28 Professional BoatBuilderHIGH SPEED: Foiling, Part 1only six of these formidable high-tech
vessels. They were 133' (40.5m), car-
ried a crew of four officers and 17
enlisted sailors, and were armed with
eight Harpoon surface-to-surface-
missile launchers and an automatic
76mm gun. They had two waterjet pro-
pulsion systems: one for hullborne
operation at speeds up to 11 knots, con-
sisting of two MTU diesels with 1,600
brake horsepower; and another for
foiling, powered by a General Electric
LM-2500 gas turbine engine with
18,000 shaft horsepower.
“The foilborne control systems
were adapted from airplanes and
used radar sensors to control the
ship’s flying height,” explained Mark
Bebar, a naval architect employed by
the Naval Ship Engineering Center
(NAVSEC) who worked on the PHM
program in the 1970s. “These ships
were capable of operating in 10' [3m]
waves at a foilborne speed of 48
knots with root mean square vertical
accelerations [RMSVA] of less than
0.25 g in the wheelhouse, which was
required by the ship specifications,”
Bebar said.In the early 1970s, Boeing received
the order to develop fast attack patrol
boats of the Pegasus Class (also called
PHM for Patrol Hydrofoil Missile) for
operation in coastal waters and to
counter Soviet and Warsaw Pact mis-
sile boats. But funding became prob-
lematic as the navies of other NATO
countries opted out, so Boeing builtretractable foils. Foilborne operation
relied on propulsion nacelles with four
propellers on the aft struts, while a
steerable outdrive was used in dis-
placement mode. The advantages of
this system included higher efficiency
and better seakeeping in rough weather,
but the system needed sophisticated
controls to operate the vessel safely
and effectively.
Still, the Navy envisioned
hydrofoiling ships as part of
its Cold War arsenal, award-
ing two contracts for hydro-
foiling gunboats. Grumman
delivered its USS Flagstaff
(PGH-1), with an airplane
foil arrangement, while
Boeing chose a canard foil
arrangement and waterjet
propulsion for the USS
Tucumcari (PGH-2). Also
in 1965, Lockheed went
really big with the 320-ton
USS Plainview (AEGH-1).William P. Carl conceived fast planes and vessels. In the 1950s, the designer of the
P-38 Lightning aircraft followed Bell’s and Baldwin’s lead, putting two aircraft engines
on the experimental XCH-4 (aka the Carl Boat), shown here on an ocean test run.The USS High Point patrol
vessel with retractable foils
in canard configuration was
launched in 1962. Note
the different propulsion
systems for foiling and
hullborne operation.Wikimedia commonsU.s. n
avy
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