Water board fin provided with a hinge which is self-locking in a stabilizing position and a folded position

A fin intended for a navigation object, in particular an inflatable or rigid-shell water board, comprising a wing which is able to move with respect to a fastening base about an axis of rotation between a first stabilizing position and a second folded position, and rotation blocking means, for blocking the wing in the folded position, the axis of rotation being borne by two hinge components, one of which is fastened to the wing and the other to the fastening base, the hinge component fastened to the wing also being able to move translationally with respect to the hinge component fastened to the fastening base in order to unblock the wing, wherein the rotation blocking means are borne by the two hinge components in order to block the wing in the folded position and in the stabilizing position and in that it comprises an elastic means that deforms in compression or in bending, against the translational movement of the hinge component fastened to the wing, unblocking the wing from the stabilizing position.