USS Half Moon, a 1,766-ton Barnegat class small seaplane tender, was built at Houghton, Washington, and was commissioned in June 1943. She had been selected in March 1943 for conversion to a PT-boat tender, AGP-6, but Oyster Bay (AVP-28) was substituted in May because Half Moon was nearly complete as an AVP. Half Moon departed San Diego in late August 1943 for the Southwest Pacific, and between October and December she tended seaplanes at Namoai Bay on Sariba Island, New Guinea. She remained in the New Guinea theater until October 1944, tending seaplanes at Finshafen, Middleburg and Morotai as well as providing transport services within the theater.

In October 1944 Half Moon departed Morotai for the Philippines, where she established a seaplane base on the eastern coast of Leyte Island in support of invasion operations there. She witnessed the Battle of Surigao Strait, and continued to support seaplane operations in the Philippines through August 1945. She survived a typhoon while in transit to Okinawa in early September, returned to the Philippines in October, and departed for Seattle and deactivation in November. Half Moon was decommissioned at San Diego in September 1946.

In September 1948 Half Moon was loaned to the Coast Guard as the cutter Half Moon (WAVP-378, later WHEC-378). She served out of the New York City area, primarily on weather station duty. She was decommissioned in July 1969 and sold for scrap in May 1970.