Self-adjusting board fin

Abstract

An adjusting fin for a watercraft consisting of a fin removably attached to a spindle that is held within a fin box. The spindle is rotatable within the fin box such that the fin can pivot with action of water against the fin as the watercraft moves through the water. Adjustable stops act against cams on the spindle to limit the range of rotation available, thus allowing the adjusting fin to be set up to suit the prevailing conditions and the expertise of the user. An optional biasing means biases the fin towards a neutral position which is perpendicular to an underside of the watercraft.

1 . An adjusting fin comprising: 
 (a) a fin box fixable to a watercraft;    (b) a spindle seated in the fin box for rotation about a longitudinal axis of the spindle;    (c) a fin associated with the spindle so as to pivot relative to the watercraft with rotation of the spindle;    (d) at least one cam associated with said spindle;    (e) at least one cam engaging stop adjustable to restrict the extent of rotation of the spindle, and thus limit the degree of pivot of the fin; and    (f) a biasing means that biases the fin towards a neutral position.    
     
     
         2 . (canceled)  
     
     
         3 . The adjusting fin of  claim 2  wherein the biasing means acts upon the spindle.  
     
     
         4 . The adjusting fin of  claim 2  wherein the biasing means acts upon the cam of the spindle.  
     
     
         5 . The adjusting fin of  claim 2  wherein the biasing means is a spring.  
     
     
         6 . The adjusting fin of  claim 1  wherein the fin box comprises a base and a detachable cover and wherein the spindle is retained between the base and cover.  
     
     
         7 . The adjusting fin of  claim 1  wherein the fin is removably attached to the spindle.  
     
     
         8 . The adjusting fin of  claim 1  wherein the position of the fin relative to the spindle is adjustable for fine trimming of the watercraft.  
     
     
         9 . The adjusting fin of  claim 1  wherein the cam engaging stop is a grub screw.  
     
     
         10 . A watercraft including an adjusting fin, said adjusting fin comprising: 
 (a) a fin box fixed to the watercraft;    (b) a spindle seated in the fin box for rotation about a longitudinal axis of the spindle;    (c) a fin removably attached to the spindle so as to pivot relative to the watercraft with rotation of the spindle;    (d) at least one cam associated with said spindle;    (e) at least one cam engaging stop adjustable to restrict the extent of rotation of the spindle, and thus limit the degree of pivot of the fin; and    (f) a biasing means that biases the fin towards a neutral position.    
     
     
         11 . (canceled)  
     
     
         12 . A fin box assembly comprising: 
 (a) a base for fixing in a surfboard;    (b) a spindle seated in the base for rotation about a longitudinal axis of the spindle;    (c) at least one cam associated with said spindle;    (d) at least one cam engaging stop adjustable to restrict the extent of rotation of the spindle;    (e) a removable cover retaining the spindle in the base; and    (f) a biasing means that biases the spindle towards a neutral position.    
     
     
         13 . (canceled)