USNS Mizar (MA-48/T-AGOR-11/T-AK-272) was a vessel of the United States Navy. She was named after the star Mizar. Cargo ship Mizar was built as a small ice-strengthened, double hull, cargo ship of the Eltanin class on a Maritime Administration type (C1-ME2-13a) hull, by Avondale Marine Ways, Inc. from January 1957. She entered service on March 7, 1958, and served as part of the Military Sea Transportation Service (MSTS), working around Canada and Greenland, with a single voyage to Antarctica in 1961. Naval Research Laboratory The loss of the on April 10, 1963, and problems handling heavy search equipment over the side from in 1963 drove the Naval Research Laboratory (NRL) requirement for a larger, more capable ship than the usual oceanographic research type. A search for a candidate ship, capable of being modified for an inboard center well, led to selection of Mizar in late 1963. In 1964 Mizar's successful search for the sunken submarine, before modification for the desired center well, further demonstrated the need for a sheltered work space with heavy lift and towing capability. Center well NRL's previous vessel with a center well, , provided experience and some problems to avoid in the Mizar design. The two major problems with that installation were wave action in the well that damaged the bulkheads until reinforced and air pressure caused by wave action in the well that forced the deck doors off their tracks. The location of the number two hatch straddling the ship's center section made a center well through even the double bottom feasible. A well long and wide with curved fore and aft ends to reduce wave pounding within was installed. The keel level opening was reduced to one of long and wide. A flush mounted, water tight hydraulic door of two parts, one fore and one aft, closed the well at the main deck level. Three diameter cable sheaves installed in a carriage, within which towed devices would be contained for lowering and raising, and extending below the keel allowed towing of heavy equipment without exposure on open decks. The system had a capacity of 12 tons. Large "breather" ducts from the well relieved air pressure caused by wave action within when the doors were closed. All was enclosed by a housing allowing all weather protection for operators. Mizar went into the Philadelphia Naval Shipyard in late 1965 with the installation of the well being