Hydrofoils: Ships That Fly

By: Megan Churchwell, Curator, Puget Sound Navy Museum

The U.S. Navy’s fleet of big ships is balanced by a diverse collection of smaller vessels including speedy patrol boats. Of these, hydrofoil patrol boats were some of the most unusual vessels of the U.S. Navy fleet. And now, thanks to the Puget Sound Navy Museum’s newest exhibit, “Patrol Boats on Puget Sound,” visitors can see first-hand hydrofoils and other small, fast patrol boats that have operated on Puget Sound for more than a century!

These vessels would “fly” above the sea, with water flowing over submerged foils like air flowing over airplane wings. The hydrofoil depended on forward speed to generate lift on its underwater wings, much like an airplane flying through the air.

USS Pegasus - from NHHC L-File

Hydrofoil patrol boats had several advantages over traditional hulls:

  • The underwater wings lifted the hull out of the water, reducing drag
  • Hydrofoil boats’ small submerged area reduced risk of torpedo attacks
  • The underwater wings increased stability, enabling hydrofoils to maneuver in rough water

Test Designs

Starting in the 1950s, Boeing began applying its aircraft design expertise to hydrofoil boats. Early Boeing hydrofoil research resulted in the launching of three test designs: Aqua-Jet (1959), Little Squirt (1962) and FRESH-1 (1963). Measuring between 20 and 53 feet long, they were tested at speeds approaching 100 miles per hour, greatly adding to the era’s knowledge of how high speed hydrofoils work. The Puget Sound Naval Shipyard, owing to its proximity to Boeing’s facilities, became a hotbed of hydrofoil testing.

USS High Point (PCH-1) “Flying” above the surface of Puget Sound, the United States Navy’s first patrol craft – hydrofoil

USS High Point (PCH 1)

USS High Point (PCH 1), the U.S. Navy’s first operational hydrofoil, was launched in 1962. Operating from the Puget Sound Naval Shipyard, she underwent testing at speeds of more than 50 knots.

It was hoped that hydrofoils like High Point would join the fleet as antisubmarine warfare vessels. However, testing revealed that the hydrofoil technology was not yet advanced enough to produce a reliable hydrofoil to join the fleet, and more research was needed. Still, much was learned through these tests. In 1975, High Point was transferred to the U.S. Coast Guard for evaluation as a coastal patrol vessel.

USS Plainview (AGEH 1)

USS Plainview (AGEH 1) was built by Lockheed Shipbuilding and Construction Company and operated out of the Puget Sound Navy Shipyard from her 1969 commissioning until 1978. At 220’, she was the world’s largest military hydrofoil. She tested the feasibility of large hydrofoil craft operations at sea. Plainview was used to show the effectiveness of hydrofoils in accomplishing Navy missions like launching torpedoes, firing missiles, and underway replenishment.

USS Plainview reminded many crew members of an airplane, with her aluminum construction and Lockheed jet aircraft engines. Her bridge was often compared to an airplane cockpit because of the many dials and gauges.

USS Tucumcari (PGH 2), the first weapon-equipped military hydrofoil

USS Tucumcari (PGH 2), the first weapon-equipped military hydrofoil

USS Tucumcari (PGH 2)

USS Tucumcari (PGH 2), designed by Boeing, was the first weapon-equipped military hydrofoil. The heavily-armed “TUC” was launched in 1967. She measured 71’ long, and carried a 40mm cannon, four .50 caliber machine guns, and an 81mm mortar.

Early Boeing hydrofoil test pilot Vern Salisbury, who had been a Marine fighter pilot during the Korean War, said that hydrofoils offered more thrills than flying. On testing runs aboard USS Tucumcari, he ran rings around Coast Guard patrol boats and even circled nuclear submarines. “Heads would pop out of the hatches as we would circle,” he recalled. At the time, the top speed (more than 50 knots per hour) was considered classified.

Following extensive tests in Washington and California, Tucumcari was sent to Vietnam, becoming the first U.S. Navy hydrofoil to see combat duty.

USS Pegasus and the Navy’s PHM Program

After the success of USS Tucumcari, the Navy asked Boeing to produce a larger armed hydrofoil. The PHM (Patrol Hydrofoil Missile) program consisted of six hydrofoil patrol boats. At 132 feet, they were nearly twice as long as Tucumcari. Heavily armed for their size, with a 76mm rapid-fire gun and eight Harpoon missiles, PHM boats could challenge much larger warships.

Launched by Boeing between 1974 and 1982, all six Pegasus-class hydrofoils were assigned to patrol the waters around Key West, Florida to combat drug trafficking. With speeds in excess of 40 knots in any weather, they were the only U.S. ships that could outrun the speedy boats used by smugglers.

The End of an Era

In 1993, the PHMs were decommissioned due to government cutbacks. However, the technology developed by the PHM program contributed to the creation of several types of commercial hydrofoils, such as the Boeing Jetfoil passenger ferries launched in the 1980s.

The Puget Sound Navy Museum’s newest exhibit, “Patrol Boats on Puget Sound,” features hydrofoils and other small, fast patrol boats that have operated on Puget Sound for more than a century. “Patrol Boats on Puget Sound” opened on March 3, 2017 and will remain on view for two years.

Check out the 1975 Navy documentary video on the hydrofoil technology of the USS Pegasus (PHM-1)