Cimarron class oiler (1939)


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 and 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
Armament:

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 and 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: 146,000 barrels (23,200 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. 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.

Contents

Ships

Converted to Sangamon-class escort carriers in 1942:

"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.

Ashtabula, Caloosahatchee and Canisteo were jumboized after the 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.

Importance

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.

References

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