Dry Dock
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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.


History


Greco-Roman world

The Greek author
Athenaeus of Naucratis Athenaeus of Naucratis (; grc, Ἀθήναιος ὁ Nαυκρατίτης or Nαυκράτιος, ''Athēnaios Naukratitēs'' or ''Naukratios''; la, Athenaeus Naucratita) was a Greek rhetorician and grammarian, flourishing about the end of th ...
(V 204c-d) reports something that may have been a dry dock in Ptolemaic Egypt in the reign of
Ptolemy IV Philopator egy, Iwaennetjerwymenkhwy Setepptah Userkare Sekhemankhamun Clayton (2006) p. 208. , predecessor = Ptolemy III , successor = Ptolemy V , horus = ''ḥnw-ḳni sḫꜤi.n-sw-it.f'Khunuqeni sekhaensuitef'' The strong youth whose f ...
(221-204 BC) on the occasion of the launch of the enormous ''
Tessarakonteres ''Tessarakonteres'' ( el, τεσσαρακοντήρης, "forty-rowed"), or simply "forty" was a very large catamaran galley reportedly built in the Hellenistic period by Ptolemy IV Philopator of Egypt. It was described by a number of ancient ...
'' rowing ship. It has been calculated that a dock for a vessel of such a size might have had a volume of 750,000
gallon The gallon is a unit of volume in imperial units and United States customary units. Three different versions are in current use: *the imperial gallon (imp gal), defined as , which is or was used in the United Kingdom, Ireland, Canada, Austr ...
s of water. In Roman times, a shipyard at Narni, which is still studied, may have served as a dry dock.


Medieval China

The use of dry docks in
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
goes at least as far back the 10th century A.D. In 1088,
Song Dynasty The Song dynasty (; ; 960–1279) was an imperial dynasty of China that began in 960 and lasted until 1279. The dynasty was founded by Emperor Taizu of Song following his usurpation of the throne of the Later Zhou. The Song conquered the rest ...
scientist and statesman Shen Kuo (1031–1095) wrote in his '' Dream Pool Essays'':


Renaissance Europe

The first early modern European and oldest surviving dry dock still in use was commissioned by
Henry VII of England Henry VII (28 January 1457 – 21 April 1509) was King of England and Lord of Ireland from his seizure of the crown on 22 August 1485 until his death in 1509. He was the first monarch of the House of Tudor. Henry's mother, Margaret Beauf ...
at HMNB Portsmouth in 1495 (see
Tudor navy The Tudor navy was the navy of the Kingdom of England under the ruling Tudor dynasty (1485–1603). The period involved important and critical changes that led to the establishment of a permanent navy and laid the foundations for the future Ro ...
). This dry dock currently holds First World War monitor
HMS M33 HMS ''M33'' is an of the Royal Navy built in 1915. She saw active service in the Mediterranean during the First World War and in Russia during the Allied Intervention in 1919. She was used subsequently as a mine-laying training ship, fuelling ...
. 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.


Modern era

The
Saint-Nazaire Saint-Nazaire (; ; Gallo: ''Saint-Nazère/Saint-Nazaer'') is a commune in the Loire-Atlantique department in western France, in traditional Brittany. The town has a major harbour on the right bank of the Loire estuary, near the Atlantic Ocean ...
's Chantiers de l'Atlantique owns one of the biggest in the world: . The Alfredo da Silva Dry Dock in
Almada Almada () is a city and a municipality in Portugal, located on the southern margin of the Tagus River, on the opposite side of the river from Lisbon. The two cities are connected by the 25 de Abril Bridge. The population in 2011 was 174,030, in a ...
,
Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...
, was closed in 2000. The largest roofed dry dock is at the German
Meyer Werft Meyer Werft is one of the major German shipyards, headquartered in Papenburg at the river Ems. Founded in 1795 and starting with small wooden vessels, today Meyer Werft is a builder of luxury passenger ships. 700 ships of different types have be ...
Shipyard in Papenburg,
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
, it is 504 m long, 125 m wide and stands 75 m tall.
Harland and Wolff Harland & Wolff is a British shipbuilding company based in Belfast, Northern Ireland. It specialises in ship repair, shipbuilding and offshore construction. Harland & Wolff is famous for having built the majority of the ocean liners for the W ...
Heavy Industries in
Belfast Belfast ( , ; from ga, Béal Feirste , meaning 'mouth of the sand-bank ford') is the capital and largest city of Northern Ireland, standing on the banks of the River Lagan on the east coast. It is the 12th-largest city in the United Kingdo ...
,
Northern Ireland Northern Ireland ( ga, Tuaisceart Éireann ; sco, label= Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is variously described as a country, province or region. Nort ...
, is the site of a large dry dock . The massive cranes are named after the Biblical figures
Samson Samson (; , '' he, Šīmšōn, label= none'', "man of the sun") was the last of the judges of the ancient Israelites mentioned in the Book of Judges (chapters 13 to 16) and one of the last leaders who "judged" Israel before the institution o ...
and Goliath. Dry Dock 12 at Newport News Shipbuilding at 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.


Types


Graving

A graving dock is the traditional form of dry dock. It is a narrow basin, usually made of earthen berms and concrete, closed by gates or by 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 Diver or divers may refer to: *Diving (sport), the sport of performing acrobatics while jumping or falling into water *Practitioner of underwater diving, including: **scuba diving, **freediving, **surface-supplied diving, **saturation diving, a ...
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 Anti-submarine warfare (ASW, or in older form A/S) is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are t ...
warships have
sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on o ...
domes protruding beneath the hull, requiring the hull to be supported several metres above 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, 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 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. Dry docks used for building Navy vessels may occasionally be built with a roof, to prevent
spy satellite A reconnaissance satellite or intelligence satellite (commonly, although unofficially, referred to as a spy satellite) is an Earth observation satellite or communications satellite deployed for military or intelligence applications. The ...
s from taking pictures of the dry dock and any vessels that may be in it. During World War II, fortified dry docks were used by the Germans to protect their
submarine A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...
s from Allied air raids (see
submarine pen A submarine pen (''U-Boot-Bunker'' in German) is a type of submarine base that acts as a bunker to protect submarines from air attack. The term is generally applied to submarine bases constructed during World War II, particularly in Germany and ...
). 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.


Floating

A floating dry dock is a type of pontoon for dry docking ships, possessing floodable
buoyancy Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the ...
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
valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings ...
s 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 Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship ...
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. 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 Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
archipelago of
Bermuda ) , anthem = "God Save the King" , song_type = National song , song = " Hail to Bermuda" , image_map = , map_caption = , image_map2 = , mapsize2 = , map_caption2 = , subdivision_type = Sovereign state , subdivision_name = , e ...
. 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 World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...
, the U.S. Navy used such
auxiliary floating drydock An auxiliary floating drydock is a type of US Navy 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, ...
s 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 Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
, was mothballed near
Norfolk Norfolk () is a ceremonial and non-metropolitan county in East Anglia in England. It borders Lincolnshire to the north-west, Cambridgeshire to the west and south-west, and Suffolk to the south. Its northern and eastern boundaries are the No ...
,
Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...
, and was eventually towed to
Portland Portland most commonly refers to: * Portland, Oregon, the largest city in the state of Oregon, in the Pacific Northwest region of the United States * Portland, Maine, the largest city in the state of Maine, in the New England region of the northeas ...
,
Maine Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and north ...
, to become part of
Bath Iron Works Bath Iron Works (BIW) is a major United States shipyard located on the Kennebec River in Bath, Maine, founded in 1884 as Bath Iron Works, Limited. Since 1995, Bath Iron Works has been a subsidiary of General Dynamics. It is the fifth-largest de ...
' repair facilities. A downside of floating dry docks is that unscheduled sinkings and off-design dives may take place, as with the Russian dock ''
PD-50 ''PD-50'' (russian: ПД-50), Soviet designation Project 7454, was a Russian large floating dry dock built at the Götaverken Arendal shipyard in Gothenburg, Sweden and commissioned in the 1980s. At the time, it was the world's largest floating ...
'' in 2018. The "
Hughes Mining Barge The ''Hughes Mining Barge'', or ''HMB-1'', is a submersible barge about 99 m (324 ft) long, 32 m (106 ft) wide, and more than 27 m (90 ft) tall. The ''HMB-1'' was originally developed as part of Project Azorian (mor ...
", 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 ''GSF Explorer'', formerly USNS ''Hughes Glomar Explorer'' (T-AG-193), was a deep-sea drillship platform built for Project Azorian, the secret 1974 effort by the United States Central Intelligence Agency's Special Activities Division to recove ...
'' ship, as well as the development of the ''
Sea Shadow ''Sea Shadow'' (IX-529) was an experimental stealth ship built by Lockheed for the United States Navy to determine how a low radar profile might be achieved and to test high stability hull configurations that have been used in oceanographic s ...
'' stealth ship. The
Great Balance Dock 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. Construction and Char ...
, built in
New York City New York, often called New York City or NYC, is the List of United States cities by population, most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the L ...
in 1854, was the largest floating drydock in the world when it was launched. It was long and could lift 8,000 tons, accommodating the largest ships of its day.


Alternative dry dock systems

Apart from graving docks and floating dry docks, ships can also be dry docked and launched by: *
Marine railway The patent slip or marine railway is an inclined plane extending from shoreline into water, featuring a "cradle" onto which a ship is first floated, and a mechanism to haul the ship, attached to the cradle, out of the water onto a slip. The ...
— For repair of larger ships up to about 3000 tons ship weight *
Shiplift A shiplift is a modern alternative for a slipway, a dry dock, floating dry dock or a dry dock, graving dry dock. A shiplift is used to dry dock and launch ships. It consists of a structural platform that is lifted and lowered exactly vertically, ...
— For repair as well as for new-building. From 800 to 25000 ton ship-weight *
Slipway A slipway, also known as boat ramp or launch or boat deployer, is a ramp on the shore by which ships or boats can be moved to and from the water. They are used for building and repairing ships and boats, and for launching and retrieving small ...
,
patent slip The patent slip or marine railway is an inclined plane extending from shoreline into water, featuring a "cradle" onto which a ship is first floated, and a mechanism to haul the ship, attached to the cradle, out of the water onto a slip. The m ...
— For repair of smaller boats and the new-building launch of larger vessels


Other uses

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 Neeltje Jans () is an artificial island in the Netherlands in the province of Zeeland, halfway between Noord-Beveland and Schouwen-Duiveland in the Oosterschelde. It was constructed to facilitate the construction of the Oosterscheldedam. After th ...
was used for the construction of the
Oosterscheldekering The Oosterscheldekering ( English: Eastern Scheldt storm surge barrier), between the islands Schouwen-Duiveland and Noord-Beveland, is the largest of the Delta Works, a series of dams and storm surge barriers, designed to protect the Netherlands ...
, a large dam in the
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
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 An immersed tube (or immersed tunnel) is a kind of undersea tunnel composed of segments, constructed elsewhere and floated to the tunnel site to be sunk into place and then linked together. They are commonly used for road and rail crossings of ...
tunnel, before they are floated into position, as was done with Boston's Silver Line.


Gallery

File:HM Dockyard Bermuda-Ana Brassey 1883.jpg, The
Royal Naval Dockyard, Bermuda HMD Bermuda ( Her/His Majesty's Dockyard, Bermuda) was the principal base of the Royal Navy in the Western Atlantic between American independence and the Cold War. The Imperial fortress colony of Bermuda had occupied a useful position astride ...
as seen by Anna Brassey in 1883, with its
floating drydock 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, ...
in the background File:Dry Dock, Toledo Ship Building Company, Toledo, Ohio - DPLA - 026258a24e87b8b896620a2c045bd8a5 (page 1) (cropped).jpg, alt=Dry Dock, Toledo Ship Building Company, Toledo, Ohio, 1912, Dry Dock, Toledo Ship Building Company, Toledo, Ohio, 1912 File:DALPHIN I.jpg, Towboat ''Dolphin I'' in Bollinger Shipyards floating Drydock #2 on the
Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it f ...
in
Algiers, New Orleans Algiers is a historic neighborhood of New Orleans and is the only Orleans Parish community located on the West Bank of the Mississippi River. Algiers is known as the 15th Ward, one of the 17 Wards of New Orleans. It was once home to many jazz m ...
,
Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...
File:Blohm+Voss Dock10 Hafen Hamburg 2.jpg, Blohm + Voss Dock 10, at the Port of Hamburg Germany File:Sevastopol Floating dock 2008 G1.jpg, Floating dry dock located in
Sevastopol Sevastopol (; uk, Севасто́поль, Sevastópolʹ, ; gkm, Σεβαστούπολις, Sevastoúpolis, ; crh, Акъя́р, Aqyár, ), sometimes written Sebastopol, is the largest city in Crimea, and a major port on the Black Sea ...
File:Floating drydock fo a small boat.jpg, A boat lift is a light duty form of dry dock which keeps small boats out of the water while not in use File:Schiff im Dock, Malerarbeiten am Heck.png, Ship in the floating dry dock of Bremer Vulkan shipyard during an inspection of its propeller and rudder File:Kaohsiung Taiwan Floating-dock-Jong-Shyn-01.jpg, Floating dry dock Jong Shyn No. 8 in Kaohsiung Harbour, Taiwan File:2019-03-19 SOCIBER VALPARAISO III floating drydock.jpg, SOCIBER floating drydock, ''Valparaiso III'' with tugboat ''Pequen'', being worked on in the cradle, in Valparaiso, Chile File:Great Balance Dock with Adriatic.jpg, The Great Balance Dock with the steamer ''Adriatic'' aboard, c. 1860


See also

* * * * — 1942 attack on a dry dock during
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
.


References


Sources

* * *


External links


Encyclopædia Britannica, dry-dockCarnival Liberty Cruise Ship in Dry Dock in Freeport, Grand Bahamas"Docks's Life".
All about floating docks of shipbuilding firm "Almaz". St.-Petersburg. Russia. {{Authority control Coastal construction