USS San Carlos (AVP-51)

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USS San Carlos (AVP-51).jpg
USS San Carlos (AVP-51) off Houghton, Washington, on 30 March 1944
Career (United States) 100x35px
Name: USS San Carlos (AVP-51)
Namesake: San Carlos Bay, Florida
Builder: Lake Washington Shipyard, Houghton, Washington
Laid down: 17 September 1942
Launched: 20 December 1942
Sponsored by: Mrs. Henry D. Batterton
Commissioned: 21 March 1944
Decommissioned: 30 June 1947
Honors and
Three battle stars for World War II service
Name: USNS Josiah Willard Gibbs (T-AGOR-1)
Namesake: Josiah Willard Gibbs
Builder: Lake Washington Shipyard, Houghton, Washington
Converted in 1958 by Mobile Ship Repair Company, Mobile, Alabama
In service: 18 December 1958 with Military Sea Transportation Service
Out of service: 7 December 1971
Refit: As oceanographic research ship July-December 1958
Struck: 7 December 1971
Fate: Transferred to Hellenic Navy, 15 December 1971
Career (Greece) 100x35px
Name: Hephaistas (A413)
Struck: April 1976
General characteristics as seaplane tender
Class and type: Barnegat-class seaplane tender
Displacement: 1,766 tons (light)
2,750 tons (full load)
Length: 310 ft 9 in (94.72 m)
Beam: 41 ft 2 in (12.55 m)
Draft: 13 ft 6 in (4.11 m)
Installed power: 6,000 hp (4,500 kW)
Propulsion: Diesel engines, two shafts
Speed: 18.6 knots (34.4 km/h)
Complement: 215 (ship's company)
367 (including aviation unit)
Sensors and
processing systems:
Radar; sonar
Aviation facilities: Supplies, spare parts, repairs, and berthing for one seaplane squadron; 80,000 US gallons (300,000 l; 67,000 imp gal) aviation fuel

USS San Carlos (AVP-51) was a Barnegat-class seaplane tender built for the United States Navy during World War II. San Carlos, named after San Carlos Bay, Florida, was in commissioned from 1944 to 1947 and earned three battle stars for service in the Pacific during World War II. After eleven years in reserve, San Carlos was converted to oceanographic research ship USNS Josiah Willard Gibbs (T-AGOR-1)—named after American scientist Josiah Willard Gibbs—and placed in service as a non-commissioned ship of the Military Sea Transportation Service from 1958 to 1971. In December 1971, the ship was transferred to the Hellenic Navy as Hephaistas (A413), a motor torpedo boat tender. Hephaistas was struck from the rolls of the Hellenic Navy in April 1976.

World War II: Seaplane tender

San Carlos was laid down on 17 September 1942 by Lake Washington Shipyard at Houghton, Washington. She was launched on 20 December 1942, sponsored by Mrs. Henry D. Batterton, and commissioned on 21 March 1944 with Lieutenant Commander De Long Mills in command.

After shakedown, San Carlos departed Southern California on 1 June 1944. Arriving at Green Island on 25 June 1944, she engaged in air-sea rescue operations in the northern Solomon Islands from 26 June 1944 to 3 September 1944, and at Morotai Island, shortly after its capture from the Japanese, from 18 September 1944 to 30 September 1944.

Arriving off Leyte in the Philippine Islands on 18 October 1944 at the beginning of the Philippines campaign, San Carlos fueled battleship and cruiser observation floatplanes. She shot down one Japanese plane on 21 October 1944. Arriving at San Pedro Bay, Leyte, on 24 October 1944, she tended seaplanes there and downed another Japanese plane on 27 October 1944.

Departing on 4 November 1944, she made a cargo trip to Humboldt Bay, New Guinea, returning to San Pedro Bay on 18 November 1944. Arriving at San Juanico Strait on 22 November 1944, she shot down another Japanese plane on 26 November 1944 and tended seaplanes there until 22 January 1945. After duty at Mindoro Island in February 1945, she tended seaplanes near Cavite, on Luzon, from March 1945 until 11 August 1945.

San Carlos arrived at Bremerton, Washington, on 3 September 1945. After overhaul there, she operated out of Coco Solo, Panama Canal Zone, from December 1945 through May 1946, and out of San Juan, Puerto Rico, from July 1946 to March 1947. Decommissioned on 30 June 1947 at the Philadelphia Navy Yard at Philadelphia, Pennsylvania, San Carlos was laid up in the Atlantic Reserve Fleet. San Carlos received three battle stars for her World War II service.

Oceanographic research ship

After eleven years of inactivity, San Carlos was taken out of reserve on 11 July 1958 and assigned to the U.S. Navy's Military Sea Transportation Service for conversion to an oceanographic research ship by Mobile Ship Repair Company of Mobile, Alabama. Alterations to her original design included the installation of six laboratories, a machine shop, a darkroom, a superstructure deck locker for experimental stowage or work, and a deep-sea winch capable of handling up to 40,000 feet (12,000 m) of wire rope and 20 long tons (20 t) of equipment. In her modified form, she required a crew of 48 and could accommodate a scientific staff of 24.

On 15 December 1958, the ship was renamed USNS Josiah Willard Gibbs, in honor of American scientist Josiah Willard Gibbs and re-designated as T-AGOR-1, an oceanographic research ship. On 18 December 1958, she was placed in non-commissioned service as a United States Naval Ship under control of the Military Sea Transportation Service.

Josiah Willard Gibbs became the principal research vessel of the Hudson Laboratories of Columbia University, under contract to the Office of Naval Research. For thirteen years she provided transportation, accommodations, and working spaces for American scientists and technicians investigating physical, chemical, and biological properties of the ocean. She was dedicated primarily to research in the physics of the ocean, particularly the propagation of sound, as part of efforts by the Office of Naval Research to improve the U.S. Navy's submarine and anti-submarine warfare capabilities. Her relatively large size allowed her to handle heavier weights at greater depths and provide greater stability for delicate scientific measurements than any other oceanographic research vessel then in use. Her large deep-sea winch and auxiliary propeller gave her the capability to investigate even the deep ocean trenches scattered throughout the world.

Josiah Willard Gibbs was taken out of service on 7 December 1971 and stricken from the Naval Vessel Register the same day.

Hellenic Navy career

Josiah Willard Gibbs was transferred to the Greek Navy on 15 December 1971. She then became the Greek motor torpedo boat tender[1] Hephaistas (A413). She was stricken by the Greek Navy in April 1976.


  1. The Dictionary of American Naval Fighting Ships (DANFS) entry for USS San Carlos (AVP-51) (see claims USNS Josiah Willard Gibbs became an oceanographic research ship in Greek Navy service, but the Naval Historical Center's Online Library of Selected Images entry for USNS Josiah Willard Gibbs (see, which updates the DANFS entry, says that the ship was a motor torpedo boat tender in Greek service.