What is a graving dock?

   A graving dock, or dry dock, is an artificial basin for ship repair or construction, opening into navigable water and provided with gates at its entrance to permit removal of water from within the dock after a ship has been floated into position. The docks are rectangular and, in cross-section, are somewhat U-shaped, with a floor and two side walls. At the inshore end the side walls may curve inward to receive the bow or stern of a vessel. In several modern docks the inshore portions have been made square ended. In older docks the side walls slope outward in steps called "altars," while in modern practice the side walls are either entirely vertical or slightly battered, with only one or two steps or "altars." The outer end is closed to the sea by a floating steel caisson gate. Many older docks made use of swinging steel miter gates, similar to those used in navigation locks.