An auxiliary floating drydock is a type of US Navyfloatingdry 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. Ballastpontoontanks are flooded with water to submerge or pumped dry to raise the ship.
Auxiliary floating drydock YFD-2, built in 1901, was at Pearl Harbor. YFD-2 was repairing the US destroyer USS Shaw on 7 December 1941 during the attack on the harbor. Both YFD-2 and USS Shaw were repaired, after being hit and damaged in the attack.
The auxiliary floating drydock USS Dewey, built in 1905, was scuttled at Mariveles to prevent its capture by the Japanese. In 1942 Japan raised the Dewey, but it was resunk by US forces.
Auxiliary floating dry dock USS ARD-1, built in 1933, was also at Pearl Harbor. USS ARD-1 was a self-sustaining mobile dry dock.
To reduce travel time for repair work, over 150 auxiliary floating dry docks of different sizes were built during World War II between 1942 and 1945. These newly built floating dry docks had a lift capacity of 400 to 100,000 tons. Without these forward repair bases, ships would have had to return to the US for repairs. Between 1 October 1944 and 17 October 1945, 7,000 ships were repaired in auxiliary floating dry docks. After World War II some auxiliary floating dry docks were sold for private use and others were scrapped. In addition to auxiliary floating dry docks, timber floating dry docks were built for use in World War II. Timber floating dry docks had a lift capacity of 400 to 20,000 tons. They were not towed across the open ocean and were not given a US Navy class.
During wartime, ships in continuous use need repair both from wear and from war damage such as from naval mines, kamikaze attacks, dive bombs and torpedoes. Rudders and propellers are best serviced on dry docks. Without remote on-location dry docks, months could be lost if a ship returned to a home port for repair.
Most auxiliary floating drydocks had provisions for the repair crew, including bunk beds, meals, and laundry. Most had power stations, ballastpumps, repair shops, machine shops, and mess halls to be self-sustaining. Some auxiliary floating drydocks also had provisions for the ship under repair, but when possible, the crew of the damaged ship remained on ship while repairs were done. Many had cranes able to lift tons of material and parts to remove damaged parts and to install new parts.
Auxiliary Floating Docks, Big (AFDB), also known as Advance Base Sectional Docks (ABSD), came in sections, 93 ft long and 3,850 tons each. Each section had a 165-ft beam, a 75-ft molded depth, and 10,000 tons of lifting capacity. Sections could be put together to lift larger ships. AFDB were needed to repair battleships, aircraft carriers, cruisers, and large auxiliary ships. The AFDB-1 Artisan had 10 sections (A to J) for a total lift of 100,000 tons, and was 1,000 ft long with all 10 sections installed. AFDB-1 to 7 were built between 1943 and 1945 and towed to remote navy bases. An AFDB would have a crew of 600 to 1,000 men, a fresh-water distilling plant and was otherwise self-sustaining. They had a rail traveling 15-ton capacity crane with an 85-foot radius and two or more support barges. To pump water from the tanks, there were two 24-in discharge pumps on each section, each pump rated 15,000 gpm. For electricity, there were two 350-kw diesel AC generators on each section, producing 440 volts 3-phase 60-cycle power. AFDBs had steam plants to run the pumps. Each section could store 65,000 gallons of fuel oil to supply the ships under repair. Crew lived in barracks ships, called APL, that docked next to the AFDB.
AFDM are from 6,800 to 8,000 tons and are from 528 to 622 feet long. An AFDM has a crew of 140 to 200 men. An AFDM had a lift capacity 18,000 tons and was armed with two 40 mm and four 20 mm guns. It also had two 7+1⁄2-ton cranes with 16 ballast tank compartments. AFDMs were built in three pieces, a long center section and two shorter sections, one at each end. All AFDM also had Yard Floating Docks (YFD) class numbers.
Auxiliary repair dock Mobile (ARDM) are 5,200 tons and 489 feet long. ARDs had a ship form hull and lifting capacity of 3,500 tons. ARDMs were used to repair destroyers, submarines, and small auxiliaries. ARDMs had a crew of 130 to 160 men.
USS Dynamic (AFD-6) at Virginia Beach, Va. on Nov. 2, 2006
Auxiliary Floating Docks, Light (AFDL), also known as Auxiliary Floating Docks (AFD), were 288 ft long, had a beam of 64 ft (20 m), and draft of 3 ft 3 in (0.99 m) empty and 31 ft 4 in (9.55 m) flooded to load a ship. A normal crew was 60 men. AFDL displacement was 1,200 tons and could lift 1,900 tons. AFDL were built as one piece, open at both ends. AFDL were used to repair small craft, PT boats and small submarines. All AFD were reclassified AFDL after the war in 1946.
Auxiliary Repair Docks were built by Pacific Bridge Company in Alameda, California. ARD are 483 ft long, have a beam of 71 ft, a draft of 5 ft, and a displacement of 4,800 tons. The crew complement is 6 officers and 125 enlisted. ARD have an armament of two single Oerlikon 20 mm cannons, a bow and are sea worthy. They are self-sustaining with rudders to help in tow moving and have two cranes with a five-ton capacity. ARD also have a stowage barge for extra space. They were used to repair destroyers and submarines. Class 2 could repair Landing Ship, Tank (LST). The stern of the ship is open to allow a ship in need of repair to enter.
USS ARD-1 Displacement of 2,200 tons. Built in 1933. Only one in class.
Auxiliary Repair Dock, Concrete were mobile dry docks made of concrete, due to the shortage of steel during World War II. ARDC had a 2,800 ton lifting capacity. ARDC were 389 ft long, 84 ft wide, and 40 ft deep. ARDC has a crew of five officers and 84 enlisted men. Each had a 5-ton crane, with a 42 ft reach. Eight were built at Wilmington, North Carolina, and five at San Pedro in Los Angeles, California.
ARDC 1 – Changed to AFDL-34. Sold to Taiwan in 1959 Han Jih.
ARDC 2 – Changed to AFDL-35. Scrapped in 1974.
ARDC 3 – Changed to AFDL-36. Sold to Taiwan in 1947 Hay Tan. Scuttled in 2000.
ARDC 4 – Changed to AFDL-37. Scrapped in 1981.
ARDC 5 – Changed to AFDL-38. Placed out of service, date unknown. Final Disposition, transferred to San Francisco Maritime National Historical Park and leased to Bay Ship and Yacht shipyard at Alameda, CA.
ARDC 6 – Changed to AFDL-39. Sold to Brazil in 1980 Cidade de Natal.
ARDC 7 – Changed to AFDL-40. Sold to the Philippines in 1990.
ARDC 8 – Changed to AFDL-41. Sold in 1983 to North Florida Shipyard
ARDC 10 – Changed to AFDL-43. Scrapped in 1979.
ARDC 11 – Changed to AFDL-44. Sold to the Philippines in 1969.
ARDC 12 – Changed to AFDL-45. Sold to Todd Seattle 1945. Sold 1981 to Puglia Engineering.
ARDC-13 – Changed to AFDL-46. Destroyed at Bikini in 1946.
Yard Floating Dock (YFD)
YFD-2 The first Yard Floating Dock built in 1901, arriving Pearl Harbor 23 Oct. 1940 from New Orleans Naval Yard
Yard Floating Dock (YFD) was used for many types of floating docks, mostly used for harbor or shipyard use. YFDs normally had little-to-no crew space and were serviced from shore. Some auxiliary Repair Docks were converted to YFDs. Types of YFDs were: 400-ton concrete docks, 1,000-ton, 3,000-ton and 5,000-ton wood docks; sectional wood docks from 7,000 to 20,000 tons lifting capacity and a three-piece self docking steel sectional docks with 14,000 to 18,000 tons lifting capacity. All Medium Auxiliary Floating Dry Docks were converted to YFDs after World War II.
This article includes information collected from the Naval Vessel Register, which, as a U.S. government publication, is in the public domain. The entries can be found here and here. – sections a, g, h, i, j, and e