Abstract: An anchor comprises an anchor shaft member and an anchor body member in the form of a plate having two blades which are joined to the anchor shaft member by a pivotal connection which allows the blades to lie normally within a range of angles to the plane containing the anchor shaft and the pivot axis. This range of angles is determined by the interconnection between two lugs on the anchor body member projecting away from the pivot axis on the opposite side from the main plate constituting the anchor shaft to enable the anchor to lodge against the submarine obstruction in the usual way: the relative inclination of the anchor body member and the anchor shaft member can be changed by applying a force greater than that required to effect shearing of the shear pin so that the anchor shaft member can swing freely about the pivot with respect to the blade to allow release of the anchor.