USS Humboldt (AG-121)

antiaircraft gun mounts.
Career (USA)
Name: USS Humboldt
Namesake: Humboldt Bay, on the northern coast of California, some 250 miles (400 km) north of San Francisco, California
Builder: Boston Navy Yard, Boston, Massachusetts
Laid down: 6 September 1940
Launched: 17 March 1941
Sponsored by: Mrs. William T. Tarrant
Commissioned: 7 October 1941
Decommissioned: 17 March 1947
Reclassified: Miscellaneous auxiliary (as press information ship), AG-121, 30 July 1945
Returned to seaplane tender designation, AVP-21, in 1945 after conversion to AG-121 cancelled
Struck: 1970
Fate: Loaned to U.S. Coast Guard, 24 January 1949
Transferred permanently to Coast Guard 26 September 1966
Transferred to U.S. Navy 30 September 1969
Sold for scrapping May 1970
Notes: Served as U.S. Coast Guard cutter USCGC Humboldt (WAVP-372), later WHEC-372, 1949–1969
General characteristics
Type: Barnegat-class small seaplane tender
Displacement: 1,766 tons (light)
2,750 tons (full load)
Length: 311 ft 8 in (95.00 m)
Beam: 41 ft 1 in (12.52 m)
Draft: 13 ft 6 in (4.11 m)
Installed power: 6,000 horsepower (4.48 megawatts)
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
Armament: 2 x single 5-inch (127 mm) 38-caliber dual-purpose gun mount
4 x dual 20-mm antiaircraft gun mounts
2 × depth charge tracks
Aviation facilities: Supplies, spare parts, repairs, and berthing for one seaplane squadron; 80,000 US gallons (300,000 L) aviation fuel

USS Humboldt (AVP-21) was a United States Navy Barnegat-class small seaplane tender in commission from 1941 to 1947. She was briefly reclassified as a miscellaneous auxiliary and redesignated AG-121 during 1945.

Construction and commissioning

Humboldt (AVP-21) was laid down at the Boston Navy Yard in Boston, Massachusetts, on 6 September 1940. She was launched on 17 March 1941, sponsored by Mrs. William T. Tarrant, and commissioned on 7 October 1941 with Commander W. G. Tomkinson in command.

World War II service

South Atlantic operations

Following rigorous shakedown training off the United States East Coast, Humboldt sailed from Norfolk, Virginia, on 13 May 1942 to join Rear Admiral Jonas H. Ingrain's South Atlantic Force on the coast of Brazil. After stops at San Juan, Puerto Rico, and Trinidad, she arrived at Recife, Brazil, on 5 August 1942 and began tending the seaplanes of Patrol Squadron 83 (VP-83).

During the months that followed, these patrol aircraft, operating with ships of the Brazilian Navy and U.S. Navy, patrolled the South Atlantic Ocean sea lanes and hunted Axis submarines. Humboldt supplied and repaired seaplanes and, in addition, carried aviation gasoline to outlying air bases along the Brazilian coast while engaging in antisubmarine patrols herself.

President Roosevelt arrives on board

While at Natal, Brazil, on 28 January 1943, Humboldt was the site of a conference between President Franklin D. Roosevelt, who was returning from the Casablanca Conference, and President Getúlio Vargas of Brazil. This meeting helped to achieve even closer cooperation between the naval units of the two countries.

Continued South Atlantic operations

After the meeting of the two presidents, Humboldt continued to visit isolated ports on the Brazilian coast with supplies and established a new seaplane base at Aratú, Bahia, Brazil, in May 1943.

North Atlantic operations

Humboldt headed north on 1 July 1943, arriving at Boston, Massachusetts, on 17 July 1943 to take up new duties in the North Atlantic Ocean. Departing on 23 August 1943, she carried supplies and parts to U.S. Navy fleet air wings in Newfoundland, Iceland, and the United Kingdom. She continued this dangerous duty, often sailing unescorted, into the early months of 1944, occasionally sailing to Casablanca, French Morocco as well.

Humboldt was at Casablanca in late May 1944 when she heard that a German submarine had torpedoed escort aircraft carrier USS Block Island (CVE-21) and destroyer escort USS Barr (DE-576) in the Atlantic, sinking Block Island and damaging Barr. Humboldt steamed out to help with survivors and to escort Barr to safety.

Humboldt was soon underway again, this time to bring an experienced U.S. Navy submarine officer to rendezvous with escort aircraft carrier USS Guadalcanal (CVE-60) hunter-killer group, which had just captured the U-505 in an epic encounter on 4 June 1944.

Humboldt continued to bring supplies to aviation squadrons in the Azores and North Africa until 22 March 1945.

Return to South Atlantic service

On 22 March 1945, Humboldt departed Norfolk, Virginia, for Brazil. Returning to her original seaplane tending duties in the South Atlantic, Humboldt arrived at Recife, Brazil, on 5 April 1945 and remained on duty until the surrender of Germany in early May 1945, after which she departed Brazil for Norfolk on 10 June 1945.

Conversion to press information ship

Humboldt moved to the Philadelphia Navy Yard in Philadelphia, Pennsylvania, on 16 July 1945, for conversion to a press information ship. Reclassified as a miscellaneous auxiliary and redesignated AG-121 on 30 July 1945, Humboldt was to serve as a broadcast and teletype center for correspondents during the planned invasion of Japan in 1945–1946. However, hostilities with Japan ended on 15 August 1945, making the invasion unnecessary before her conversion was completed.

Post-World War II decommissioning

Humboldt was converted back into a seaplane tender and was again designated AVP-21. She arrived at Orange, Texas, on 22 November 1945, for inactivation. She was decommissioned on 19 March 1947 and laid up in the Atlantic Reserve Fleet at Orange.

United States Coast Guard service

Loaned to the United States Coast Guard on 24 January 1949, Humboldt was commissioned as the cutter USCGC Humboldt (WAVP-372) on 29 March 1949. Based at Boston, Massachusetts, and reclassified as a high endurance cutter and redesignated 'WHEC-372 on 1 May 1966, her primary duty was to patrol ocean stations in the North Atlantic, providing weather reporting services and engaging in search-and-rescue and law-enforcement operations. She was transferred permanently to the Coast Guard on 26 September 1966.

Final disposition

On 30 September 1969, the Coast Guard decommissioned her and transferred her to the U.S. Navy. Stricken from the Navy List in 1970, she was sold for scrapping in May 1970 and scrapped in Italy.


  • This article incorporates text from the here.
  • (AVP-21), 1941-1949
  • NavSource Online: Service Ship Photo Archive - USS Humboldt (AVP-21) (AG-121) - USCGC Humboldt (WAVP-372) (WHEC-372)
  • s Office: Humboldt, 1949 WHEC-372 Radio call sign: NEJL
  • Chesneau, Roger. Conway's All the World's Fighting Ships 1922–1946. New York: Mayflower Books, Inc., 1980. ISBN 0-8317-0303-2.
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