USS Mizar (AF-12) was the United Fruit Company fruit, mail and passenger liner Quirigua that served as a United States Navy Mizar-class stores ship in World War II.

Quirigua was one of six fast turbo-electric transmission driven ships built for United Fruit's subsidiary United Mail Steamship Company, the first of its ships built in the U.S., to take advantage of subsidies and mail contracts. The ships were refrigerated fruit carriers with substantial passenger capacity and, as a result of the mail contract connection, termed "Mail class" by the line. Three were built by Newport News Shipbuilding and three by Bethlehem Shipbuilding Corporation of Quincy, Massachusetts. Quirigua was the second of the group built by Bethlehem Shipbuilding. Three ships served the Pacific routes and three the Atlantic routes with Quirigua operating out of New York.

During the buildup of United States defenses in preparation for war, the ship was acquired for use by the Navy under a bareboat charter as refrigerated stores ships on 2 June 1941 that was administered by the War Shipping Administration (WSA) on creation of that organization in early 1942. The ship was commissioned USS Mizar and served in the Atlantic and Pacific. Mizar decommissioned and returned to WSA at Baltimore 1 April 1946 then, with United Fruit operating the vessel under a General Agency Agreement with WSA, the ship arrived in August 1946 at Bethlehem Steel's Staten Island Shipyard for re-conversion to former use. The conversion complete, the ship was returned to its owner 15 February 1947 as Quirigua.

United Fruit transferred the ship to its British subsidiary Elders and Fyffes where it served as Samala, after an earlier Fyffes ship, until scrapping 1964.

Quirigua was one of six ships ordered in August 1930 and built under the Merchant Marine Act of 1928 (Jones-White Act) for the United Mail Steamship Company, a subsidiary of the United Fruit Company, designed with specialized cooling and handling arrangements for transporting bananas. Three of the ships were built by Bethlehem Shipbuilding Corporation, Quincy, Massachusetts with Quirigua being the second, preceded by Antigua and followed by Veragua. The other three, built by Newport News Shipbuilding, were Chiriqui, Peten (originally Segovia, later Jamaica) and, the first of the six to be launched, Talamanca. The six ships were of the same basic design with specific developments of that design left to the two builders. The six ships were the first for the line not built in Europe. Construction in U.S. yards was a result of the Merchant Marine Act and more liberal government support in the form of mail contracts.

The carriage of fruit was the primary purpose of the ships, though passengers, mail and general cargo were important components. The design was driven by the special requirements of a refrigerated fruit carrier, in effect an enhanced "banana boat", in which refrigeration and banana handling capability was incorporated in the basic design. An expensive feature, required by the government for loans, was the "two compartment" rule requiring the ship to stay afloat with any two compartments flooded. The ships were subdivided into nine compartments by eight watertight bulkheads. As a result of shorter compartments more refrigeration equipment was required driving costs and requiring larger ships than the former "banana boats" for the same amount of fruit cargo. Sixteen refrigerated cargo compartments were located in two cork insulated holds forward and two aft of the central superstructure with York Ice Machinery Corporation refrigeration units located below the orlop deck aft.

The contract required minimum speed of 17.5 kn (20.1 mph; 32.4 km/h), though in trials some of the ships made over 19 kn (22 mph; 35 km/h), and guaranteed 10,500 horsepower. That was met with a turbo-electric transmission system with four Babcock & Wilcox oil fired boilers providing steam for two turbine driven General Electric (GE) generators and auxiliary generator sets for ship's power. Propulsion was by two 3,150 volt, 4,200 kilowatt, 5,500 horsepower at 125 revolutions GE electric motors driving twin 15 ft 6 in (4.7 m), 3 blade screws. Ship's service electricity was provided by three GE turbine generator sets, 500 kilowatts each with 120 and 240 volt service, driven by steam from the boilers to power electric motors on auxiliaries and deck machinery as well as the electrical systems for quarters and navigation. All auxiliaries normally required at sea were electric motor driven.

The two yards were allowed to develop specific designs from the design characteristics established for the six ships. As a result, there are slight differences in principal characteristics between the Newport News and Bethlehem built ships beyond the normal small differences in measurement type, agency and time. Comparable figures for Bethlehem's lead ship, Quirigua's yard predecessor Antigua, are given as being 447 ft 10 in (136.5 m) overall length, 428 ft 9 in (130.7 m) length on 24 ft (7.3 m) waterline, 415 ft (126.5 m) length between perpendiculars, 60 ft (18.3 m) molded beam, 34 ft 9 in (10.6 m) depth molded to upper deck, 24 ft (7.3 m) molded, 10,928 tons displacement at the design waterline, 7,035 GRT, 3,523 NRT, 240,070 cu ft (6,798.0 m³) refrigerated cargo capacity, 5,370 cu ft (152.1 m³) for baggage and mail, 1,405 tons of fuel oil and 730 tons fresh water capacity. Accommodations were designed for 113 persons. Bethlehem Shipbuilding designed the passenger spaces, using a modern design for both stateroom and public spaces with the exception of two "period" style rooms, the dining room and library. Both passenger and crew spaces were steam heated and provided with mechanical ventilation.