USS Flagstaff (PGH-1) was the only Flagstaff-class patrol gunboat (hydrofoil) and was acquired by the United States Navy because of her relatively low cost and very high speed.

There was also considerable interest in developing new "high-speed ways" to combat narcotics smuggling by sea, conduct search and rescue operations, fisheries enforcement, and marine environmental protection.

Flagstaff was developed by the Navy as an experimental vessel under project SCB 252[1] and was built by Grumman Aerospace Corporation of Bethpage, New York.

[citation needed] Flagstaff and Tucumcari were too mechanically complex for the repair facilities in Vietnam, and as a result were ultimately withdrawn from combat.

[2] Upon her return to the U.S. in 1970, she was assigned to the Amphibious Forces of the Pacific Fleet where she participated in numerous readiness trials and training exercises and was also used as a test-bed for various craft subsystems, such as the Navy's Advanced Hydrofoil Development Program.

In one hour, the ship was on scene and quickly located a family of three who had jumped into the water to escape the flash fire that had engulfed the cabin of their 40 ft (12 m) boat.

Ultimately, the evaluation demonstrated that she showed promise in both anti-smuggling operations and as a rapid response search and rescue vessel.

The Coast Guard once again acquired Flagstaff from the Navy on 29 September 1976 in San Diego, California, for further evaluation "in a fully operational environment".

She was transported to the U.S. East Coast for testing in the "adverse weather conditions" that prevailed in the waters off the New England in the hope of having her conduct actual operational missions.

The emphasis for this evaluation was to test her capabilities to enforce the new 200 mi (320 km) fisheries economic zone, in addition to the traditional Coast Guard missions.

The Coast Guard decided to decommission her due to "the high cost of repairs and the fact that the CG feels sufficient information has been gained from the E.P.

The escalating costs of repair, and the fact that she needed an engine replacement too, figured into the decision to return her to the Navy.