Suamico class oiler
Encyclopedia
The Suamico class were a class of 25 oilers
of the United States Navy during WWII. Built to the Maritime Commission T2-SE-A1 (Suamico class), -A2 (Escambia class) and -A3 (Cohocton) designs, they used turbo-electric
propulsion, obviating the need for reduction gearing, a major issue in US mass-production shipbuilding.
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 16.5 knots, which the Navy considered the minimum required for a fleet oiler.
The T2 and its variants (see Kennebec class
) 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. 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 18-knot Cimarron class 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 August 7 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 Chiwawa class
) 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.
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
yard at Sausalito, California, created to produce Liberty ship
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 10,000hp 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 15 knots. By the end of the year the Navy, unenthusiastic about the slower Suamicos, 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-A2's 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 T2-SE-A3 type was essentially an A2 built to Navy standards from the start rather than being modified later. The last 3 ships were completed without these features, after the Navy canceled them in the waning days of the war.
by the end of the 1950s, while the somewhat more economical Suamicos soldiered on through the Vietnam War; Cowanesque struck a reef and foundered off Okinawa in 1972. Because of their 7.5 megawatt generating capacity, six of the Escambias were transferred to the Army 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.
United States Navy oiler
In the United States Navy, an Oiler is a Combat Logistics ship that replenishes other ships with fuel and in some cases food, mail, ammunition and other necessities while at sea, in a process called Underway Replenishment or UNREP...
of the United States Navy during WWII. Built to the Maritime Commission T2-SE-A1 (Suamico class), -A2 (Escambia class) and -A3 (Cohocton) designs, they used turbo-electric
Turbo-electric
A turbo-electric transmission uses electric generators to convert the mechanical energy of a turbine into electric energy and electric motors to convert it back into mechanical energy to power the driveshafts....
propulsion, obviating the need for reduction gearing, a major issue in US mass-production shipbuilding.
The Suamicos
Just before the war the United States Maritime CommissionUnited States Maritime Commission
The United States Maritime Commission was an independent executive agency of the U.S. federal government that was created by the Merchant Marine Act of 1936, passed by Congress on June 29, 1936, and replaced the U.S. Shipping Board which had existed since World War I...
had developed a standardized tanker design, the T2
T2 tanker
The T2 tanker, or T2, was an oil tanker constructed and produced in large quantities in the United States during World War II. The largest "navy oilers" after the T3s at the time, nearly 500 of them were built between 1940 and the end of 1945....
, 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 16.5 knots, which the Navy considered the minimum required for a fleet oiler.
The T2 and its variants (see Kennebec class
Kennebec class oiler
The Kennebec-class oilers were sixteen United States Navy medium oilers built during World War II to three related designs at Bethlehem Sparrows Point Shipyard of Sparrows Point, Maryland and Sun Shipbuilding & Drydock Co. of Chester, Pennsylvania, all of which survived the war...
) 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
Turbo-electric
A turbo-electric transmission uses electric generators to convert the mechanical energy of a turbine into electric energy and electric motors to convert it back into mechanical energy to power the driveshafts....
propulsion; that is, the steam turbine ran a generator, which in turn powered electric drive motors without the need for gearing. 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
Nimitz
Nimitz can refer to:* Fleet Admiral Chester W. Nimitz USN, * Nimitz class aircraft carrier of US Navy aircraft carrier* USS Nimitz , the lead ship of the above class* Nimitz High School, Houston, Texas...
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
USS Neosho (AO-48)
|-External links:...
and Aekay
USS Neches (AO-47)
USS Neches was a in the United States Navy during World War II and the Vietnam War. She was the second U.S. Navy ship named for the Neches River in eastern Texas....
, 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 18-knot Cimarron class 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 August 7 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 Chiwawa class
Chiwawa class oiler
The Chiwawa-class oilers were United States Navy oilers of the T3-S-A1 design built during World War II at Bethlehem Sparrows Point Shipyard of Sparrows Point, Maryland...
) 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 Escambias
During the spring and summer of 1942, a period German U-boatU-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...
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
Marinship Corporation was a shipbuilding company of the United States during World War II, created to build the shipping required for the war effort...
yard at Sausalito, California, created to produce Liberty ship
Liberty ship
Liberty ships were cargo ships built in the United States during World War II. Though British in conception, they were adapted by the U.S. as they were cheap and quick to build, and came to symbolize U.S. wartime industrial output. Based on vessels ordered by Britain to replace ships torpedoed by...
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 10,000hp turbo-electric plants designed for the P2-SE2-R1 "Admiral" class
P2 transport
The P2 transport was a United States Maritime Commission design for a passenger ship which could be readily converted into a troop transport. Three variants of the design were built, the P2-SE2-R1 , P2-S2-R2 , and P2-SE2-R3 .-Admirals:Ten P2-SE2-R1 ships were ordered by the Maritime Commission...
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 15 knots. By the end of the year the Navy, unenthusiastic about the slower Suamicos, 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-A2's 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 Oct 44 the CNO 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 Nov 44 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 SteelBethlehem Steel
The Bethlehem Steel Corporation , based in Bethlehem, Pennsylvania, was once the second-largest steel producer in the United States, after Pittsburgh, Pennsylvania-based U.S. Steel. After a decline in the U.S...
. The T2-SE-A3 type was essentially an A2 built to Navy standards from the start rather than being modified later. The last 3 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 and its successor the Military Sea Transportation Service in 1947-50, 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 Escambias were retired to the National Defense Reserve FleetNational Defense Reserve Fleet
The National Defense Reserve Fleet consists of "mothballed" ships, mostly merchant vessels, that can be activated within 20 to 120 days to provide shipping for the United States of America during national emergencies, either military or non-military, such as commercial shipping crises.The NDRF is...
by the end of the 1950s, while the somewhat more economical Suamicos soldiered on through the Vietnam War; Cowanesque struck a reef and foundered off Okinawa in 1972. Because of their 7.5 megawatt generating capacity, six of the Escambias were transferred to the Army 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
| Name | Original name | Commissioned | USNS service | Fate |
|---|---|---|---|---|
| T2-SE-A1 (Sun Shipbuilding & Drydock, Chester, PA) | ||||
| Harlem Heights | 10 Aug 42 | 1948-1974 | Struck 1974; scrapped 1975 | |
| Valley Forge | 5 Sept 42 | 1949-1975 | Struck 1986, scrapped 1987 | |
| Oriskany | 5 Oct 42 | 1950-1974 | Struck 1974; scrapped 1975 | |
| Stillwater | 3 Nov 42 | 1948-1973 | Struck 1986, scrapped 1987 | |
| Kings Mountain | 5 Mar 43 | 1949-1976 | Struck and scrapped 1987 | |
| Cowpens | 22 Feb 43 | |||
| To floating power plant 1946, reclassified YFP-9 1954. Struck 1956, sold 1957 (Somerset) | ||||
| Newtown | 19 Feb 43 | 1948-1974 | Struck and scrapped 2006 | |
| Louisburg | 9 Apr 43 | 1949-1976 | Struck 1986, scrapped 1988 | |
| Fort Necessity | 20 Apr 43 | 1949-1974 | Struck 1974, scrapped 1975 | |
| Eutaw Springs | 27 Apr 43 | 1949-1972 | Struck 1980 | |
| Fort Duquesne | 1 May 43 | 1950-1972 | Sank off Okinawa 1972 | |
| T2-SE-A2 (Bechtel Marinship, Sausalito, CA) | ||||
| * | 28 Oct 43 | 1950-1957 | To Army as floating power plant 1966, scrapped 1971 | |
| * | 4 Dec 43 | 1950-1959 | To Army as floating power plant 1965, sold to RVN 1974 | |
| * | Lackawapen | 14 Jan 44 | 1950-1958 | To Army as floating power plant 1966, scrapped 1971 |
| 3 Feb 44 | 1950-1959 | Struck and sold 1959 (Seatrain Oregon, Transchamplain), scrapped 1980 | ||
| 9 Mar 44 | 1949-1959 | Struck 1959, scrapped 1975 | ||
| 30 Apr 44 | 1949-1957 | Struck and sold 1957 (Seatrain Florida), to NDRF 1975, scrapped 1986 | ||
| 15 May 44 | ||||
| Sank dockside at Boston 1947, wreck scrapped 1949 | ||||
| * | 29 Mar 44 | 1950-1957 | To Army as floating power plant 1966, scrapped 1974 | |
| 16 Apr 44 | 1947-1960 | Sold 1966 (Seatrain Maine), to NDRF 1973, scrapped 2008 | ||
| Mission San Xavier | 28 Aug 44 as AW-3 | |||
| Decommissioned 1955, struck 1960, scrapped 1975 | ||||
| Mission San Lorenzo | 29 Jan 45 as AW-4 | |||
| Decommissioned 1947, struck 1970, SINKEX SINKEX SINKEX or Sink Exercise is a US military term for the test of a weapons system usually involving a torpedo or missile attack of an unmanned target ship. The US Navy sometimes refers to this type of exercise as a HULKEX... 1980 |
||||
| Mission Santa Ana | 5 Jan 45 | 1948-1958 | Struck 1961, scrapped 1982 | |
| Mission Alamo | 25 Feb 45 | 1948-1957 | Struck 1957, sold 1967 (Penn Ranger, Omnium Ranger), scrapped 1978 | |
| * | Mission Los Angeles | 25 Mar 45 | 1950-1959 | To Army as floating power plant 1966, sold to RVN 1974 |
| Mission San Francisco | 20 May 45 | 1948-1957 | To Army as floating power plant 1966, sold to RVN 1974 | |
| T2-SE-A3 (Bechtel Marinship, Sausalito, CA) | ||||
| 25 Aug 45 | 1949-1958 | Sold 1967 (Transoneida), scrapped 1980 | ||
| 1948-1958 | Completed as Oct 1945, struck 1958 | |||
| 1947-1957 | Completed as Oct 1945, struck 1957 | |||
| 1947-1957 | Completed as Oct 1945, sank at New Castle DE 1957 | |||