Between 1941 and 1946, the United States Navy acquired 35 Barnegat-class small seaplane tenders, designated "AVP" in the Navy's alphanumeric hull numbering system and designed to logistically and administratively support a squadron of flying boats operating from undeveloped areas and, with a substantial anti-air, antisurface, and antisubmarine capability, to escort larger seaplane tenders.

Most of them served during World War II, although even during the war the Navy determined the number of Barnegats to be surplus to requirements; as a result, one was completed as a catapult training ship for Navy floatplane pilots (retaining its "AVP" designation) and four were converted during construction into motor torpedo boat tenders, redesignated "AGP".

[2] After World War II, the Navy had a surplus of seaplane tenders, and the Coast Guard was looking for ships to serve on ocean stations in the Atlantic and Pacific Oceans on weather-reporting duties, also performing law enforcement and search and rescue operations as required.

The Barnegats were reliable, long-ranged, and seaworthy, and had good habitability,[3] and, suitably modified, were good candidates to meet the Coast Guard's requirements; in the words of the Coast Guard's assessment of the Barnegats, "The workmanship on the vessel is generally quite superior to that observed on other vessels constructed during the war.

The vessel has ample space for stores, living accommodations, ships, offices and recreational facilities.

"[4] The Navy transferred three of the seaplane tenders outright to the Coast Guard in 1946; they entered service that year and in 1947.

Of the ships the Coast Guard received, two had been built by the Boston Navy Yard at Boston, Massachusetts, and the rest in the state of Washington: three by Associated Shipbuilders, Inc., at Seattle, ten by Lake Washington Shipyard at Houghton, and three by the Puget Sound Navy Yard at Bremerton.

Once they were accepted into Coast Guard service, a number of changes were made to prepare the ships for ocean-station duty.

The former seaplane tenders and the former catapult training ship thus all received the classification "WAVP"; the two former motor torpedo boat tenders (AGPs), which reverted to their original "AVP" designation before transfer to the Coast Guard, also entered Coast Guard service as WAVPs.

In 1966 the Coast Guard reclassified all of the Cascos—including Rockaway—as high endurance cutters and changed their classification to "WHEC".

Unimak was a training ship (WTR-379) from 1969 to 1975 before reverting to her WHEC classification, Gresham became a "meteorological cutter" (WAGW-387) in 1970, and Rockaway became an "offshore law enforcement vessel" (WOLE-377) in 1971.

The class was named for USCGC Casco (WAVP-370), later WHEC-370, the unit with the lowest Coast Guard alphanumeric hull number.

The last survivor in Coast Guard service, Unimak, was scuttled to form an artificial reef.

The seventh ship, RVNS Pham Ngu Lao, the former Absecon, was captured by North Vietnam, appears to have remained active in the Vietnam People's Navy into the 1990s, and may remain afloat today as the last surviving Barnegat- or Casco-class ship.

Her current status is unclear, although she may remain afloat as the last surviving Barnegat- or Casco-class ship.

Upon the collapse of South Vietnam in 1975, she fled to the Philippines, where she served as the frigate BRP Andrés Bonifacio (PF-7) until 1985.

Redesignated WHEC-377 and permanently transferred to the Coast Guard in 1966, she was again reclassified as a "offshore law-enforcement vessel," WOLE-377, in 1971.

Recommissioned in 1977 and again designated WHEC-379, she was stationed at New Bedford, Massachusetts, for the remainder of her Coast Guard career, focusing primarily on fisheries patrols in the Atlantic and law enforcement operations in the Caribbean.

Upon the collapse of the South Vietnamese government at the end of the Vietnam War in 1975, she fled to the Philippines, where she was cannibalized for spare parts.

She was based at Portland, Maine, from 1949 to 1968, primarily responsible for ocean station patrols in the North Atlantic.

In 1966 she was reclassified as a high endurance cutter, redesignated WHEC-381, and transferred outright to the Coast Guard.

She was based at San Francisco, California, from 1968 to 1969, where she carried out for law-enforcement and search-and-rescue duties in the Pacific.

Based at Portland, Maine, throughout her Coast Guard career, she was primarily responsible for ocean station patrols in the North Atlantic and spent one combat tour in Vietnam during the Vietnam War with Coast Guard Squadron Three in 1971.

Upon the collapse of the South Vietnamese government at the end of the Vietnam War in 1975, she fled to the Philippines, where she was cannibalized for spare parts.

Based at Boston, Massachusetts, from 1946 to 1952. she primarily was responsible for ocean station patrols in the North Atlantic.

Gresham served as the U.S. Navy motor torpedo boat tender USS Willoughby (AGP-9) from 1944 to 1946.

She was based at Norfolk, Virginia, from 1970 to 1973, responsible for ocean station patrols in the North Atlantic, and was reclassified as a meteorological cutter and redesignated WAGW-387 in 1970.