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.

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.