The third ship to be so named by the Navy, Somerset was laid down on 9 October 1944, under US Maritime Commission (MARCOM) contract, MC hull 2166, by the Leathem D. Smith Shipbuilding Company, Sturgeon Bay, Wisconsin; launched on 21 January 1945; sponsored by Mrs. Fred Bradley, wife of the Michigan congressman.

Transferred again, to the War Department, on 2 August 1946 at Baltimore, Maryland., the ship entered the Reserve Fleet, berthed at Suisun Bay, California, on 28 September 1949, with the US Army retaining her title.

[4] Along with Rose Knot, Coastal Sentry not only collected and relayed radio telemetry information from on board spacecraft, but operated in the command-control role, having embarked National Aeronautics and Space Administration (NASA) flight controllers.

As an example of that work, Coastal Sentry initiated the necessary re-entry command signals on the Gemini VIII mission when the capsule had to make an emergency landing in the Pacific on 17 March 1966.

[6] Transferred to the Maritime Administration (the successor of MARCOM) on 11 July 1968, the ship was delivered the same day to the firm of Fuji Marden and Co., Ltd., of Hong Kong, British Crown Colony, at Fremantle, Australia, for scrapping.