The Kennebec-class oilers were sixteen United States Navy medium oilers (replenishment tankers) 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. One is still in commercial service as of 2026.

All of the ships of the class initially were to be built for private companies, but at the outset of World War II, the ships were transferred to the United States Maritime Commission and given new names. Later, when allocated to the U.S. Navy, they were renamed again.

In some cases the Kennebec class is divided into three classes, the Kennebec class (AO-36 to AO-40, AO-48), the Mattaponi class (AO-41 to AO-44, AO-47) and the class (AO-68 to 72). The first two classes were of the T2 and T2-A designs, built by different shipbuilders, and the Chiwawas were of the T3-S-A1 design, mainly differing in having only a engine and a top speed of .

History One of the first acts of the War Shipping Administration (WSA), established in February 1942, was to address the Navy's pressing need for oilers by requisitioning five tankers in service or under construction for civilian companies. Three of these were Type T2 "national defense tankers" designed by the Maritime Commission with potential militarization in mind and built by Bethlehem Steel for Socony-Vacuum Oil Co: the Corsicana, Caddo and Calusa. A month later the WSA requisitioned six more: Socony's Colina and Conastoga, together with four similar ships building at Sun Shipbuilding and Drydock for Keystone Tankships to an enlarged design, later called T2-A: Kalkay, Ellkay, Jorkay and Emkay. Corsicana was commissioned as USS Kennebec, becoming the lead ship of the class; Kalkay was renamed Mattaponi and gave that name to the T2-A subclass. In June the WSA moved to acquire the remaining member of each group, Aekay and Catawba.

The T2 design had itself been based on two ships built by Bethlehem Steel in 1938–39, Mobilfuel and Mobilube; the T2's principal difference was MarCom's inclusion of more powerful engines to produce the Navy's desired 16.5 knots. In the meantime MarCom under the State of Emergency had ordered thirteen duplicates of Mobilfuel for the merchant marine; the first of these were nearing completion in late 1942 when the Navy, still very short of oilers, requisitioned the first five starting with Samoset (ex-Mobiloil), renamed USS Chiwawa. Other than being limited to 15 knots, the Chiwawas were effectively identical to the Kennebecs, despite being assigned the confusing design code T3-S-A1.

All sixteen ships survived the war, but were decommissioned shortly afterwards in favor of the larger, faster . Kennebec, Merrimack, Kankakee, Mattaponi, Monongahela, Tappahannock, and Neches were recommissioned for the U.S. Navy after World War II. Mattaponi and Tappahanock were reactivated four times, serving until 1970.

Chiwawa (now Lee A. Tregurtha) is still in commercial service on the Great Lakes. Neshanic (now American Victory) was sold for scrap and towed away to Turkey in 2018.

Ships of the class + Construction data Name Original name Commissioned Final decommission Fate AO-36 Corsicana 4 Feb 1942 1 Apr 1970 scrapped, 1982 AO-37 Caddo 4 Feb 1942 29 Nov 1957 scrapped, 1982 AO-38 Calusa 27 Jan 1942 30 Apr 1946 sold commercial 1947, scrapped 1965 AO-39 Colina 4 May 1942 27 Jun 1968 scrapped, 1976 AO-40 Conastoga 10 Ju 1942 14 Feb 1946 sold commercial 1947, scrapped 1967 AO-48 Catawba 16 Sep 1942 13 Dec 1945 sold commercial 1947, scrapped 1964

+ Construction data for Mattaponi subclass Name Original name Commissioned Final decommission Fate AO-41 Kalkay 10 May 1942 30 Sep 1970 scrapped, 1973 AO-42 Ellkay 11 Sep 1942 22 Aug 1957 scrapped, 1982 AO-43 Jorkay 22 Jun 1942 6 Mar 1970 scrapped, 1987 AO-44 Emmkay 22 Oct 1942 21 Feb 1946 sold commercial 1947, scrapped 1985 AO-47 Aekay 16 Sep 1942 1 Oct 1970 scrapped, 1973

+ Construction data for Chiwawa subclass Name Original name Commissioned Final decommission Fate AO-68 Samoset, ex-Mobiloil 24 Dec 1942 6 May 1946 converted to Great Lakes ore carrier, 1961; still in service AO-69 Sachem 23 Jan 1943 22 Oct 1957 scrapped, 1982 AO-70 Shabonee 30 Jan 1943 12 Dec 1945 sold commercial 1947, sunk 1960 AO-71 Marquette 13 Mar 1943 19 Dec 1945 converted to laker; sold for scrap 2018 AO-72 Citadel 20 Feb 1943 12 Nov 1957 scrapped 1982

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