Here's a product that appears associated with this thread:

"The Anchor Saver is an anchor release system for stuck anchors, which varies slightly but significantly from old-style anchor retrieval systems. It utilises a unique Release Bar and Shackle mid-link connection, and is designed to separate the Release Bar from the Shackle, when the sheer pin breaks at a predetermined load. During the release, the attachment point shifts from the anchor Shank-Eye to the Crown-Eye, allowing the Anchor to be freed from the obstruction." See more at:

http://www.sail-world.com/index.cfm?...efre=y&ntid=30