Careening is a method of gaining access to the hull of a sailing vessel without the use of a dry dock. It is used for cleaning or repairing the hull. Before ship's hulls were protected from marine growth by fastening copper sheets over the surface of the hull, fouling by this growth would seriously affect the sailing qualities of a ship, causing a large amount of drag.
An Old Whaler Hove Down For Repairs, Near New Bedford, a wood engraving drawn by F. S. Cozzens and published in Harper's Weekly, December 1882
HMS Formidable careened in Malta Dockyard, 31 January 1843
A diagram of careening, from the Lärobok i sjömanskap (Textbook of Seamanship) by Wilhelm Linder, 1896
A dry dock is a narrow basin or vessel that can be flooded to allow a load to be floated in, then drained to allow that load to come to rest on a dry platform. Dry docks are used for the construction, maintenance, and repair of ships, boats, and other watercraft.
U.S. Navy submarine USS Greeneville in a graving dock
A US Navy littoral combat ship in drydock, NASSCO 2012
Floating Dock. Woodcut from Venice (1560)
The Stockholm brig "Tre Kronor" in one of the historical dry docks on the island Beckholmen in central Stockholm
