Hydrofoil
A
hydrofoil is a
boat with wing-like
foils mounted on struts below the
hull. As the craft increases its speed the hydrofoils develop enough
lift for the boat to become foilborne - i.e. to raise the hull up and out of the water. This results in a great reduction in
drag and a corresponding increase in speed.
Early hydrofoils used U-shape foils. Hydrofoils of this type are known as
surface-piercing since portions of the U-shape hydrofoils will rise above the water surface when foilborne. Modern hydrofoils use T-shape foils which are
fully-submerged. Fully submerged hydrofoils are less subjected to the effects of waves, they are therefore more stable at sea and are more comfortable for the crew and passengers. This type of configuration however is not self-stabilizing. The angle of attack on the hydrofoils needs to be adjusted continuously in accordance to the changing conditions, a control process that is performed by computers. Failure to make the proper adjustments will result in the foilborne hull dropping violently back into the sea.
The term "hydrofoil" is also used to refer to the foil itself, especially when the
airfoil profile has been specifically designed for use in water (such as for a
propeller blade).
A March
1906 Scientific American article by American hydrofoil pioneer William E. Meacham explained the basic principle of hydrofoils.
Alexander Graham Bell considered the invention of the
hydroplane a very significant achievement. After reading this article Bell began to sketch concepts of what is now called a hydrofoil boat. With
Casey Baldwin, he began hydrofoil experimentation in the summer of
1908. Baldwin studied the work of the Italian inventor
Enrico Forlanini and began testing models based on his designs. This led him and Bell to the development of hydrofoil watercraft. During Bell's world tour of 1910-1911 he and Baldwin met with Forlanini in Italy. They had rides in the Forlanini hydrofoil boat over
Lake Maggiore. Baldwin described it as being as smooth as flying. On returning to
Baddeck a number of designs were tried culminating in the HD-4. Using
Renault engines a top speed of 87 km/h (54 mph) was achieved, accelerating rapidly, taking wave without difficulty, steering well and showing good stability. Bell's report to the United States Navy permitted him to obtain two 260 kW (350 horsepower) engines. On
September 9,
1919 the HD-4 set a world marine speed record of 114 km/h (70.86 mph). This record stood for ten years.
Between 1873 and 1914, the British boat designer
John I Thornycroft worked on a series of models with a stepped hull and single bow foil. In 1909 his company built a full scale 22 foot long boat,
Miranda III, driven by 60 hp engine that rode on a bowfoil and flat stern. The subsequent
Miranda IV was credited with 35 knots. [
1].
Baron von Schertel worked on hydrofoils prior to and during
World War II in
Germany. After the war Schertel's team was captured by the Russians. Schertel himself went to
Switzerland, where he established the Supramar company. In
1952, Supramar launched the first commercial hydrofoil, PT10, in Lake Maggiore, between Switzerland and
Italy. The PT10 is of surface-piercing type, it can carry 32 passengers and travel at 35 knots. The Financier Hussain Najadi in 1968 acquired from UBS Group the SUPRAMAR AG of Lucerne, Switzerland. THE COMPANY was the world inventor of Hydrofoils with licensees spanning Europe, USA and Asia. He expanded its operations into Japan, Hong Kong, Singapore, UK, Norway and USA. General Dynamics of the United States became its Licensee and the PENTAGON awarded its first R&D naval research project in the field of super cavitations. Hitachi Shipbuilding of Osaka, Japan, was another Licensee of SUPRAMAR, as well as many leading ship owners and shipyards in the OECD countries. He established over 200 hydrofoil lines spanning five continents.From
1952 to
1971, Supramar designed many models of hydrofoils: PT20, PT50, PT75, PT100 and PT150. Except the PT150, all are of surface-piercing type. Over 200 of Supramar's design were built, most of them by Rodriquez in Italy. Hitachi in Japan had also built some under license.
 |
USS Aquila, a military hydrofoil. The T-shaped foils are visible just below the water. |
The
Canadian Navy built and tested a high-speed anti-submarine hydrofoil, the
HMCS Bras d'Or, in the late 1960s, but the program was cancelled due to a shift away from
ASW by the Canadian Navy. The
Bras d'Or was a surface-piercing type which performed well during her trials, reaching a maximum speed of 63 knots.
The
Soviet Union experimented extensively with hydrofoils, constructing hydrofoil
ferries with streamlined designs, especially during the
1970s and
1980s. Such vessels include the
Meteor type and the smaller
Voskhod type; these vessels have inspired people in the former Soviet Union to continue tinkering with hydrofoils and selling them to hydrofoil operators.
The
U.S. Navy operated combat hydrofoils, such as the
Pegasus class, from
1977 through
1993. These hydrofoils were fast and well armed, and were capable of sinking all but the largest surface vessels. In their
narcotics interdiction role, they were a nightmare for
drug runners, being very fast, and having missiles and guns to stop anything they could not catch, as well as the ability to call in air support.
The
Italian Navy has used 6 hydrofoils of the
Nibbio class from the late
1970s. These were armed with a 76 mm gun, two missiles and were capable of speed up to 50 knots.
Some operators of hydrofoil include:
*
TurboJET service, which speeds passengers across the
Pearl River Delta between
Hong Kong and
Macau in less than an hour, with an average speed of 45 knots (83km/h), mainly using
Boeing's Jetfoil. Also services
Shenzhen,
Guangzhou and
Kowloon. Operated by Shun Tak-China Travel Ship Management Limited.
*
Meteor service between
St. Petersburg,
Russia and the
Peterhof island,
Peter the Great's Summer Palace.
*
Linda Line between
Tallinn and
Helsinki using Soviet built
Meteor boats.
*
Navigazione Lago Maggiore provides fast and reliable boat services with hydrofoils on the
Lake Maggiore between
Locarno and
Arona. Former Russian hydrofoils are used in southern Italy for connection with islands of
Latium and
Campania.
*
Beetle service between
Pusan,
South Korea and
Fukuoka,
Japan, it services five times a day, mainly using Boeing's Jetfoil.
* Regular hydrofoil service from
Istanbul to
Yalova*
Fast Flying Ferries operated by
Connexxion, provides a regular
public transport service over the
North Sea Canal between
Amsterdam Central Station and
Velsen-Zuid in
The Netherlands, using Voshkod 2M hydrofoils.
* Flying Dolfins operate in many lines in the Aegean, between the Cycladic islands and Athens.
 |
A Meteor in China on the Yangtze River, running downstream fast on its hydrofoils. |
*
Riverboat*
Hydroplaning*
Boeing's Jetfoil*
Turbojet - Hong Kong to Macau Ferry*
Human-Powered-Hydrofoils.com*
Human powered hydrofoil examples*
The International Hydrofoil Society*
Kawasaki Jetfoil*
Directory of Soviet-made hydrofoils* Seminal
NACA reports:
**
1958-hydroplaning**
1955-hydrofoil
