Bitts are paired vertical wooden or metal posts mounted either aboard a ship or on a wharf, pier or quay. The posts are used to secure mooring lines, ropes, hawsers, or cables. Bitts aboard wooden sailing ships (sometime called cable-bitts) were large vertical timbers mortised into the keel and used as the anchor cable attachment point. Bitts are carefully manufactured and maintained to avoid any sharp edges which might chafe and weaken the mooring lines.