T3 tanker

The T3 tanker, or T3, are a class of sea worthy large tanker ships produced in the United States and used to transport fuel oil, gasoline or diesel before and during World War II, the Korean War and the Vietnam War. The T3 tanker classification is still used today.[1] The T3 tanker has a full load displacement of about 24,830 tons.[2]


T3 tankers are about 500 to 600 feet (150 to 180 m) in length and are able to sustain a top speed from 15 to 18 knots (28 to 33 km/h; 17 to 21 mph). The T3 tanker is larger, and usually faster, than a T2 tanker. The hull designation AOG is used by the US Navy to denote that the ship is a T3 gasoline tanker. The AO designation denotes that the ship is a T3 fleet oiler, also referred to as a replenishment oiler (AOR).

Most of the T3 ships were built for private companies and named by the manufacturer. Some T3 tankers were built for or sold to the US Navy, which were renamed after Native Americans, rivers and lakes. T3 tankers are operated by the US Navy, War Shipping Administration and United States Maritime Commission.

The T3 tanker can carry from 113,800 to 200,000 barrels (18,090 to 31,800 m3) of oil. Some T3 tankers were used to transport other goods like black oil-crude oil and chemicals. T3s are also called liquid cargo carriers. The T3 tanker has a full load displacement of about 24,830 tons.[2]

Each T3 has emergency life rafts on the boat deck. The ships have cargo booms and piping to load and unload fuel. During wartime, the T3 ships were armed for protection with deck guns, mainly for anti-aircraft purposes. A typical ship may have one single 3-inch (76 mm)/50 caliber dual-purpose gun, two 40 mm (1.6 in) guns and three single 20 mm (0.8 in) cannons. T3 ships normally carry 81 to 304 crew members. If operating as a United States Merchant Marine ship, the crew would be a mix of civilian Merchant Marines and US Navy Armed Guards to man the deck guns.[3][4][5][6][7][8][9]

The World War II T3-class tankers were considered large for their day, but are small compared to modern oil tankers. Among "supertankers", the ultra large crude carrier is over 300,000 metric tons and the very large crude carrier is over 200,000 metric tons.

The attack on Pearl Harbor brought up an urgent need for aircraft carriers. This led to some T3 tankers being converted to escort carriers. USS Suwannee is an example of a T3 tanker, hull AO-33, that was rebuilt to be an escort carrier. The T3 tanker's size and speed made it a useful escort carrier. There were two classes of T3 hull carriers: the Sangamon and Commencement Bay classes.[10][11][12]


T3 tanker design characteristics
Design & class Propulsion Power Speed (max) Length × beam × draft Gross register tonnage Tankage
T3-S-A1 tanker, Chiwawa-class oiler 2 × steam turbine, single screw 7,700 shp (5,700 kW) 15 kn (28 km/h; 17 mph) 501 ft × 68 ft × 29.6 ft (152.7 m × 20.7 m × 9.0 m) 9,880 133,800 bbl (21,270 m3)
T3-S2-A1 tanker, Cimarron-class oiler 4 × turbine, twin screws 13,500 shp (10,100 kW) 18 kn (33 km/h; 21 mph) 553 ft × 75 ft × 32 ft (168.6 m × 22.9 m × 9.8 m) 11,335 146,000 bbl (23,200 m3)
T3-S2-A3 tanker, Ashtabula class geared turbines, twin screws 30,400 shp (22,700 kW) 18.3 kn (33.9 km/h; 21.1 mph) 553 ft × 75 ft × 32 ft (168.6 m × 22.9 m × 9.8 m) 7,423 146,000 bbl (23,200 m3)
T3-S2-A3 "jumboized" 644 ft × 75 ft × 36 ft (196 m × 23 m × 11 m) 12,840
T3-S-AZ1 tanker 5-cylinder two-cycle oil engine, single screw 7,500 shp (5,600 kW) 15.5 kn (28.7 km/h; 17.8 mph) 547 ft × 70 ft (167 m × 21 m) 11,401
T3-S-B tanker 2 × steam turbines, single screw 7,700 shp (5,700 kW) 14 kn (26 km/h; 16 mph) 515.9 ft × 70 ft (157.2 m × 21.3 m) 11,016 140,000 bbl (22,000 m3)


  • T3-S-A1 tanker: Despite the confusing T3 designation, the T3-S-A1s built by Bethlehem Sparrows Point for Standard Oil of New Jersey were identical to the original T2 tankers except for having less-powerful engines. 25 of this design were ordered by the Maritime Commission, of which 5 became US Navy oilers as the Chiwawa-class oiler. Built by Bethlehem Steel in Sparrows Point, Maryland. (1939 design was a MC-N).
  • T3-S2-A1 tanker: A total of 17 were completed by: Bethlehem Steel Company, Sparrows Point, Maryland; Federal SB & DD Co. of Kearny, New Jersey; Newport News SB & DD Co. of Newport News, Virginia; and Sun SB & DD Co. of Chester, Pennsylvania. They were first commissioned by the US Navy in 1943 as the Cimarron-class oiler, with some converted to escort carriers (CVE). They had a crew of 304 and a range of 12,100 nautical miles (22,400 km; 13,900 mi). Armaments for AO-22 through 33 consisted of: 4 × 5-inch/38 caliber guns, 4 × twin 40 mm gun mounts and 4 × twin 20 mm gun mounts. AO-51 and later were armed with: 1 × 5-inch/38 caliber gun, 4 × 3-inch/50 caliber guns, 4 × twin 40 mm gun mounts and 4 × twin 20 mm gun mounts.
  • T3-S2-A3 tanker: Most of these tankers were "jumboized" in 1964–1965, extending the length from 553 to 644 feet (169 to 196 m), consequently increasing the capacity, tonnage and draft. Jumboized Cimarron-class oilers were reclassed as Ashtabula-class oilers. Crew: 304 (US Navy) or 108 (civilians and US Navy guards). Armament: 1 × 5-inch/38-caliber gun, 4 × 3-inch/50-caliber guns, 4 × twin 40 mm antiaircraft guns and 4 × twin 20 mm antiaircraft guns. Ships in class: Ashtabula, Mispillion, Navasota, Passumpsic, Pawcatuck and Waccamaw. Built by Sun Shipbuilding & Drydock Co..
  • T3-S-AZ1 tanker: Only one in class: Brandywine, built by Sun Ship, launched in August 1943.
  • T3-S-B tanker: Crew: 50 and 31 US Navy Armed Guards. Armament: 1 × 5-inch (130 mm) gun, 1 × 3-inch (76 mm) gun and 20 mm guns, commissioned 1943. Two sub classes: T3-S-BF1 and T3-S-BZ1:
    • T3-S-BF1 Five built in 1943 and 1944: first in class Pan-Pennsylvania, Bulklube, Bulkfuel, Bulkcrude and Bulkero by Welding Shipyards Inc. in Norfolk, Virginia.
    • T3-S-BZ1 Completed three ships: SS Phoenix, SS Nashbulk and SS Amtank. Built in 1943 and 1944 by Welding Shipyards Inc. in Norfolk, Virginia.

Notable incidents

  • USS Pan Pennsylvania, a Type T3-S-BF1 tanker, on 16 April 1944 was sunk off Nantucket by a torpedo from U-boat U-550 commanded by Klaus Hänert. Pan-Pennsylvania was steaming from New York Harbor on the afternoon of 15 April 1944 as part of convoy CU-21, going to England with 140,000 barrels (22,000 m3) of 80-octane aviation fuel. She had a crew of 50 men and 31 members of the Naval Armed Guard. The 28 merchant ships of CU-21 were accompanied by Escort Flotilla 21.5, which consisted of six destroyer escorts.[14]
  • USS Mississinewa, a T3-S2-A1 tanker, on 20 November 1944 was sunk near Ulithi Island after being hit by a Japanese Kaiten manned torpedo.[15]
  • USS Shabonee, a T3-S-A1 tanker, was sold to the US Navy and renamed USS Escalante (AO-70). In 1947 she was sold and renamed SS George MacDonald. On 30 June 1960 she sank 165 miles (266 km) east of Savannah, Georgia after an engine fire on 27 June.[16][17]
  • Lake Charles, a T3-S-A1 renamed Capri, ran aground on Molasses Reef, Florida (25.07 N, 80.22 W) on 27 April 1963. She was a total loss.[18]
  • Brandywine, a T2-SE-A1 renamed Atlantic Sun, was damaged in 1962 and scrapped.[19]
  • Phoenix, a T3-S-BZ1, first in her class, was badly damaged in a collision with Pan Mass on 6 June 1953, resulting in a total loss.[20]

See also


  • Wildenberg, Thomas (1996). Gray Steel and Black Oil: Fast Tankers and Replenishment at Sea in the U.S. Navy, 1912–1995. Annapolis, Maryland: Naval Institute Press. Retrieved 28 April 2009.
  • hazegray.org, Ships of Mare Island
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