Fin attachment structure and fin

Abstract

To provide a fin attachment structure capable of attaching a fin detachably and easily on a board without using any tools, and particularly, to a fin attachment structure capable of reducing the damage to human body as much as possible when the fin comes into contact with the human body during surfing etc. and having an extremely high safety, and a fin. The above problem can be solved by a fin attachment structure and a fin, in which a groove part is provided on the bottom surface of the surfboard and a hollow part 10 is provided on the inner surface thereof, the hollow parts being further provided at the opposing positions on both side surfaces of the groove part, and an elastic member is provided at the deep side within the hollow part and a bail part at the opening side for biasing in the direction in which it projects to outside, wherein by the insertion of the fin attachment base portion into the groove part, the fin is biased and sandwiched and held by the ball part.

1 . A fin attachment structure, which is a fin attachment mechanism for attaching a fin detachably to a bottom surface of a surfboard, comprising:
 a groove part  1  into which a fin attachment base portion  51  is inserted on the bottom surface of the surfboard and a hollow part  10  on the inner surface of the groove part  1 , the hollow parts  10  being provided at the opposing positions on both side surfaces of the groove part  1 , respectively; and   an elastic member  2  at the deep side within the hollow part  10  and a ball part  3  at the opening side, the ball part  3  being biased by the elastic member  2  from the opening within the hollow part  10  in the direction in which it projects to outside, wherein   by the insertion of the fin attachment base portion  51  into the groove part  1 , the ball parts  3  within the hollow parts  10  provided on both sides of the groove part  1  is moved into the hollow part  10  against the biasing of the elastic member  2  and thereby the fin  5  is biased and sandwiched and held by the ball part  3 .   
   
   
       2 . The fin attachment structure according to  claim 1 , wherein
 the elastic member  2  is a coil spring.   
   
   
       3 . The fin attachment structure according to  claim 1 , wherein
 the ball part  3  is configured by a spherical body.   
   
   
       4 . The fin attachment structure according to  claim 1 , wherein
 the length in the lengthwise direction of the groove part  1  of the surfboard is longer than that in the lengthwise direction of the fin attachment base portion  51 .   
   
   
       5 . The fin attachment structure according to  claim 1 , wherein
 the hollow parts  10  are provided at two portions in the front direction and in the rear direction of the groove part  1  and at the same time, also provided at opposing positions on both side surfaces of the groove part  1 , respectively; and   by the insertion of the fin attachment base portion  51  into the groove part  1 , the ball parts  3  within the hollow parts  10  provided on both sides at two portions in the front direction and in the rear direction of the groove part  1 , respectively, are moved into the hollow part  10  against the biasing of the elastic member  2  and thereby the fin  5  is biased and sandwiched and held by the ball parts  3 .   
   
   
       6 . The fin attachment structure according to  claim 1 , wherein
 the groove part  1  is provided in a fin box and the fin box is mounted on the bottom surface of the surfboard.   
   
   
       7 . A fin used in a fin attachment structure according to  claim 1 , wherein
 a fin attachment base portion  51  has a recess portion  52  corresponding to a projected surface of the ball part  3  respectively on both side surfaces of the fin  5  located at the ball part  3  when the fin  5  is mounted in the groove part  1 .   
   
   
       8 . A fin used in the fin attachment structure according to  claim 1 , wherein
 either or both of corner portions in the front direction and in the rear direction of the fin attachment base portion  51  are configured by an inclined side part  53 .   
   
   
       9 . The fin according to  claim 8 , wherein
 instead of the inclined side part  53 , an arc side part is used.