A dry dock (sometimes drydock or 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.
The use of dry docks in China goes at least as far back as the 10th century A.D. [1] In 1088, Song dynasty scientist and statesman Shen Kuo (1031–1095) wrote in his Dream Pool Essays :
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. [2] [3]
The Greek author Athenaeus of Naucratis (V 204c-d) reports something that may have been a dry dock in Ptolemaic Egypt in the reign of Ptolemy IV Philopator (221-204 BC) on the occasion of the launch of the enormous Tessarakonteres rowing ship. [4] However a more recent survey by Goodchild and Forbes does not substantiate its existence. [5]
But after that a Phoenician devised a new method of launching it (the Tessarakonteres), having dug a trench under it, equal to the ship itself in length, which he dug close to the harbour. And in the trench he built props of solid stone five cubits deep, and across them he laid beams crosswise, running the laces whole width of the trench, at four cubits' distance from one another; and then making a channel from the sea he filled all the space which he had excavated with water, out of which he easily brought the ship by the aid of whatever men happened to be at hand; then closing the entrance which had been originally made, he drained the water off again by means of engines (organois); and when this had been done the vessel rested securely on the before-mentioned cross-beams. [6]
It has been calculated that a dock for a vessel of such a size might have had a volume of 750,000 gallons of water. [7]
Before the 15th century, when the hull below the waterline needed attention, careening was practised: at high tide the vessel was floated over a beach of hard sand and allowed to rest on one side when the tide receded. An account of 1434 described how a site near Southampton with a bottom of soft mud was selected for the warship Grace Dieu , so that the hull would bed itself in and remain upright at low tide. A timber, brushwood and clay wall was then built up around the hull. [8] The first early modern purpose-built European and oldest surviving dry dock still in use was commissioned by Henry VII of England at HMNB Portsmouth in 1495. [9] This was a timber-lined excavation, with the seaward end closed off by a temporary revetted bank of rock and clay that had to be dug away by hand (an operation taking typically 29 days, working night and day to accord with the tides [10] ) to allow the passage of a ship. [11] Emptying was by a pump, possibly in the form of a bucket-chain powered by horses. [12] This dry dock currently holds First World War monitor HMS M33.
Possibly the earliest description of a floating dock comes from a small Italian book printed in Venice in 1560, called Descrittione dell'artifitiosa machina. [13] 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 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. [14]
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 United States. 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. [15]
A graving dock is the traditional form of dry dock. [16] It is a narrow basin, usually made of earthen berms and concrete, closed by gates or a caisson. A vessel is floated in with the gates open, then the gates are closed and the water is 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 the vessel. 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 sonar domes protruding beneath the hull, requiring the hull to be supported several metres above the bottom of the dry dock, or depressions built into the floor of the dock, to accommodate the protrusions. [17]
Once the remainder of the water is pumped out, the ship can be freely inspected or serviced. When work on the ship is finished, the gates are opened to allow water in, and the ship is carefully refloated.
Modern graving docks are box-shaped, to accommodate newer, boxier ships, whereas old dry docks are often shaped like the ships expected to dock 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.[ citation needed ]
Dry docks used for building naval vessels may occasionally be built with a roof, to prevent spy satellites from taking pictures of the dry dock and any vessels that may be in it. During World War II, the German Kriegsmarine used fortified dry docks to protect its submarines from Allied air raids (see submarine pen).
An advantage of covered dry docks is that work can take place in any 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.
A 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 or converted out of an existing obsolete barge, potentially coming with their own bow and steering mechanism. [18]
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 drydocks extensively to provide maintenance in remote locations. Two examples of these were the 1,000-foot AFDB-1 and the 850-foot AFDB-3. The latter, 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. [19] [20]
A downside of floating dry docks is that unscheduled sinkings and off-design dives may take place, as with the Russian dock PD-50 in 2018. [21]
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.
The Great Balance Dock, built in New York City in 1854, was the largest floating drydock in the world when it was launched. It was 325 feet (99 m) long and could lift 8,000 tons, accommodating the largest ships of its day. [22]
Apart from graving docks and floating dry docks, ships can also be dry docked and launched by:
Some 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.
ABSD-7, an advanced base sectional dock, was constructed of seven advance base docks (ABD) as follows: ABD-37, ABD-38, ABD-39, and ABD-40 were built by Chicago Bridge & Iron Company, Morgan City, Louisiana, and completed in December 1944 and January and February 1945; ABD-51 and ABD-52 were built by Pollock-Stockton Shipbuilding Company, Stockton, California, and completed in January and March 1945; and ABD-58 was built by Pittsburgh-Des Moines Steel Co., Pittsburgh, Pennsylvania, and completed in October 1944.
A cofferdam is an enclosure built within a body of water to allow the enclosed area to be pumped out or drained. This pumping creates a dry working environment so that the work can be carried out safely. Cofferdams are commonly used for construction or repair of permanent dams, oil platforms, bridge piers, etc., built within water. They also form an integral part of naval architecture.
Seaspan ULC provides marine-related services to the Pacific Northwest. Within the Group are three (3) shipyards, an intermodal ferry and car float business, along with a tug and barge transportation company that serves both domestic and international markets. Seaspan, is part of the Washington Companies that are owned by Dennis Washington. Kyle Washington, is the Executive Chairman of Seaspan, who has become a Canadian citizen.
USS Artisan (ABSD-1), later redesignated as (AFDB-1), was a ten-section, non-self-propelled, large auxiliary floating drydock of the United States Navy. The only U.S. warship with this name, Artisan was constructed in sections during 1942 and 1943 by the Everett-Pacific Shipbuilding & Dry Dock Company, in Everett, Washington; the Chicago Bridge & Iron Company, in Eureka, California; the Pollock-Stockton Shipbuilding Company, in Stockton, California; and the Chicago Bridge & Iron Company, in Morgan City, Louisiana. This ship was commissioned at Everett, Washington, on 10 May 1943, Captain Andrew R. Mack in command. With all ten sections joined, she was 927 feet (283 m) long, 28 feet (8.5 m) tall, and with an inside clear width of 133 feet 7 inches (40.72 m).
The Rotterdamsche Droogdok Maatschappij NV (RDM) was a major shipbuilding and repair company in Rotterdam in the Netherlands, existing from 1902 to 1996. It built 355 ships, 18 of which were submarines. During its existence, the shipyard operated 12 floating docks and employed 7,000 people at its peak.
A caisson is a form of lock gate. It consists of a large floating iron or steel box. This can be flooded to seat the caisson in the opening of the dock to close it, or pumped dry to float it and allow it to be towed clear of the dock.
An auxiliary floating drydock is a type of US Navy auxiliary floating dry dock. Floating dry docks are able to submerge underwater and to be placed under a ship in need of repair below the water line. Water is then pumped out of the floating dry dock, raising the ship out of the water. The ship becomes blocked on the deck of the floating dry dock for repair. Most floating dry docks have no engine and are towed by tugboats to their destinations. Floating dry docks come in different sizes to accommodate varying ship sizes, while large floating dry docks come in sections and can be combined to increase their size and lift power. Ballast pontoon tanks are flooded with water to submerge or pumped dry to raise the ship.
YFD-2 was an auxiliary floating drydock built for the United States Navy in 1901. The first parts were laid down in early 1901 at Maryland Steel Co. of Sparrows Point, Maryland. YFD-2 was the first of its kind, steel movable auxiliary floating drydock, used to raise large ships out the water for repair below the ship's waterline. YFD-2 had a 18,000 tons lifting capacity.
USS AFDM-2,, is an AFDM-3-class medium auxiliary floating drydock built in Mobile, Alabama by the Alabama Drydock and Shipbuilding Company for the U.S. Navy. Originally named USS YFD-4, Yard Floating Dock-4, she operated by Todd Shipyards at New Orleans, Louisiana for the repair of US ships during World War II. YFD-4 was renamed an Auxiliary Floating Dock Medium AFDM-2 in 1945 after the war.
USS ABSD-2, later redesignated as AFDB-2, was a ten-section, non-self-propelled, large auxiliary floating drydock of the US Navy. Advance Base Sectional Dock-2 was constructed in sections during 1942 and 1943 by the Mare Island Naval Shipyard in Vallejo, California for World War II. Her official commissioning ceremony took place on 14 August 1943 with CDR Joseph J. Rochefort in command. With all ten sections joined, she was 927 feet (283 m) long, 28 feet (8.5 m) tall, and with an inside clear width of 133 feet 7 inches (40.72 m). ABSD-2 had a traveling 15-ton capacity crane with an 85-foot (26 m) radius and two or more support barges. The two side walls were folded down under tow to reduce wind resistance and lower the center of gravity. ABSD-2 had 6 capstans for pulling, each rated at 24,000 lbf (110,000 N) at 30 ft/min (0.15 m/s), 4 of the capstans were reversible. There were also 12 ballast compartments in each section.
ABSD-3 is an advanced base sectional dock, constructed of nine advance base dock (ABD) sections for the US Navy as an auxiliary floating drydock for World War II. ABSD-3 was delivered to the US Navy in April 1944, and was commissioned on 27 October 1944. Advance Base Sectional Dock-3 was constructed in sections during 1942 and 1943.
ABSD-6 is an advanced base sectional dock which was constructed of nine advance base docks (ABD) sections for the US Navy as an auxiliary floating drydock for World War II. ABSD-6 was built by Mare Island Naval Shipyard at Vallejo, California. ABSD-6 was commissioned on 28 September 1944. Advance Base Sectional Dock-6 was constructed in sections during 1942 and 1943. Each section are 3,850 tons and are 93 feet long each. Each Section had a 165 feet beam, a 75 feet molded depth and had 10,000 tons lifting capacity each. There were 4 ballast compartments in each section. With all nine sections joined, she was 825 feet long, 28 feet tall, and with an inside clear width of 133 feet 7 inches. ABSD-2 had a traveling 15-ton capacity crane with an 85-foot radius and two or more support barges. The two side walls were folded down under tow to reduce wind resistance and lower the center of gravity. ABSD-6 had 6 capstans for pulling, each rated at 24,000 lbf (110,000 N) at 30 ft/min (0.15 m/s), 4 of the capstans were reversible.
USS ABSD-4, later redesignated as AFDB-4, was a nine-section, non-self-propelled, large auxiliary floating drydock of the US Navy. Advance Base Sectional Dock-4 was constructed in sections during 1942 and 1943 by the Mare Island Naval Shipyard in Vallejo, California for World War II. With all ten sections joined, she was 927 feet long, 28 feet tall, and with an inside clear width of 133 feet 7 inches. ABSD-4 had a traveling 15-ton capacity crane with an 85-foot radius and two or more support barges. The two side walls were folded down under tow to reduce wind resistance and lower the center of gravity. ABSD-4 had 6 capstans for pulling, each rated at 24,000 lbf (110,000 N) at 30 ft/min (0.15 m/s), 4 of the capstans were reversible. There were also 4 ballast compartments in each section.
USS ABSD-5, later redesignated as AFDB-5, was a nine-section, non-self-propelled, large auxiliary floating drydock of the US Navy. Advance Base Sectional Dock-5 was constructed in sections during 1943 and 1944 by the Chicago Bridge & Iron Company in Morgan City, Louisiana for World War II. With all nine sections joined, she was 825 feet long, 28 feet tall, and with an inside clear width of 133 feet 7 inches. ABSD-5 had two traveling 15-ton capacity crane with an 85-foot radius and two or more support barges. The two side walls were folded down under tow to reduce wind resistance and lower the center of gravity. ABSD-5 had 6 capstans for pulling, each rated at 24,000 lbf (110,000 N) at 30 ft/min (0.15 m/s), 4 of the capstans were reversible. There were also 4 ballast compartments in each section.
USS ARD-1 was an auxiliary repair dock serving with the United States Navy during World War II as Auxiliary floating drydock. ARD-1 was built by the Pacific Bridge Company and completed in September 1934. ARD-1 was commissioned at Alameda, California on 19 December 1935 then towed to San Diego, California. ARD-1 was the first in her class of self-sustaining, ship hull shape ship repair docks. ARD-1 was able to repair ships in a Naval fleet in remote locations.
Everett-Pacific Shipbuilding & Dry Dock Company was established in 1942 to build ships needed for World War II. Yard construction began on 1 March 1942. As part of the Emergency Shipbuilding Program, the US Navy provided some of the capital to start Everett-Pacific Shipbuilding at Port Gardner Bay in Everett, Washington. Everett-Pacific was sold in 1945 to the Pacific Car and Foundry, who was already a major manufacturer of railcars and trucks. Pacific Car and Foundry was building barges for the US Navy during World War II at plants in Renton, Seattle and Tacoma in the state of Washington. The lease for the shipyard in Everett, Washington ended in 1949 and the yard closed. Pacific Car and Foundry in 1972 changed its name to Paccar Inc. to reflect its major products. The Everett-Pacific shipyard site later became part of Western Gear, a heavy machinery manufacturer. From 1987 to 1992, the shipyard was rebuilt to become part of Naval Station Everett. Everett-Pacific Shipbuilding was started by William Pigott Jr. a Seattle businessmen and his brother Paul Pigott (1900-1961). William Pigott Jr. was born in 26 Aug. 1895 in Pueblo, CO and died on 8 July 1947 in San Francisco, CA.
Pollock-Stockton Shipbuilding Company was established in 1942 to build ships needed for World War II. As part of the Emergency Shipbuilding Program the US Navy provided some of the capital to start Pollock-Stockton Shipbuilding at Stockton, California. The shipyard was located at San Joaquin River and Stockton Channel, near Louis Park. After the war the shipyard closed down in February 1946.
Onrust Dock of 3,000 tons, was a floating dry dock that served in the Dutch East Indies from 1869 till at least 1933. Up till about 1910 she was a crucial part of the Dutch naval infrastructure in the Indies.
Surabaya Wooden Dock of 1,100 tons was the first floating dry dock of the Dutch East Indies.
The Great Balance Dock was a floating drydock in New York City. It was the largest such facility in the world when constructed in 1854, and consequently, many of the most important ships of its time were serviced there.
Due to interruptions in the supply of electric power to the PD-50, the floating dock dived out in an off-design mode.
