Warships on Skis
Bloom, Jim, Sea Classics
Unique hydrofoils gave the Navy a fast, multi-purpose gunboat that, for a time, intrigued planners with their versatility
In a previous article on the US Navy's experience with the lowly "patrol gunboat" ("Armed & Alone: America's Century-Long Romance with Gunboats," Sea Classics, December, 2007), I remarked how the US Navy habitually neglected its patrol craft and gunboat vessels in favor of the major Naval combatants, once called "capital ships." This is largely due to Adm. Alfred Mahan's hold on Naval thinking. Mahan's 1890s treatises featured decisive fleet-to-fleet engagements on the high seas employing armored cruisers and battleships. Lesser craft were regarded as suitable for little else than secondary, shoreline policing tasks. The Naval strategy guru did not foresee the eventual effectiveness of the little "Davids" - armed with the Whitehead torpedo - in bringing down his favored capital ship "Goliathe".
The lapses from this institutional indifference have been sporadic and short-lived. The problem is that the Navy is run by blue-water so anything that isn't a long-haul, heavy-weapons platform destined for carrier battle group support on the high seas is an oddity. The lessons regarding the value of the small vessels that were occasionally employed were habitually misread or overlooked and the craft were abandoned while preparing for the Next Great Naval War. So we now have the "littoral warfare" model, in which patrol craft excel, and instead find ourselves with an expensive new "littoral warfare ship" that borders on the size and price of a frigate. This shortsightedness is nowhere better summarized than in the brief career of the PHMs.
The evolution, operational record and decline of the Patrol Hydrofoil, Missile (PHM) program from the mid-1970s to the final de-commissioning of the six PHMs of the Pegasus-class in 1993, underscores the Navy's myopic attitude towards the patrol boat in general and the dismal prospects for the future of such craft in US Navy doctrine. To some extent, the PHM's acceptance troubles replicated those of the earlier Patrol Gunboata of the j4sheviiie-class, direct descendants of the World War II-era PT boats. Although this article focuses on the PHM, it illustrates the blinkered vision of the world's Big Power Navies towards creating a proficient patrol force tailored towards dealing with burgeoning threats below the capital ship encounter threshold.
Before getting into the NATO project that eventually resulted in the PHMs, we should understand the history of hydrofoil boats, and in particular their military applications. For anyone unfamiliar with the hydrofoil principle, the idea is to utilize an airfoil-type assembly that can be deployed on retractable struts that extend beneath the vessel's hull. When the vessel reaches a certain speed, the foils will be swung underneath the vessel and lift the hull clear of the water, much in the same manner that a rapidly moving wing on an aircraft will cavitate, providing lift to the plane. Thus, hydrofoils replicate the airplane wing cross-section, using the strut-mounted "wings" that project just beneath the water's surface when activated. At a certain - generally high - speed, the unequal pressure above and below the hydrofoil will raise the ship's hull clear of the water, similarly to the atmospheric effect on the aircraft wing, and thus allow the flat lifting blades and struts, which generate little water resistance, to achieve relatively high speeds. Also, foilborne operation enables the ship to continue its mission in turbulent sea conditions since the action of waves and currents against the slim foil-andbrace structure is negligible compared to that which would be experienced by the fully immersed hull.
Although the US Navy's early and mid-1960s experiments were the harbingers of the refined hydrofoil fast-attack missile boat, in fact, hydrofoil-assisted maritime craft had been around since the beginning of the 20th century, a prominent pioneer being Alexander Graham Bell, the inventor of the telephone. …