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Cimarron-class oiler (1939)
USS Cimarron (AO-22) Norfolk Feb1942.jpg
USS Cimarron (AO-22), lead ship of the class in February 1942
Class overview
Operators:  United States Navy
Built: 1938–1945
In commission: 1939–1992
Completed: 35, later 4 converted to escort carriers
Lost: 2
Retired: 29
General characteristics
Class & type: Cimarron-class oiler
Displacement: 7,470 long tons (7,590 t) light
24,830 long tons (25,228 t) full load
Length: 553 ft (169 m)
Beam: 75 ft (23 m)
Draft: 32 ft 4 in (9.86 m)
Propulsion: Geared turbines, twin screws, 30,400 shp (22,669 kW)
Speed: 18 knots (21 mph; 33 km/h)
Range: 12,100 nmi (22,400 km; 13,900 mi)
Capacity: 146,000 barrels (23,200 m3)
Complement: 304

AO-22 through 33:
• 4 × 5"/38 caliber guns
• 4 × twin 40 mm gun mounts
• 4 × twin 20 mm gun mounts

AO-51 and later:
• 1 × 5"/38 caliber gun
• 4 × 3"/50 caliber guns
• 4 × twin 40 mm gun mounts
• 4 × twin 20 mm gun mounts
General characteristics
Class & type: Ashtabula-class oiler (Jumboized Cimarron)
Displacement: 12,840 tons (light);
33,987 tons (full load)
Length: 644 ft (196 m)
Beam: 75 ft (23 m)
Draft: 34 ft 9 in (10.59 m)
Installed power: 30,400 hp (22,700 kW)
Propulsion: geared turbines, four boilers, twin screws
Speed: 16 knots (30 km/h)
Capacity: 180,000 barrels (29,000 m3) of fuel oil
Complement: 304 (as USS)
Crew: 108 civilians plus U.S. Navy detachment (as USNS)
Notes: "Jumboization" involved the lengthening of the hull and installation of additional cargo capacity during 1965–66

The Cimarron class oilers were an underway replenishment class of oil tankers which were first built in 1939 as "National Defense Tankers," United States Maritime Commission Type T3-S2-A1, designed "to conform to the approved characteristics for naval auxiliaries in speed, radius and structural strength", anticipating their militarization in the event of war. "Tentative plans had been reached with the Standard Oil Company of New Jersey to build ten high-speed tankers with the government paying the cost of the larger engines needed for increased speed. By the first week in December [1937], Standard Oil had solicited and received bids from a number of yards providing for the construction of a number of 16,300-ton (deadweight) capacity tankers. Bids were requested for two versions: a single-screw design of 13 knots and a twin-screw design of 18 knots. The price difference between the two would be used to establish the government's cost subsidy for greater speed. Plans and specifications for both designs were prepared for Standard Oil by naval architect E. L. Stewart. It seems certain that the design for the 18-knot tanker (Standard Oil Co. of New Jersey Design No. 652 NDF) evolved out of the bureau's (C&R) design for a fleet oiler." [1]

Three of the original twelve ships were commissioned directly into the Navy at launch in 1939; the remainder entered merchant service with Standard Oil of New Jersey and Keystone Tankships before being acquired under the Two-Ocean Navy Act of July 1940. A further eighteen were built for the Navy between 1943 and 1946, with five additional units, sometimes called the Mispillion class, built to the slightly larger Type T3-S2-A3 design.

Four of the Cimarrons were converted to escort carriers (CVE) in 1942; two others were sunk by enemy action.


Converted to Sangamon-class escort carriers in 1942:

  • USS Sangamon (CVE-26); ex-Esso Trenton, launched 1939, commissioned 1940 as AO-28, decommissioned 1945, sold for commercial service 1948
  • USS Suwannee (CVE-27); ex-Markay, launched 1939, commissioned 1941 as AO-33, decommissioned 1947, sold for scrap 1961
  • USS Chenango (CVE-28); ex-Esso New Orleans, launched 1939, commissioned 1941 as AO-31, decommissioned 1946, sold 1960
  • USS Santee (CVE-29); ex-Seakay, launched 1939, commissioned 1940 as AO-29, decommissioned 1946, struck 1959, scrapped 1960

"Mispillion" and "Ashtabula" classes

There is some controversy about the MARAD Type T3-S2-A3 oilers being a class of their own, the Mispillion-class. This is further complicated by the fact that these ships were jumboized in the 1960s, together with Ashtabula (AO-51), Caloosahatchee (AO-98), and Canisteo (AO-99), for some then comprising the Ashtabula-class - sometimes with or without the Mispillions. Adding to the confusion, some sources refer to the 18 war-construction repeat Cimarrons as the Ashtabula-class.

  • USS Mispillion (AO-105); launched & commissioned 1945, jumboized 1965, transferred to MSC 1974, retired 1990, struck 1995, NDRF, sold for scrapping Dec. 3, 2011
  • USS Navasota (AO-106); launched 1945, commissioned 1946, jumboized 1964, transferred to MSC 1975, retired 1991, struck 1992, sold for scrapping 1995
  • USS Passumpsic (AO-107); launched 1945, commissioned 1946, jumboized 1965, transferred to MSC 1973, retired, struck & sold for scrapping 1991
  • USS Pawcatuck (AO-108); launched 1945, commissioned 1946, jumboized 1965, transferred to MSC 1975, retired & struck 1991, sold for scrapping 2005
  • USS Waccamaw (AO-109); launched 1945, commissioned 1946, jumboized 1965, transferred to MSC 1975, retired 1989, struck 1991, sold for scrapping 2005


From 1964 through 1967, eight of the T3 type oilers were "jumboized" in order to increase their capacity to 180,000 barrels, which the Navy considered the amount necessary to support a supercarrier and its jet air wing's fuel needs. This jumboization was done by cutting the ships in two with cutting torches, then the aft section was pulled away, and new mid-body moved in and welded to the bows and sterns. After many other cutting and welding modifications a new long ship was created; a helipad was also fitted forward. Ashtabula, Caloosahatchee and Canisteo were jumboized after the five Mispillions and were given a limited capacity for ammunition and dry stores as well as a new midships superstructure and full scantlings, whereas AO-105 through 109 retained their shelter-deck configuration.


The US Navy's mastery of underway replenishment and its ability to refuel the fleet at sea without returning to port was a major factor in its successful operations against the Japanese during the Second World War. As the largest and fastest of the Navy's oilers, the Cimarrons were the principal class employed in direct support of the task forces. Many of the Cimarron class continued to sustain this function through the Korean and Vietnam wars as well, with the "jumbos" serving right up to the Persian Gulf War.

US Navy captains who had flight status ("wings") were eligible to command aircraft carriers, but it was a prerequisite that the officer in question first have a "deep-draft" command; accordingly the Navy assigned these officers to oilers which had a similar draft.


  1. 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 2013-10-16. 

This article incorporates text from the public domain Dictionary of American Naval Fighting Ships.

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