An anchor is an object, often made out of metal, that's used to attach a ship to the bottom of a body of water at a specific point. There are two primary classes of anchors—temporary and permanent. A permanent anchor is often called a mooring, and is rarely moved; it's quite possible the vessel can't hoist it aboard but must hire a service to move or maintain it. A temporary anchor is usually carried by the vessel, and hoisted aboard whenever the vessel is in motion, hence the term "unde… (More on Anchors)