Patent ID: 8393928

Claim:
A fin attachment structure for detachably attaching a fin to a bottom surface of a surfboard, the fin attachment structure comprising: a fin which includes a fin attachment base for attaching the fin to the bottom surface of the surfboard, wherein the fin attachment base includes fin nose and tail portions, and opposed side surfaces; a groove part having groove nose and tail portions formed on the bottom surface of the surfboard, wherein the groove part receives the fin attachment base portion when inserted therein; a pin provided across the groove nose portion of the groove part; at least one pair of opposed plungers located at both respective side surfaces of the groove part at the groove tail portion, wherein each of the plungers includes a ball part having a projection portion which projects outwardly therefrom; a hook slot formed in the attachment base portion of the fin for hooked engagement with the pin at the groove nose portion when the fin attachment base portion is inserted into the groove part; and recess portions formed on both of the side surfaces of the fin attachment base portion in positional correspondence to the projection portion of the ball part of a respective one of the plungers, wherein each of the recess portions receive the ball part of a respective one of the plungers when the fin attachment base portion is inserted into the groove part, wherein the hook slot is pivotally hooked around the pin at the groove nose portion of the groove part upon insertion of the fin attachment base portion into the groove part so that the fin attachment base portion is capable of freely rotating about the pin to thereby allow the fin to be sandwiched and held within the groove part by the plungers.