Auxiliary floating drydock

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USS Artisan (ABSD-1) with USS Antelope (IX-109) and LST-120 in the dock at Espiritu Santo, New Hebrides Islands, 8 January 1945
Los Alamos (AFDB-7), with a repaired submarine at Holy Loch, Scotland in 1985

Auxiliary floating drydock are US Navy floating dry docks that are able to submerge under water and be placed under a ship in need of repair below the water line. Floating drydocks then rise up under the ship raising the ship out of the water. The ship is now blocked on the deck of the floating dry dock for repair. Most floating drydocks had no engine and are towed by tugboats to locations. Floating dry docks come in a different sizes to accommodate varying ship sizes. The large floating drydocks come in sections and can be assembled together to increase the size and lift power. Ballast pontoons tanks are flooded with water to submerge or pumped dry to raise the ship.[1][2]

World War 2[edit]

When World War 2 started the US Navy had only three steel auxiliary floating dry docks:

  1. Auxiliary floating drydock YFD-2 was at Pearl Harbor. YFD-2 was repairing the US destroyer USS Shaw on 7 December 1941 during the attack on the harbor. YFD-2 and USS Shaw were hit and damaged in the attack, both were repaired. [3]
  2. The auxiliary floating drydock USS Dewey that was scuttled at Mariveles to prevent its capture by the Japanese. In 1942 Japan raised the Dewey, but it was resunk by U.S. forces.
  3. Auxiliary floating dry dock ARD-1, (1933) was also at Pearl Harbor. ARD-1 was a self-sustaining dry dock.

To reduce travel time for repair work over 150 auxiliary floating dry dock of different sizes were built during World War 2, between 1942 and 1945. Without these forward repair bases, ships would have to return to the states for repair. After World War 2 some of the auxiliary floating dry docks were sold for private use and a few were scrapped.[4][2]


Ships in continuous use during war need repair both from wear and from war damage from naval mine, kamikaze, drive bombs and torpedoes. Rudders and propellers are best serviced on dry docks. Without remote on location dry docks, months could be lost in a ship returning to a home port for repair. Most auxiliary floating drydock had provisions for the repair crew, such bunk beds, meals, and laundry. Most had power stations, ballast pumps, repair shops, machine shops, and mess halls to be self-sustaining. Some of the auxiliary floating drydocks also had provisions for the ship under repair, but when possible, the crew of the damaged ship remained on their ship while repair was being made. Many had cranes able to lift tons of material and parts for removing damage parts and install new parts.[5] [2]


Most auxiliary floating drydock only has anti-aircraft guns for defense, as space would not allow for large guns. Typical armament were 40 mm and 20 mm machine guns. Japanese pilots sometime mistook empty auxiliary floating drydocks for a type of aircraft carrier. [6][2]

Large Auxiliary Floating Dry Docks (AFDB)[edit]

USS AFDB-3 with rail traveling 15-ton crane

Auxiliary Floating Docks, Big, came in sections that 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. They are also known as Advance Base Sectional Docks (ABSD). Sections could be put together to lift larger ships. AFDB were needed to repair battleships, aircraft carriers, cruisers, and large auxiliary ships. AFDB-1 Artisan had 10 sections (A to J) for a total lift of 100,000 tons and was 1,000 feet long with all 10 sections installed. AFDB-1 to 7 were built between 1943 and 1945 and then towed to remote navy bases. An AFDB would have a crew of 600 to 1000 men, have a fresh-water distilling plant and be self-sustaining. They had a rail traveling 15-ton capacity crane with a 85-foot radius and two or more support barges. To pump out the water in the tanks there were two 24-inch discharge pumps on each section, each pump rated 15,000 gpm. For power there were two 350-kw diesel AC generators on each section, producing 440 volts 3-phase 60-cycle power. Each section could store 65,000 gal. of fuel oil, this was to supply the ships under repair. [4][7][2][8]

Medium Auxiliary Floating Dry Docks (ADFM)[edit]

ADFM are from 6,800 to 8,000 tons and are from 528 to 622 feet long. ADFM has crew of 140 to 200 men. ADFM had a lift capacity 18,000 tons and armed with two 40mm and four 20mm guns. Had two 7 1/2 tons cranes with 16 ballast tank compartments.[4][16][2][17] All ADFM were converted to Yard Floating Docks (YFD) after the war.

  • USS AFDM-1 Chicago Bridge, YFD 3, scrapped 1986[18]
  • USS AFDM-2 Alabama DD, YFD 4, sold to private in 1999[19]
  • USS AFDM-3 Chicago Bridge, YFD 6, sold to private[20]
  • USS AFDM-4 Chicago Bridge, YFD 10 sold private in 1948
  • USS Resourceful (AFDM-5) Everett-Pacific, YFD 21, sold private in 1999[21]
  • USS Competent (AFDM-6) Everett-Pacific, YFD 62, sold private in 1997[22][23]
  • USS Sustain (AFDM-7) Everett-Pacific, YFD 63, leased to BAE Jacksonville in 1997[24]
  • USS Richland (AFDM-8) Chicago Bridge, YFD 64, scrapped in 2016[25]
  • USS AFDM-9 Chicago Bridge, YFD 65, sold private in 1989
  • USS Resolute (AFDM-10) Chicago Bridge, YFD 66, destroyed 1947[26]
  • USS AFDM-11 Chicago Bridge, YFD 67, sold private in 2004
  • USS AFDM-12 Kaiser Shipyards in Vancouver, Washington, YFD 68, scrapped in 1990
  • USS AFDM-13 Columbia Const. in Vancouver WA, YFD 69, sold private in 1969
  • USS Steadfast (AFDM-14) [1] Pollock-Stockton in Stockton, California, YFD 70, sold private in 1998[27]

Medium Auxiliary Repair Docks (ARDM)[edit]

Auxiliary repair dock Mobile (ARDM) are 5,200 tons and are 489 feet long. ARD had a ship form hull and lifting capacity of 3,500 tons. ARDM were used to repair destroyers, submarines, and small auxiliaries. ARDM has a crew of 130 to 160 men. [4][2]

Small Auxiliary Floating Dry Docks (AFDL)[edit]

Auxiliary Floating Docks, Light (AFDL). Also called Auxiliary Floating Docks (AFD) AFDL were 288 ft long, had a beam of 64 ft (20 m), and draft of 3 ft 3 in empty and 31 ft 4 in (9.55 m) flooded to load a ship. A normal crew was 60 men. AFDL displacement 1,200 tons and could lift 1,900 tons. AFDL has a crew of 30 to 130 men, living in a barge alongside the AFDL. Used to repair small crafts, PT boats and small submarines.[4][28][29]

  • USS Endeavor AFD-1 By Chicago Bridge
  • USS AFD-2 By Chicago Bridge [30]
  • USS AFD-3 By Chicago Bridge
  • USS AFD-4 By Chicago Bridge
  • USS AFD-5 By Chicago Bridge
  • USS Dynamic (AFD-6) By Chicago Bridge
  • USS Ability (AFD-7) By Chicago Bridge
  • USS AFD-8 By Chicago Bridge
  • USS AFD-9 By Chicago Bridge
  • USS AFD-10 By Chicago Bridge
  • USS AFD-11 By Chicago Bridge
  • USS AFD-12 [31]
  • USS AFD-13 Typhoon Ida sank off Okinawa, Japan on 16 September 1945.[32]
  • USS AFD-14
  • USS AFD-15
  • USS AFD-16
  • USS AFD-17
  • USS AFD-18
  • USS AFD-19 By George D. Auchter in Jacksonville, Florida
  • USS AFD-20 By George D. Auchter
  • USS AFD-21 By George D. Auchter [33]
  • USS AFD-22 By George D. Auchter [34]
  • USS Adept (AFD-23) By George D. Auchter
  • USS AFD-24 By Doullot & Ewin in Mobile, Alabama
  • USS AFD-25 By Doullot & Ewin
  • USS AFD-26 By Doullot & Ewin
  • USS AFD-27 By Doullot & Ewin
  • USS AFD-28 By Doullot & Ewin[35]
  • USS AFD-29 By Doullot & Ewin
  • USS AFD-30 By Foundation Co.[36]
  • USS AFD-31 By Foundation Co.
  • USS AFD-32 By Foundation Co.
  • USS AFD-33 By Foundation Co.

Auxiliary Repair Docks (ARD)[edit]

ARD-6 submerged at Dutch Harbor Alaska with Sub USS S-46 for repair 1944

Built by Pacific Bridge in Alameda CA and are 483 feet long, beam of 71 Feet, and draft of 5 Feet. Ship displacement 4,800 tons. Crew complement 6 Officers and 125 Enlisted. Armament of Two single Oerlikon 20 mm cannon. ARD had a crew of 100 to 160 men. ARD have a bow and are sea worthy. They are self-sustaining with a rudders to help in tow moving and have two cranes with a 5-ton capacity. Normal also had stowage barge for extra space. Used to repair destroyers and submarines. Class 2 could repair Landing Ship, Tank ((LST)). [4][2][37]

Auxiliary Repair Dock, Concrete (ARDC)[edit]

ARDC-13, An Auxiliary Repair Dock, Concrete
Auxiliary Repair Dock, Concrete under tow

Auxiliary Repair Dock, Concrete were mobile drydock made of concrete, due the shortage of steel during the war. ARDC had a 2,800 tons lifting capacity. ARDC were 389 feet long, 84 feet wide, and 40 feet deep. ARDC has a crew of five officers and 84 enlisted men. Each had a 5 ton crane, with a 42 feet reach. Eight were built at Wilmington, North Carolina and five at San Pedro in Los Angeles, California.[38][39][40][2]

  • 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 1981
  • ARDC 5 - Changed to AFDL-38 sold 1944 and 1981
  • ARDC 6 - Changed to AFDL-39 sold to Brazil 1980 Cidade de Natal
  • ARDC 7 - Changed to AFDL-40 sold to the Philippines 1990
  • ARDC 8 - Changed to AFDL-41 old 1983 to North Florida Shipyard[41]
  • ARDC 9 - Changed to AFDL-42 sold to Hurley Marine 1945, scrapped in 1975
  • ARDC 10 - Changed to AFDL-43 scrapped 1979 [42]
  • ARDC 11 - Changed to AFDL-44 sold the Philippines 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 [43]

Yard Floating Dock (YFD)[edit]

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 a many types of floating docks. These were mostly used for harbor or shipyard use. YFD normally had no or little crew space and were serviced from shore. Some auxiliary Repair Dock were converted to YFD. Types of YFD 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 YFD after the war.[44][45][2]

Image gallery[edit]

See also[edit]


  1. ^ The Pacific War Online Encyclopedia, Floating Dry Docks
  2. ^ a b c d e f g h i j Building the Navy's Bases in World War II, History of the Bureau of Yards and Docks and the Civil Engineer Corps 1940-1946 Chapter IX, Floating Drydocks
  3. ^ navsource, YFD-2
  4. ^ a b c d e f "Floating Dry-Docks (AFDB, AFDM, AFDL, ARD, ARDM, YFD)". 30 April 2015. Retrieved 8 January 2019.
  5. ^ USS ABSD-1 [1943-1946]
  6. ^ "Sea Going Navy Yard Follows The Fleet", November 1945, Popular Science
  7. ^ navsource, Artisan (AFDB-1)
  8. ^, ABSD-1 Floating Dry Dock on Espiritu Santo, A glimpse of WWII history
  9. ^ pacificwrecks, USS AFDB-2
  10. ^ navsource, USS AFDB-3
  11. ^ Photos of USS Samuel B. Roberts on blocks in AFDB-3 in 1988
  12. ^ Pacific Wrecks - AFDB-4 / ABSD-4 Auxiliary Floating Dry Dock 4
  13. ^ navsource, navsource, ABSD-4
  14. ^ USS AFDB-5
  15. ^ navsource, USS AFDB-6
  16. ^ navsource, AFDM Medium Auxiliary Floating Dry Dock
  17. ^ [ navsource, Medium Auxiliary Floating Dry Docks (ADFM)
  18. ^ USN Floating Dry Dock AFDM-1 in the Miraflores Locks, August 11, 2013
  19. ^ navsource, AFDM-1
  20. ^ navsource, USS AFDM-3
  21. ^ navsource, USS Resourceful (AFDM-5)
  22. ^ Global security AFDB Auxiliary Floating Dry Dock, Large
  23. ^ navsource, USS Competent (AFDM-6)
  24. ^ navsource, USS Sustain (AFDM-7)
  25. ^ navsource, USS Richland (AFDM-8)
  26. ^ navsource, USS AFDM-9
  27. ^ navsource, USS Steadfast (AFDM-14)
  28. ^, USS Ability (AFDL-7)
  30. ^ navsource, USS AFD-2
  31. ^ USS AFD-12
  32. ^ "Casualties, Navy & Coast Guard ships WWII". Archived from the original on 10 April 2014. Retrieved 9 March 2014.
  33. ^ navsource, USS AFD-21
  34. ^ navsource, USS AFD-22
  35. ^ navsource, USS AFD-28
  36. ^ navsource, USS AFD-30
  38. ^ "Final Report for Tests Able and Baker". Joint Task Force One. Bureau of Yards and Docks Group. 1946.
  39. ^ Dictionary of American Naval Fighting Ships: V. 6: R Through S, Appendices, By James L. Mooney.
  40. ^ Global security, Auxiliary Classes
  41. ^ navsource, ARDC 8
  42. ^ navsource, ARDC 10
  43. ^ navsource, ARDC-13
  44. ^ navsource, Yard Floating Dock (YFD)
  45. ^ The Navy of the Nuclear Age, 1947–2007, By Paul Silverstone
  46. ^ navsource, YFD-2
  47. ^ US Navy, YFD-2
  48. ^ National Park Service, Civilian Casualties,YFD-2
  49. ^ US Navy, Floating Drydock Resolute Ends 58 Years of Service to Navy, Story Number: NNS031107-31Release Date: 11/7/2003 11:40:00 PM, By Chief Journalist (SW/AW) Mark O. Piggott, Commander, Submarine Force, U.S. Atlantic Fleet Public Affairs

External links[edit]