To provide a fin structure of a surfboard capable of constituting a surface agreeing with a bottom surface when fitting a fin box to the board, reliably mounting the fin, and preventing detachment or breakage of the fin when receiving the water resistance, in regard to the fin by an extensive surface.
The fin structure comprises a fin 1 having a fin body 10 used for a surfboard, a mounting base part 11, and a tongue piece part 12 continuously provided on the mounting base part, and a fin box 2 having a cavity part including an insertion part 22 capable of accommodating the fin mounting base part and the tongue piece part into a casing. The fin structure has a surface constituted of parallel inclined ridges 220-223 with a side ridge of the tongue piece part of the fin is inclined from the forward direction to the backward direction of the fin, and a surface constituted of an inclined ridge in which a side ridge of the insertion part for inserting the tongue piece part of the fin of the fin box is agreed with the angle of inclination of the inclined ridge of the tongue piece part.
KUMANO KATSUYOSHI
ONUKI TOMOHIRO
KUMANO KATSUYOSHI
ONUKI TOMOHIRO
High Koichi Hashi
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