An anchor for anchoring a vessel to an underwater structure. The anchor includes a shaft and at least three inexpensive flukes each attached to the shaft with a tension adjustable release mechanism. In use at least one of the inexpensive flukes grapple onto a portion of the structure securing the vessel in place. If sufficient tension is applied to the anchor line connecting the anchor to the vessel the release mechanism releases the inexpensive fluke to free the anchor without damage to the underwater structure. In a preferred embodiment each of the release mechanisms includes a spring and a threaded bolt for placing the spring in compression by compressing the spring between the head of the bolt and a first end of a rod into which the bolt is screwed. The rod is contained within a tube. A tab on the inexpensive fluke fits into a slot at the second end of the rod and the tab is trapped in the slot by the inside surface of the tube. The fluke is released if sufficient tension is applied to the fluke to first overcome the compressive force applied by the bolt on the spring and second to extend the rod far enough outside the tube so that the tab on the fluke is no longer trapped by the inside surface of the tube. In a preferred embodiment the tension required for release can be adjusted from about 20 pounds to about 1000 pounds.