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USS Pawcatuck (AO 108) after jumboization.

USS Pawcatuck (AO 108) after jumboization.
Click on this photograph for links to larger images of this class.

Class: MISPILLION (AO 105 Jumbo)
Design: SCB Project No. 224 (MC T3-S2-A3 conversion)
Displacement (tons): 34,645 full
Dimensions (feet): 644' oa, 616' pp x 75' x 35.3' full
Armament: (1957-59) 4-3"/50 single mounts; (1973-75, MSC) none
Accommodations: 18 officers, 288 enlisted
Speed (kts.): 18 (15 sustained at full load)
Propulsion (HP): 13,500
Machinery: 2 Westinghouse turbines, 4 boilers, 2 screws

Conversion:
AONameOrdBuilderStart midbodyStart shipCompl
105MISPILLION26 Nov 1963American SB, Lorain, Ohio30 Mar 196416 Apr 19651 Jun 1966
106NAVASOTA7 Mar 1963Puget Sound B&DD/Kawasaki27 May 1963Nov 196328 Dec 1964
107PASSUMPSIC26 Nov 1963American SB, Lorain, Ohio2 Mar 196426 Nov 196415 Dec 1965
108PAWCATUCK26 Nov 1963American SB, Lorain, Ohio1 Jun 196414 Sep 196516 Dec 1966
109WACCAMAW7 Mar 1963Puget Sound B&DD/Kawasaki10 Jun 196329 Feb 196426 Feb 1965

Disposition:
AONameTDecommStrikeDisposalFateMA Sale/Depart
105MISPILLIONTr199015 Feb 19951 May 1999MA/TDec 2011
106NAVASOTATr19912 Jan 199225 Oct 1995Sold--
107PASSUMPSICTr199117 Dec 199118 Dec 1991MA/S19 Dec 1991
108PAWCATUCKTr199121 Sep 19911 May 1999MA/T26 Aug 2005
109WACCAMAWTr198911 Oct 19911 May 1999MA/T26 Aug 2005

Class Notes:
The history of these ships before jumboization is given on the page for the MISPILLION (AO 105) class in the World War II section of this site.

In late 1960 COMSERVPAC submitted a request to add a 60-foot insert plug to AO 22 class oilers to increase their JP5 capacity, and on 15 November 1960 the Ship Characteristics Board asked BUSHIPS for a cost and feasibility study of such a conversion. Following a CNO request to increase the capacity of these ships and modernize them, BUSHIPS decided to investigate the alternative of "jumboizing" them. The jumboizing process consisted of replacing the cargo tank section of a tanker while retaining the bow and stern sections, the latter containing the propulsion plant. Because the Maryland Shipbuilding and Drydock Co. in Baltimore was the originator of the idea of jumboizing T2 and T3 tankers and because they had been the leading yard in actual conversions of this type, two members of the Bureau's Hull Design Branch (Code 440) visited that company on 28 November 1960 to discuss the feasibility of jumboizing the AO 22 class. It was concluded that it was both feasible and desirable to jumboize the AO 22 type, but with a complete new mid-body rather than by inserting a plug as proposed by COMSERVPAC. In their report the BUSHIPS visitors recommended that, in view of the experience of Maryland SB&DD and the present design work load in Code 440, a design contract be awarded to the Baltimore firm, initially to prepare preliminary designs to provide CNO with a spectrum of feasible capacities with estimated speeds and costs, and following the selection by CNO of the desired capacity to prepare contract plans. The contract with Maryland SB&DD to act as design agent for the conversion was concluded in February 1961.

On 24 February 1961 COMSERVLANT submitted to CNO an analysis done jointly with COMSERVPAC of the construction and conversion of fleet oilers that would be required in Fiscal Years 1963-1968. The study showed that the total force could be maintained at 33 ships by jumboizing nine AO-22 class ships and building new ships of the AO, AOR, and AOE types to offset the loss of the remaining AO-22 class ships, all of which would be phased out by 1972. The nine jumboized tankers would have their tank sections replaced and their bow and stern sections repaired and renovated for extended service life in consonance with the FRAM (Fleet Rehabilitation and Modernization) concept. (The existing midship house was also retained.) On 1 March 1961 the Ship Characteristics Board circulated for discussion the initial staff proposed characteristics for an AO 22 class conversion. In the converted ships the sustained speed was expected to remain at about 15 knots but the underway replenishment speed was to be increased from about 12 to 15 knots by adding an independent auxiliary power plant for the replenishing winches and pumps. The pumping capacity was also to be increased, all eight transfer stations were to be tensioned instead of only two of the six stations in the AO 22 class, a cargo deck similar to the one in the AO 143 class was to be provided, and the steering machinery and rudder were to be improved to enhance the maneuverability of the enlarged ship during replenishment. A clear area forward suitable for the pick-up of cargo by a hovering helicopter was also to be provided.

On 21 April 1961 BUSHIPS forwarded to CNO the results of the study by Maryland SB&DD of the cost and probable speed of four proposed converted ships with different cargo capacities. As of 24 May 1961 a proposal with a capacity of 138,694 barrels, sustained speed of 16.02 knots, and measurements of 609' length oa, 581' pp x 75' molded beam x 33.9' operating draft, and 30,750 tons at operating draft was preferred, but on 25 May 1961 a proposal with a capacity of 155,651 barrels, sustained speed of 15.68 knots, and measurements of 644' oa, 616' pp x 75' x 34.25' and 33,750 tons was substituted on the grounds that the increased cargo capacity was more important than the speed difference of 0.35 knots and the difference in cost. Both options increased the depth of the ship by five feet, resulting in increased freeboard, a dryer operating platform, and increased cargo capacity. Approved characteristics for an Oiler (AO-22 class) conversion, SCB Project No. 224, were promulgated on 31 May 1961 and updated for an Oiler (AO Jumbo) conversion, SCB Project No. 224 (FY 1964), on 1 April 1963 with a final change to the 1961 document on 16 December 1963. (The only notable difference between the FY 1964 and FY 1963 versions was the addition of JP5 and AVGAS hoses to starboard as well as to port.) On 13 June 1961 Maryland SB&DD was requested to proceed with the second phase of its contract, which consisted of preparing sufficient specifications and contract plans for the 644-foot ship for use in bid packages. By 15 November 1961 Navy and OSD plans called for two AO Jumbo conversions in FY 1963, three in FY 1964, and three in FY 1965. The Ship Design Division (Code 410) reported completion of its work on the FY 1963 ships on 9 April 1962 and on the FY 1964 ships on 1 August 1963.

On 21 June 1961 the chief of BUSHIPS, while supporting this modernization program, warned CNO that it was "a stop-gap measure into which we are being forced due to the paucity of oiler new construction in the last decade and the unlikelihood of incorporating the number of oilers required in near future shipbuilding programs. The ships to be obtained through these measures can in no way be compared to new ships; they are old now and have been steamed long and hard; the proposed refurbishing will be a palliative and not a cure for the Fleet's oiler problem."

The newest AO-22 type ships, AO 105-109, were selected for the FY 1963 and 1964 conversions. In these ships the bow, stern, and midship house were separated from the old mid-section and attached to a new 394-foot one that increased the ships' length by 91 feet. Other improvements included a new large counterbalanced rudder, new shorter propeller shafts, and updated fueling and replenishment at sea equipment that used electro hydraulic instead of steam winches. A new auxiliary generator plant consisting of three large diesel generators with a tall exhaust trunk forward of the aft superstructure was installed to power the new winches and pumps during replenishment, and with this load taken off of the steam plant the replenishment speed of the ships rose from about 12-13 to 15-16 knots. The ships had four fueling stations and one sliding block cargo transfer station to port and two fueling stations and one cargo station to starboard. Initially only a helo VERTREP pickup spot forward was fitted, but later in their careers many of these ships had the refueling station ahead of the bridge deleted, clearing more deck space for full helicopter operations. The contracts for the two FY 1963 ships (AO-106 and 109) were awarded on 7 March 1963 to the Lockheed Aircraft Corp. for its subsidiary, the Puget Sound Bridge and Dry Dock Co., Harbor Island, Seattle, Wash., and the contracts for the three FY 1964 ships were awarded on 26 November 1963 to the American Shipbuilding Co., Lorain, Ohio., with preparatory and post-conversion work being done at NSY Boston. The three FY 1965 ships were converted to a different design that added some refrigerated and dry stores and ammunition to the tankers' usual fuel oil and jet and diesel fuel, and these conversions are covered separately here as the AO 51 Jumbo class.

Ship Notes:
AONameMANotes
105MISPILLION2701FY 1964 (conversion). Jumboized at American SB, Lorain, Ohio. New mid-section begun at Lorain 30 Mar 64. Ship placed in commission in reserve at Lorain on 16 April 1965 shortly after arrival. Conversion completed at NSY Boston 1 Jun 1966. Decomm. and to MSC 26 Jul 1974. To NDRF 8 Feb 1990. Withdrawn 5 Jan 2012, arrived at Brownsville 4 Mar 2012 to BU.
106NAVASOTA2702FY 1963 (conversion). Jumboized at the Puget Sound Bridge and Dry Dock Co., Seattle, Wash. New mid-section laid down 27 May 1963 and launched 11 Aug 1963 by the Kawasaki Dockyard Co., Kobe, Japan. Ship departed Long Beach 14 Nov 1963 for NSY Bremerton, then entered Puget Sound Bridge and Drydock Co. (Lockheed), Harbor Island, Seattle for the conversion. Her amidships deckhouse was transferred to the new bow/mid-section by heavy lift crane 9 Jan 1964. Conversion completed 28 Dec 1964. Decomm. and to MSC 13 Aug 1975. Out of service 2 Oct 1991, to NDRF 19 Nov 1991. Withdrawn from NDRF 14 Nov 1995 for delivery to Navy buyer.
107PASSUMPSIC2703FY 1964 (conversion). Jumboized at American SB, Lorain, Ohio. New mid-section begun at Lorain 2 Mar 1964. Ship departed Long Beach 12 Oct 1964 for the Great Lakes with a stop at the Boston Navy Yard for preliminary work. Placed "in commission, in reserve" 26 Nov 1964 at Lorain with a nucleus crew of 4 officers and 28 men. Departed Lorain 22 Nov 1965 with a merchant marine master and civilian crew and arrived at Boston 1 Dec 1965. Conversion completed at NSY Boston 15 Dec 1965. Decomm. and to MSC 24 Jul 1973. At Subic Bay during eruption of Mt. Pinatubo 15 Jun 1991 and underway replenishment gear rendered unusable by corrosive ash. To NDRF 18 Dec 1991 for immediate sale at Yokohama, Japan.
108PAWCATUCK2704FY 1964 (conversion). Jumboized at American SB, Lorain, Ohio. New mid-section begun at Lorain 1 Jun 1964. After preliminary work at Boston, the ship arrived at Lorain on 14 Sep 1965. Conversion completed at NSY Boston 16 Dec 1966. Decomm. and to MSC 15 Jul 1975. To NDRF 19 Sep 1991. Withdrawn 19 Oct 2005, scrapping completed 7 Oct 2006.
109WACCAMAW2705FY 1963 (conversion). Jumboized at the Puget Sound Bridge and Dry Dock Co., Seattle, Wash. New mid-section laid down 10 Jun 1963 and launched 28 Sep 1963 by the Kawasaki Dockyard Co., Kobe, Japan. Ship arrived at Seattle on 21 Feb 1964 and was scheduled to enter the conversion yard on 29 Feb 1964. Conversion completed and ship moved to NSY Puget Sound, Bremerton, Wash., 26 Feb 1965, at which time, her status was changed from "in commission, in reserve" to "in commission, active." Decomm. and to MSC 24 Feb 1975. To NDRF 11 Oct 1989. Withdrawn 11 Oct 2005, scrapping completed 20 Jun 2006.

Page Notes:
Compiled: 1 Apr 2024
© Stephen S. Roberts, 2024
Special sources: NARA: RG 19 Entry P 62 Box 75 (SCB 224)