides comprise concave, convex, and/or flat portions. 
     
     
         10 . A fin according to  claim 6 , wherein the first ridgeline and/or second ridgeline end at the leading and/or trailing edge. 
     
     
         11 . A fin according to  claim 1 , wherein the fin comprises a third ridge protruding laterally from the first outer fin surface, and/or a fourth ridge protruding laterally from the second outer fin surface. 
     
     
         12 . A fin according to  claim 11 , wherein the third ridge and/or the fourth ridge are smaller and located further from the base than the first ridge and/or the second ridge. 
     
     
         13 . A fin according to  claim 11 , wherein the third and/or fourth ridges are on a plane that is substantially parallel to the base, and/or a plane that is substantially parallel to the adjacent bottom surface of the surfboard. 
     
     
         14 . A fin according to  claim 11 , wherein the third ridge protrudes laterally from the first outer fin surface, and/or the fourth ridge protrudes laterally from the second outer fin surface, to a maximum distance from the centreplane of between 1.5 to 6 times greater than the maximum distance of the centreplane to a non-ridged portion of the first outer fin surface, wherein the centreplane passes through the leading edge and trailing edge of the fin. 
     
     
         15 . A fin according to  claim 11 , wherein the third ridge protrudes laterally from the first outer fin surface, and/or the fourth ridge protrudes laterally from the second outer fin surface, to a maximum distance from the centreplane of between 3 to 4 times greater than the maximum distance of the centreplane to a non-ridged portion of the first outer fin surface, wherein the centreplane passes through the leading edge and trailing edge of the fin. 
     
     
         16 . A fin according to  claim 11 , wherein the third ridge comprises third ridge sides, and the fourth ridge comprises fourth ridge sides, and at least a portion of the third ridge sides and/or fourth ridge sides comprise concave, convex, and/or flat portions. 
     
     
         17 . A fin according to  claim 1 , wherein the fin is an adjustable fin comprising:
 a base comprising:
 a mount for attaching the fin to a surfboard; and 
 an insert member extending in a direction contrary to the mount; 
   a fin section comprising:
 two outer fin surfaces which meet at a leading edge and a trailing edge comprising the first and the second outer fin surfaces; 
 an underside surface comprising an opening to an internal cavity within the fin section, the internal cavity within the fin section configured to house the insert member of the base and enable slidable movement of the insert member in a direction towards the leading edge or the trailing edge; and 
 a lock that is manipulable, wherein the lock can releasably couple to the insert member at one of two or more locking positions thereby preventing slidable movement of the insert member; 
   wherein the fin section is configured to adjust relative to the base by manipulating the lock to uncouple the lock from the insert member at a first locking position, slidably moving the insert member through the internal cavity, and releasably coupling the lock to the insert member at a second locking position.   
     
     
         18 . A fin according to  claim 1 , wherein the fin is a detachable fin comprising:
 a base comprising:
 a mount for attaching the fin to a surfboard; and 
 an insert member extending in a direction contrary to the mount; 
   a fin section comprising:
 two outer fin surfaces which meet at a leading edge and a trailing edge comprising the first and the second outer fin surfaces; 
 an underside surface comprising an opening to an internal cavity within the fin section, the internal cavity within the fin section configured to house the insert member of the base; and 
 a lock that is manipulable, wherein the lock can releasably couple to the insert member thereby preventing movement of the fin section relative to the base; 
   wherein the fin section is uncoupled and detached from the base by manipulating the lock to uncouple the lock from the insert member.   
     
     
         19 . A fin according to  claim 1 , wherein the mount comprises one or more mounting blocks capable of attaching to commercially available fin plug and fin box systems, or a base attachment plate comprising a substantially flat base attachment surface which contacts the external bottom surface of a surfboard on to which it is mounted. 
     
     
         20 . A fin according to  claim 1 , for mounting to any one of the boards in the group comprising: surfboard, shortboard, kneeboard, longboard, minimal, soft board, kiteboard, wind surfer, stand up paddleboard, wakeboard, rescue board, bodyboard, or another board used in surface water sports or activities.