| 词条 | Dry dock | ||||||||
| 释义 |
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. HistoryMedieval ChinaThe use of dry docks in China goes at least as far back the 10th century A.D.[1] In 1088, Song Dynasty scientist and statesman Shen Kuo (1031–1095) wrote in his Dream Pool Essays: {{quote|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.)[2][3]}}Renaissance EuropeThe first English{{sfn|Sarton|1946|p=153}} 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.[4] 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. Modern eraThe Saint-Nazaire's Chantiers de l'Atlantique owns one of the biggest in the world: {{convert|1200|x|60|m}}. 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.[5] Harland and Wolff Heavy Industries in Belfast, Northern Ireland, is the site of a large dry dock {{convert|556|x|93|m}}. The massive cranes are named after the Biblical figures Samson and Goliath. Dry Dock 12 at Newport News Shipbuilding at {{convert|662|x|76|m}} 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.[6] TypesGraving{{unreferenced section|date=November 2012}}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. The keel blocks as well as the bilge block are placed on the floor of the dock in accordance with the "docking plan" of the ship. Routine use of dry docks is for the "graving" i.e. the cleaning, removal of barnacles and rust, and re-painting of ships' hulls. Some fine-tuning of the ship's position can be done by divers while there is still some water left to manoeuvre it about. It is extremely important that supporting blocks conform to the structural members so that the ship is not damaged when its weight is supported by the blocks. Some anti-submarine warfare warships have protruding sonar domes, requiring that the hull of the ship be supported several metres from the bottom of the drydock. Once the remainder of the water is pumped out, the ship can be freely inspected or serviced. When work on the ship is finished, water is allowed to re-enter the dry dock and the ship is carefully refloated. Modern graving docks are box-shaped, to accommodate the newer, boxier ship designs, whereas old dry docks are often shaped like the ships that are planned to be docked there. This shaping was advantageous because such a dock was easier to build, it was easier to side-support the ships, and less water had to be pumped away.{{cn|date=November 2018}} Dry docks used for building Navy vessels may occasionally be built with a roof. This is done to prevent spy satellites from taking pictures of the dry dock and any ships or submarines that may be in it. During World War II, fortified dry docks were used by the Germans to protect their submarines from Allied air raids (see submarine pen). Today, covered dry docks are usually used only when servicing or repairing a fleet ballistic missile submarine.{{cn|date=November 2018}} Another advantage of covered dry docks is that work can take place independently of the weather; this is frequently used by modern shipyards for construction especially of complex, high-value vessels like cruise ships where delays would incur a high cost. FloatingA floating dry dock is a type of pontoon for dry docking ships, possessing floodable buoyancy chambers and a "U"-shaped cross-section. The walls are used to give the dry dock stability when the floor or deck is below the surface of the water. When valves are opened, the chambers fill with water, causing the dry dock to float lower in the water. The deck becomes submerged and this allows a ship to be moved into position inside. When the water is pumped out of the chambers, the dry dock rises and the ship is lifted out of the water on the rising deck, allowing work to proceed on the ship's hull. A large floating dry dock involves multiple rectangular sections. These sections can be combined to handle ships of various lengths, and the sections themselves can come in different dimensions. Each section contains its own equipment for emptying the ballast and to provide the required services, and the addition of a bow section can facilitate the towing of the dry dock once assembled. For smaller boats, one-piece floating dry docks can be constructed, potentially coming with their own bow and steering mechanism.[7] Shipyards operate floating dry docks as one method for hauling or docking vessels. Floating drydocks are important in locations where porous ground prevents the use of conventional drydocks, such as at the Royal Naval Dockyard on the limestone archipelago of Bermuda. Another advantage of floating dry docks is that they can be moved to wherever they are needed and can also be sold second-hand. During World War II, the U.S. Navy used such Auxiliary floating drydock extensively to provide maintenance in remote locations. Two of these are the 1,000 feet AFDB-1 and the 850-foot AFDB-3, an Advance Base Sectional Dock, which saw action in Guam, was mothballed near Norfolk, Virginia, and was eventually towed to Portland, Maine, to become part of Bath Iron Works' repair facilities.[8][9] A downside of floating dry docks is that unscheduled sinkings and off-design dives may take place.[10] The "Hughes Mining Barge", or HMB-1, is a covered, floating drydock that is also submersible to support the secret transfer of a mechanical lifting device underneath the Glomar Explorer ship, as well as the development of the Sea Shadow stealth ship. GalleryAlternative dry dock systemsApart from graving docks and floating dry docks, ships can also be dry docked and launched by:
Other usesSome dry docks are used during the construction of bridges, dams, and other large objects. For example, the dry dock on the artificial island of Neeltje-Jans was used for the construction of the Oosterscheldekering, a large dam in the Netherlands that consists of 65 concrete pillars weighing 18,000 tonnes each. The pillars were constructed in a drydock and towed to their final place on the seabed. A dry dock may also be used for the prefabrication of the elements of an immersed tube tunnel, before they are floated into position, as was done with Boston's Silver Line. See also
References1. ^{{cite book|author=Levathes, Louise|title=When China Ruled the Seas|publisher=Oxford University Press|year=1994|isbn=978-0-19-511207-8|page=77}} 2. ^Needham, Joseph (1986). Science and Civilization in China: Volume 4 Part 3. Taipei: Caves Books, Ltd. Page 660 3. ^{{Cite book |title=China's Management Revolution: Spirit, Land, Energy |last= Bouée |first=Charles-Edouard |publisher=Palgrave Macmillan |year=2010 |isbn=978-0230285453 |pages=84}} 4. ^{{harvnb|Sarton|1946|pp=153f.}} 5. ^{{cite web|title=Meyer Werft baut größte Dockhalle der Welt|url=http://www.spiegel.de/wirtschaft/0,1518,529589,00.html|date=2008-01-18|work= |publisher=Spiegelonline|accessdate=2009-06-25}} 6. ^{{Cite news|url=http://www.oregonlive.com/business/index.ssf/2014/11/north_americas_largest_drydock_1.html|title=North America's largest drydock floats first ship at Swan Island's Vigor Industrial (infographic and time lapse)|newspaper=OregonLive.com|access-date=2016-11-03}} 7. ^{{cite book | last = Noel | first = John V. | year = 1988 | title = Knight's Modern Seamanship | publisher = John Wiley and Sons | edition = 18 | isbn = 0-471-28948-5 | pages = 81–82 }} 8. ^Photos of USS Samuel B. Roberts on blocks in AFDB-3 in 1988 9. ^[https://books.google.com/books?id=bCEDAAAAMBAJ&pg=PA121&dq=popular+science+July+1946&hl=en&ei=hc3oTO6dCYvonQfQu5iaDQ&sa=X&oi=book_result&ct=book-thumbnail&resnum=10&ved=0CE4Q6wEwCTgU#v=onepage&q&f=true "Sea Going Navy Yard Follows The Fleet", November 1945, Popular Science] 10. ^{{cite news |last1=SEAN GALLAGHER |title=Russia’s only aircraft carrier damaged as its floating dry dock sinks |url=https://arstechnica.com/tech-policy/2018/10/russias-only-aircraft-carrier-damaged-as-its-floating-dry-dock-sinks/ |accessdate=5 November 2018 |work=Ars Technica |date=20 October 2018 |quote="Due to interruptions in the supply of electric power to the PD-50, the floating dock dived out in an off-design mode."}} Sources
| last = Sarton | first = George | title = Floating Docks in the Sixteenth Century | journal = Isis | volume = 36 | issue = 3/4 | pages = 153–154 | year = 1946 | doi=10.1086/347934 }} External links{{Commons category|Dry docks}}
4 : Drydocks|Chinese inventions|Coastal construction|English inventions |
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