Dry dock

A dry dock (sometimes dry-dock or drydock) 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.At the beginning of the dynasty (c. +965) the two Che provinces (now Chekiang and southern Chiangsu) presented (to the throne) two dragon ships each more than 200 ft. in length. The upper works included several decks with palatial cabins and saloons, containing thrones and couches all ready for imperial tours of inspection. After many years, their hulls decayed and needed repairs, but the work was impossible as long as they were afloat. So in the Hsi-Ning reign period (+1068 to +1077) a palace official Huang Huai-Hsin suggested a plan. A large basin was excavated at the north end of the Chin-ming Lake capable of containing the dragon ships, and in it heavy crosswise beams were laid down upon a foundation of pillars. Then (a breach was made) so that the basin quickly filled with water, after which the ships were towed in above the beams. Then (breach now being closed) the water was pumped out by wheels so that the ships rested quite in the air. When the repairs were complete, the water was let in again, so that the ships were afloat once more (and could leave the dock). Finally the beams and pillars were taken away, and the whole basin covered over with a great roof so as to form a hangar in which the ships could be protected from the elements and avoid the damage caused by undue exposure. (Wade-Giles spelling.)Reconstruction of the merchant ship Ceres in dry dock, Dieppe, France, ca 1854-1855The Royal Naval Dockyard, Bermuda as seen by Anna Brassey in 1883, with its floating drydock in the backgroundThe towboat Dolphin I in Bollinger Shipyards floating Drydock #2 on the Mississippi River in Algiers, New Orleans, LouisianaBlohm + Voss Dock 10, at the Port of HamburgFloating dry dock located in SevastopolA boat lift is a light duty form of dry dock which keeps small boats out of the water while not in useShip in the floating dry dock of Bremer Vulkan shipyard during an inspection of its propeller and rudderFloating dry dock Jong Shyn No. 8 in Kaohsiung Harbour A dry dock (sometimes dry-dock or drydock) 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. The use of dry docks in China goes at least as far back the 10th century A.D. In 1088, Song Dynasty scientist and statesman Shen Kuo (1031–1095) wrote in his Dream Pool Essays: The first English and oldest surviving dry dock still in use was commissioned by Henry VII of England at HMNB Portsmouth in 1495 (see Tudor navy). This dry dock currently holds the world's oldest commissioned warship, HMS Victory. Possibly the earliest description of a floating dock comes from a small Italian book printed in Venice in 1560, called Descrittione dell'artifitiosa machina. In the booklet, an unknown author asks for the privilege of using a new method for the salvaging of a grounded ship and then proceeds to describe and illustrate his approach. The included woodcut shows a ship flanked by two large floating trestles, forming a roof above the vessel. The ship is pulled in an upright position by a number of ropes attached to the superstructure. The Saint-Nazaire's Chantiers de l'Atlantique owns one of the biggest in the world: 1,200 by 60 metres (3,940 ft × 200 ft). The largest graving dock of the Mediterranean as of 2009 is at the Hellenic Shipyards S.A. (HSY S.A., Athens, Greece). The Alfredo da Silva Dry Dock in Almada, Portugal, was closed in 2000. The largest roofed dry dock is at the German Meyer Werft Shipyard in Papenburg, Germany, it is 504 m long, 125 m wide and stands 75 m tall. Harland and Wolff Heavy Industries in Belfast, Northern Ireland, is the site of a large dry dock 556 by 93 metres (1,824 ft × 305 ft). The massive cranes are named after the Biblical figures Samson and Goliath. Dry Dock 12 at Newport News Shipbuilding at 662 by 76 metres (2,172 ft × 249 ft) is the largest dry dock in the USA. The largest floating-dock in North America is named The Vigorous. It is operated by Vigor Industries in Portland, OR, in the Swan Island industrial area along the Willamette River. A graving dock is the traditional form of dry dock. It is narrow basin, usually made of earthen berms and concrete, and closed by gates or by a caisson. When open, a vessel is floated in and the water pumped out, leaving the craft supported on blocks.