The ''Suamico'' class were a class of 25
United States Navy oiler
A replenishment oiler or replenishment tanker is a naval auxiliary ship with fuel tanks and dry cargo holds which can supply both fuel and dry stores during underway replenishment (UNREP) at sea. Many countries have used replenishment oilers.
The ...
s during World War II. Built to the Maritime Commission T2-SE-A1 (''Suamico'' class), -A2 (''Escambia'' class) and -A3 (''Cohocton'') designs, they used
turbo-electric transmission
A turbo-electric transmission uses electric generators to convert the mechanical energy of a turbine (steam or gas) into electric energy, which then powers electric motors and converts back into mechanical energy that power the driveshafts.
Tur ...
, obviating the need for reduction gearing which was a major issue in US mass-production shipbuilding.
Construction
The ''Suamico''s
Just before the war the
United States Maritime Commission
The United States Maritime Commission (MARCOM) was an independent executive agency of the U.S. federal government that was created by the Merchant Marine Act of 1936, which was passed by Congress on June 29, 1936, and was abolished on May 24, 195 ...
had developed a standardized tanker design, the
T2, which could be mass-produced in time of war, and militarized as needed for naval auxiliaries. The T2 was given sufficient engine power to attain , which the Navy considered the minimum required for a fleet oiler.
The T2 and its variants (see ) however used conventional geared steam turbine propulsion, and with the massive expansion of US shipbuilding, a production bottleneck developed: the limited availability of the precision machinery needed to manufacture reduction gearing. The
Sun Shipbuilding and Drydock Company of Chester, Pennsylvania worked around this problem by designing a T2 variant which used turbo-electric propulsion; that is, the steam turbine ran a generator, which in turn powered electric drive motors without the need for gearing.
[Turbo-electric propulsion was not new; the ]battleship
A battleship is a large armored warship with a main battery consisting of large caliber guns. It dominated naval warfare in the late 19th and early 20th centuries.
The term ''battleship'' came into use in the late 1880s to describe a type of ...
had been built with it in 1915, as were five more battleships and two aircraft carrier
An aircraft carrier is a warship that serves as a seagoing airbase, equipped with a full-length flight deck and facilities for carrying, arming, deploying, and recovering aircraft. Typically, it is the capital ship of a fleet, as it allows a ...
s Compared to conventional geared turbines turbo-electric systems produced less power for the same size and weight, so Sun's T2-SE (steam-electric)-A1 design could only develop 6,000 shaft horsepower for 14 knots, but since commercial tankers typically only did 12–13 knots this was acceptable. Acknowledging the practicality of the design for merchant service, the Maritime Commission ordered 72 T2-SE-A1s from four shipyards in May 1941. Ultimately 536 T2-SEs would be built, the most-produced tanker design in history.
On 9 June 1942,
Admiral Nimitz indicated an immediate need for four more fleet oilers. The War Shipping Board requisitioned the last remaining T2 and T2-A tankers still in commercial service,
''Catawba'' and
''Aekay'', and, with reservations given their limited speed, two nearly-complete Sun T2-SE-A1s, ''Harlem Heights'' and ''Valley Forge.'' These were commissioned as USS ''Suamico'' (AO-49) and ''Tallulah'' (AO-50). In August, with the fourteen repeats of the big still a year from completion, the Navy took over the next two T2-SEs off Sun's ways, ''Oriskany'' and ''Stillwater,'' renamed ''Pecos'' (AO-65) and ''Cache'' (AO-67). On 7 August the Auxiliary Vessels Board recommended that the Navy add two oilers per month for a period of six months. While fifteen of the 15.3-knot T3-S-A1 type had been ordered by the Maritime Commission, only five (the ) would be completed in time, and so the Navy filled out the requirement with another seven T2-SE-A1s, AO-73 through 79, the first of which were acquired on the last day of 1942.
The ''Escambia''s
During the spring and summer of 1942, a period German
U-boat
U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare role ...
captains called "the happy time," tankers were being sunk in the Atlantic faster than they could be built. In response, on 27 July the Maritime Commission decided that the new
Marinship
Marinship Corporation was a shipbuilding company of the United States during World War II, created to build the shipping required for the war effort. Founded in 1942, the shipyard built 93 cargo ships and oil tankers, before ending operations 1 ...
yard at Sausalito, California, created to produce
Liberty ship
Liberty ships were a class of cargo ship built in the United States during World War II under the Emergency Shipbuilding Program. Though British in concept, the design was adopted by the United States for its simple, low-cost construction. Mass ...
s, would construct T2-SE tankers instead, with an initial order of 22. However, there simply were not enough of the specified generator plants available. On the other hand, General Electric indicated its ability to provide the larger turbo-electric plants designed for the P2-SE2-R1
Admiral-class fast transports, and Marinship's naval architects modified the original Sun design to make room for the larger installation. The Marin T2-SE-A2's engineering spaces were cramped, but it all fit; better yet, the new design was capable of speeds in excess of . By the end of the year the Navy, unenthusiastic about the slower ''Suamico''s, was eager to acquire the more powerful new version and requisitioned the first nine, which were launched starting in April 1943 and after conversion as fleet oilers started commissioning in October, as AO-80, USS ''Escambia'', through AO-88.
The Maritime Commission followed its initial order of 22 T2-SE-A2s with another for 18 more; the Navy would acquire six of these as AO-91 through 96. By the time these started entering service in late 1944 the Navy was finding that fresh water was becoming more of a problem in the Pacific than fuel; accordingly ''Pasig'' and ''Abatan'' were converted to water-distilling ships (AW-3 and 4), and ''Soubarissen'' into a water tanker.
The A3s
On 16 October 1944 the
Chief of Naval Operations
The chief of naval operations (CNO) is the professional head of the United States Navy. The position is a statutory office () held by an admiral who is a military adviser and deputy to the secretary of the Navy. In a separate capacity as a memb ...
recommended that the Maritime Commission building program for the last half of 1945 be modified to provide for the construction of nine additional oilers for the Navy. On 2 November 1944 the MC added to its program the construction of four ships at Marinship to the 10,000-horsepower T2-SE-A3 design together with five T3s at
Bethlehem Steel
The Bethlehem Steel Corporation was an American steelmaking company headquartered in Bethlehem, Pennsylvania. For most of the 20th century, it was one of the world's largest steel producing and shipbuilding companies. At the height of its succe ...
. The T2-SE-A3 type was essentially an A2 built to Navy standards from the start rather than being modified later (converting a civilian tanker to a Navy fleet oiler represented an additional 4–6 months' work after delivery). The last three ships were completed without these features, after the Navy canceled them in the waning days of the war.
Postwar service
All of the oilers of the class were decommissioned to reserve in 1946; however all were reactivated for tanker duties with civilian crews by the
Naval Transport Service
Military Sealift Command (MSC) is an organization that controls the replenishment and military transport ships of the United States Navy. Military Sealift Command has the responsibility for providing sealift and ocean transportation for all US m ...
and its successor the
Military Sea Transportation Service
Military Sealift Command (MSC) is an organization that controls the replenishment and military transport ships of the United States Navy. Military Sealift Command has the responsibility for providing sealift and ocean transportation for all US m ...
in 1947–1950, except for ''Saranac'', which had been converted to a floating electric power plant to supply the naval base at Guam, and ''Ponaganset'', which broke in half and sank during her pre-reactivation overhaul. The ''Escambia''s were retired to the
National Defense Reserve Fleet
The National Defense Reserve Fleet (NDRF) consists of ships of the United States of America, mostly merchant vessels, that have been "mothballed" but can be activated within 20 to 120 days to provide shipping during national military emergencies ...
by the end of the 1950s, while the somewhat more economical ''Suamico''s soldiered on through the
Vietnam War
The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
; ''Cowanesque'' struck a reef and foundered off Okinawa in 1972. Because of their 7.5 megawatt generating capacity, six of the ''Escambia''s were transferred to the
United States Army
The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...
and converted to floating power plants in 1965–66, serving in that role in Vietnam. When ''Saugatuck'' went to the
breakers in 2006 she was the last survivor of the Navy's Type T2 oilers.
Ships of the class
See also
*
United States Navy oiler
A replenishment oiler or replenishment tanker is a naval auxiliary ship with fuel tanks and dry cargo holds which can supply both fuel and dry stores during underway replenishment (UNREP) at sea. Many countries have used replenishment oilers.
The ...
*
T-2 Tanker
The T2 tanker, or T2, was a class of oil tanker constructed and produced in large quantities in the United States during World War II. Only the T3 tankers were larger "navy oilers" of the period. Some 533 T2s were built between 1940 and the end o ...
Notes
{{Suamico class fleet replenishment oiler
Auxiliary replenishment ship classes
Turbo-electric steamships