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An anchor is an object, often made out of metal, that is 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 is quite possible the vessel cannot hoist it aboard but must hire a service to move or maintain it. Vessels carry one or more temporary anchors which may be of different designs and weights. A sea anchor is a related device used when the water depth makes using a mooring or temporary anchor impractical.
The vessel is attached to the anchor by the rode which is made with chain, cable or line or a combination of these. The hole in the hull through which the anchor rode passes is called "hawsepipe" because thick mooring lines are called "hawsers".
An anchor works by resisting the movement force of the vessel which is attached to it. There are two primary ways to do this—via sheer mass, and by "hooking" into the seabed. While permanent moorings can use large masses resting on this seabed this is not practical for temporary anchors which need to be stowed onboard so almost all temporary anchors are of the type which have metal flukes which hook on to rocks in the bottom or bury themselves in soft bottoms.