foil
Foil may refer to:
Materials
* Foil (metal), a quite thin sheet of metal, usually manufactured with a rolling mill machine
* Metal leaf, a very thin sheet of decorative metal
* Aluminium foil, a type of wrapping for food
* Tin foil, metal foil ma ...
, that operates in water. They are similar in appearance and purpose to aerofoils used by
aeroplane
An airplane (American English), or aeroplane (Commonwealth English), informally plane, is a fixed-wing aircraft that is propelled forward by thrust from a jet engine, Propeller (aircraft), propeller, or rocket engine. Airplanes come in a vari ...
s.
Boat
A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size or capacity, its shape, or its ability to carry boats.
Small boats are typically used on inland waterways s ...
s that use hydrofoil technology are also simply termed hydrofoils. As a hydrofoil craft gains speed, the hydrofoils lift the boat's hull out of the water, decreasing drag and allowing greater speeds.
Description
The hydrofoil was created by Eric Walters. The hydrofoil usually consists of a
wing
A wing is a type of fin that produces both Lift (force), lift and drag while moving through air. Wings are defined by two shape characteristics, an airfoil section and a planform (aeronautics), planform. Wing efficiency is expressed as lift-to-d ...
like structure mounted on struts below the hull, or across the keels of a
catamaran
A catamaran () (informally, a "cat") is a watercraft with two parallel hull (watercraft), hulls of equal size. The wide distance between a catamaran's hulls imparts stability through resistance to rolling and overturning; no ballast is requi ...
in a variety of boats (see illustration). As a hydrofoil-equipped watercraft increases in speed, the hydrofoil elements below the hull(s) develop enough lift to raise the hull out of the water, which greatly reduces hull drag. This provides a corresponding increase in
speed
In kinematics, the speed (commonly referred to as ''v'') of an object is the magnitude of the change of its position over time or the magnitude of the change of its position per unit of time; it is thus a non-negative scalar quantity. Intro ...
and
fuel efficiency
Fuel efficiency (or fuel economy) is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical energy, chemical potential energy contained in a carrier (fuel) into kinetic energy or Mechanical work, w ...
.
Wider adoption of hydrofoils is prevented by the increased complexity of building and maintaining them. Hydrofoils are generally prohibitively more expensive than conventional watercraft above a certain displacement, so most hydrofoil craft are relatively small, and are mainly used as high-speed passenger ferries, where the relatively high passenger fees can offset the high cost of the craft itself. However, the design is simple enough that there are many human-powered hydrofoil designs. Amateur experimentation and development of the concept is popular.
Hydrodynamic mechanics
Since air and water are governed by similar fluid equations—albeit with different levels of
viscosity
Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for e ...
,
density
Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...
airfoil
An airfoil (American English) or aerofoil (British English) is a streamlined body that is capable of generating significantly more Lift (force), lift than Drag (physics), drag. Wings, sails and propeller blades are examples of airfoils. Foil (fl ...
(both types of
foil
Foil may refer to:
Materials
* Foil (metal), a quite thin sheet of metal, usually manufactured with a rolling mill machine
* Metal leaf, a very thin sheet of decorative metal
* Aluminium foil, a type of wrapping for food
* Tin foil, metal foil ma ...
) create lift in identical ways. The foil shape moves smoothly through the water, deflecting the flow downward, which, following the
Euler equations
In mathematics and physics, many topics are eponym, named in honor of Swiss mathematician Leonhard Euler (1707–1783), who made many important discoveries and innovations. Many of these items named after Euler include their own unique function, e ...
, exerts an upward force on the foil. This turning of the water creates higher pressure on the bottom of the foil and reduced pressure on the top. This pressure difference is accompanied by a velocity difference, via Bernoulli's principle, so the resulting flow field about the foil has a higher average velocity on one side than the other.
When used as a lifting element on a hydrofoil boat, this upward force lifts the body of the vessel, decreasing drag and increasing speed. The lifting force eventually balances with the weight of the craft, reaching a point where the hydrofoil no longer lifts out of the water but remains in equilibrium. Since wave resistance and other impeding forces such as various types of
drag (physics)
In fluid dynamics, drag, sometimes referred to as fluid resistance, is a force acting opposite to the direction of motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers, two solid surfaces, or b ...
on the hull are eliminated as the hull lifts clear, turbulence and drag act increasingly on the much smaller surface area of the hydrofoil, and decreasingly on the hull, creating a marked increase in speed.
Foil configurations
Early hydrofoils used V-shaped foils. Hydrofoils of this type are known as "surface-piercing" since portions of the V-shape hydrofoils rise above the water surface when foilborne. Some modern hydrofoils use fully submerged inverted T-shape foils. Fully submerged hydrofoils are less subject to the effects of wave action, and, therefore, more stable at sea and more comfortable for crew and passengers. This type of configuration, however, is not self-stabilizing. The angle of attack on the hydrofoils must be adjusted continuously to changing conditions, a control process performed by sensors, a computer, and active surfaces.
History
Prototypes
The first evidence of a hydrofoil on a vessel appears on a British patent granted in 1869 to Emmanuel Denis Farcot, a Parisian. He claimed that "adapting to the sides and bottom of the vessel a series or inclined planes or wedge formed pieces, which as the vessel is driven forward will have the effect of lifting it in the water and reducing the draught.". Italian inventor Enrico Forlanini began work on hydrofoils in 1898 and used a "ladder" foil system. Forlanini obtained patents in Britain and the United States for his ideas and designs.
Between 1899 and 1901, British boat designer John Thornycroft worked on a series of models with a stepped hull and single bow foil. In 1909 his company built the full scale long boat, ''Miranda III''. Driven by a engine, it rode on a bowfoil and flat stern. The subsequent ''Miranda IV'' was credited with a speed of .
In May 1904 a hydrofoil boat was described being tested on the River Seine "in the neighbourhood of
Paris
Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...
". This boat was designed by Comte de Lambert. This had 5 variable pitch fins on the hull beneath the water so inclined that when the boat begins to move "the boat rises and the planes come to the surface" with the result that "it skims over the surface with little but the propellers beneath the surface". The boat had twin hulls 18-foot long connected by a single deck 9-foot wide, and was fitted with a 14HP De Dion-Bouton motor, the boat was reported to have reached 20 mph. It was stated that "The boat running practically on its fins resembles an aeroplane".
A March 1906
Scientific American
''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it, with more than 150 Nobel Pri ...
article by American hydrofoil pioneer William E. Meacham explained the basic principle of hydrofoils.
Alexander Graham Bell
Alexander Graham Bell (; born Alexander Bell; March 3, 1847 – August 2, 1922) was a Scottish-born Canadian Americans, Canadian-American inventor, scientist, and engineer who is credited with patenting the first practical telephone. He als ...
considered the invention of the hydroplane (now regarded as a distinct type, but also employing lift) a very significant achievement, and after reading the article began to sketch concepts of what is now called a hydrofoil boat. With his chief engineer Casey Baldwin, Bell began hydrofoil experiments in the summer of 1908. Baldwin studied the work of the Italian inventor Enrico Forlanini and began testing models based on those designs, which led to the development of hydrofoil watercraft. During Bell's world tour of 1910–1911, Bell and Baldwin met with Forlanini in Italy, where they rode in his hydrofoil boat over Lake Maggiore. Baldwin described it as being as smooth as flying.
On returning to Bell's large laboratory at his Beinn Bhreagh estate near Baddeck, Nova Scotia, they experimented with a number of designs, culminating in Bell's ''
HD-4
''HD-4'' or ''Hydrodome number 4'' was an early research hydrofoil watercraft developed by the scientist Alexander Graham Bell. It was designed and built at the Bell Boatyard on Bell's Beinn Bhreagh estate near Baddeck, Nova Scotia. In 191 ...
''. Using
Renault
Renault S.A., commonly referred to as Groupe Renault ( , , , also known as the Renault Group in English), is a French Multinational corporation, multinational Automotive industry, automobile manufacturer established in 1899. The company curr ...
engines, a top speed of was achieved, accelerating rapidly, taking waves without difficulty, steering well and showing good stability. Bell's report to the
United States Navy
The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...
permitted him to obtain two engines. On 9 September 1919 the ''HD-4'' set a world marine speed record of , which stood for two decades. A full-scale replica of the ''HD-4'' is viewable at the Alexander Graham Bell National Historic Site museum in Baddeck, Nova Scotia.
In the early 1950s an English couple built the ''White Hawk'', a jet-powered hydrofoil water craft, in an attempt to beat the absolute water speed record. However, in tests, ''White Hawk'' could barely top the record breaking speed of the 1919 ''HD-4''. The designers had faced an engineering phenomenon that limits the top speed of even modern hydrofoils:
cavitation
Cavitation in fluid mechanics and engineering normally is the phenomenon in which the static pressure of a liquid reduces to below the liquid's vapor pressure, leading to the formation of small vapor-filled cavities in the liquid. When sub ...
disturbs the lift created by the foils as they move through the water at speed above , bending the lifting foil.
First passenger boats
German engineer Hanns von Schertel worked on hydrofoils prior to and during
World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
in
Germany
Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
. After the war, the Russians captured Schertel's team. As Germany was not authorized to build fast boats, Schertel went to
Switzerland
Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...
, where he established the Supramar company. In 1952, Supramar launched the first commercial hydrofoil, PT10 "Freccia d'Oro" (Golden Arrow), in Lake Maggiore, between Switzerland and
Italy
Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...
. The PT10 is of surface-piercing type, it can carry 32 passengers and travel at . In 1968, the Bahraini born banker Hussain Najadi acquired the Supramar AG and expanded its operations into Japan, Hong Kong, Singapore, the UK, Norway and the US. General Dynamics of the United States became its licensee, and the Pentagon awarded its first R&D naval research project in the field of supercavitation.
Hitachi
() is a Japanese Multinational corporation, multinational Conglomerate (company), conglomerate founded in 1910 and headquartered in Chiyoda, Tokyo. The company is active in various industries, including digital systems, power and renewable ener ...
Shipbuilding of Osaka, Japan, was another licensee of Supramar, as well as many leading ship owners and shipyards in the OECD countries.
From 1952 to 1971, Supramar designed many models of hydrofoils: PT20, PT50, PT75, PT100 and PT150. All are of surface-piercing type, except the PT150 combining a surface-piercing foil forward with a fully submerged foil in the aft location. Over 200 of Supramar's design were built, most of them by Rodriquez (headed at the time by Engineer Carlo Rodriquez in
Sicily
Sicily (Italian language, Italian and ), officially the Sicilian Region (), is an island in the central Mediterranean Sea, south of the Italian Peninsula in continental Europe and is one of the 20 regions of Italy, regions of Italy. With 4. ...
, Italy.
During the same period the
Soviet Union
The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
experimented extensively with hydrofoils, constructing hydrofoil river boats and
ferries
A ferry is a boat or ship that transports passengers, and occasionally vehicles and cargo, across a body of water. A small passenger ferry with multiple stops, like those in Venice, Italy, is sometimes referred to as a water taxi or water bus.
...
with streamlined designs during the cold war period and into the 1980s. Such vessels include the Raketa (1957) type, followed by the larger
Meteor
A meteor, known colloquially as a shooting star, is a glowing streak of a small body (usually meteoroid) going through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere,
creating a ...
type and the smaller Voskhod type. One of the most successful Soviet designer/inventor in this area was Rostislav Alexeyev, who some consider the 'father' of the modern hydrofoil due to his 1950s era high speed hydrofoil designs. Later, circa 1970s, Alexeyev combined his hydrofoil experience with the surface effect principle to create the Ekranoplan. Extensive investment in this type of technology in the USSR resulted in the largest civil hydrofoil fleet in the world and the making of the Meteor type, the most successful hydrofoil in history, with more than 400 units built.
Peterhof hydrofoil (18272163540).jpg, Voskhod
Meteor boat on Neva Bay.jpg,
Meteor
A meteor, known colloquially as a shooting star, is a glowing streak of a small body (usually meteoroid) going through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere,
creating a ...
Raketa-185 on Khimki Reservoir 6-jun-2014 02.jpg, Raketa
Polesye-1 (ship, 1986, Gomel, 7).jpg, Polesye
Kizhi 06-2017 img30 Kometa-17 hydrofoil.jpg, Kometa
In 1961,
SRI International
SRI International (SRI) is a nonprofit organization, nonprofit scientific research, scientific research institute and organization headquartered in Menlo Park, California, United States. It was established in 1946 by trustees of Stanford Univer ...
issued a study on "The Economic Feasibility of Passenger Hydrofoil Craft in US Domestic and Foreign Commerce". Commercial use of hydrofoils in the US first appeared in 1961 when two commuter vessels were commissioned by Harry Gale Nye, Jr.'s North American Hydrofoils to service the route from Atlantic Highlands, New Jersey to the financial district of Lower Manhattan.
Military usage
Germany
A 17-ton German craft ''VS-6 Hydrofoil'' was designed and constructed in 1940, completed in 1941 for use as a mine layer; it was tested in the
Baltic Sea
The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by the countries of Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden, and the North European Plain, North and Central European Plain regions. It is the ...
, producing speeds of 47 knots. Tested against a standard E-boat over the next three years it performed well but was not brought into production. Being faster it could carry a higher payload and was capable of travelling over minefields but was prone to damage and noisier.
Canada
In Canada during World War II, Baldwin worked on an experimental smoke laying hydrofoil (later called the Comox Torpedo) that was later superseded by other smoke-laying technology and an experimental target-towing hydrofoil. The forward two foil assemblies of what is believed to be the latter hydrofoil were salvaged in the mid-1960s from a derelict hulk in Baddeck, Nova Scotia by Colin MacGregor Stevens. These were donated to the Maritime Museum in Halifax, Nova Scotia.
The
Canadian Armed Forces
The Canadian Armed Forces (CAF; , FAC) are the unified Military, military forces of Canada, including sea, land, and air commands referred to as the Royal Canadian Navy, Canadian Army and the Royal Canadian Air Force. Under the ''National Defenc ...
built and tested a number of hydrofoils (e.g., Baddeck and two vessels named ''Bras d'Or''), which culminated in the high-speed anti-submarine hydrofoil HMCS ''Bras d'Or'' in the late 1960s. However, the program was cancelled in the early 1970s due to a shift away from
anti-submarine warfare
Anti-submarine warfare (ASW, or in the older form A/S) is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations ar ...
by the Canadian military. The ''Bras d'Or'' was a surface-piercing type that performed well during her trials, reaching a maximum speed of .
US Navy
The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...
began experiments with hydrofoils in the mid-1950s by funding a sailing vessel that used hydrofoils to reach speeds in the 30 mph range. The ''XCH-4'' (officially, ''Experimental Craft, Hydrofoil No. 4''), designed by William P. Carl, exceeded speeds of and was mistaken for a seaplane due to its shape. ''Halobates'' was a 1957 US Navy prototype hydrofoil boat built by Miami Shipbuilding.
The US Navy implemented a small number of combat hydrofoils, such as the ''Pegasus'' class, from 1977 through 1993. These hydrofoils were fast and well armed.
Italy
The
Italian Navy
The Italian Navy (; abbreviated as MM) is one of the four branches of Italian Armed Forces and was formed in 1946 from what remained of the ''Regia Marina'' (Royal Navy) after World War II. , the Italian Navy had a strength of 30,923 active per ...
used six hydrofoils of the ''Sparviero'' class starting in the late 1970s. These were armed with a 76 mm gun and two missiles, and were capable of speeds up to . Three similar boats were built for the Japan Maritime Self-Defense Force.
Sailing and sports
Several editions of the America's Cup have been raced with foiling yachts. The 2013 and 2017 editions used the AC72 and AC50 classes of
catamaran
A catamaran () (informally, a "cat") is a watercraft with two parallel hull (watercraft), hulls of equal size. The wide distance between a catamaran's hulls imparts stability through resistance to rolling and overturning; no ballast is requi ...
respectively, and the 2021 edition used the AC75 class of foiling monohulls with canting arms.
The French experimental sail-powered hydrofoil '' Hydroptère'' is the result of a research project that involves advanced engineering skills and technologies. In September 2009, the ''Hydroptère'' set new sailcraft world speed records in the 500 m category, with a speed of and in the category with a speed of .
The 500 m speed record for sailboats is currently held by the '' Vestas Sailrocket'', an exotic design which operates in effect as a hydrofoil.
Another trimaran sailboat is the Windrider Rave. The Rave is a commercially available , two person, hydrofoil trimaran, capable of reaching speeds of . The boat was designed by Jim Brown.
The Moth dinghy has evolved into some radical foil configurations.
Hobie Sailboats produced a production foiling
trimaran
A trimaran (or double-outrigger) is a multihull boat that comprises a main hull and two smaller outrigger hulls (or "floats") which are attached to the main hull with lateral beams. Most modern trimarans are sailing yachts designed for recrea ...
, the Hobie Trifoiler, the fastest production sailboat. Trifoilers have clocked speeds upward of thirty knots.
A new kayak design, called Flyak, has hydrofoils that lift the kayak enough to significantly reduce drag, allowing speeds of up to . Some surfers have developed surfboards with hydrofoils called
foilboard
A foilboard, also known as a hydrofoil board or foil surfboard, is a type of board used in water sports; it is distinct from surfboards in that it has a hydrofoil rather than fins mounted underneath. This hydrofoil design allows the surfboard and ...
s, specifically aimed at surfing big waves further out to sea.
Quadrofoil Q2 is a two-seater, four-foiled hydrofoil electrical leisure watercraft. Its initial design was set in 2012 and it has been available commercially since the end of 2016. Powered by a 5.2-kWh lithium-ion battery pack and propelled by a 5.5 kW motor, it reaches the top speed of 40 km/h and has 80 km of range.
The Manta5 Hydrofoiler XE-1 is a Hydrofoil E-bike, designed and built in
New Zealand
New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
that has since been available commercially for pre-order since late 2017. Propelled by a 400 watt motor, it can reach speeds exceeding 14 km/h with a weight of 22 kg. A single charge of the battery lasts an hour for a rider weighing 85 kg.
Candela, a Swedish company, is producing a recreational hydrofoil powerboat, making strong claims for efficiency, performance, and range.
Hydrofoils are now widely used with kitesurfing, that is traction kites over water. Hydrofoils are a new trend in
windsurfing
Windsurfing is a wind-propelled water sport that is a combination of sailing and surfing. It is also referred to as "sailboarding" and "boardsailing", and emerged in the late 1960s from the Californian aerospace and surf culture. Windsurfing gain ...
- including the new Summer Olympic class, the IQFoil, and more recently with
Wing foiling
Wing foiling or wing surfing or winging is a wind propelled water sport that developed from kitesurfing, windsurfing and surfing. The sailor, standing on a board, holds directly onto a wing. It generates both upward force and horizontal force whi ...
, which are essentially a kite with no strings, or a hand-held sail.
Modern passenger boats
Soviet-built Voskhods are one of the most successful passenger hydrofoil designs. Manufactured in Soviet and later Ukrainian Crimea, they are in service in more than 20 countries. The most recent model, Voskhod-2M FFF, also known as Eurofoil, was built in Feodosiya for the Dutch public transport operator Connexxion.
Mid-2010s saw a Russian governmental program aimed at restoring passenger hydrofoil production. The , based on the earlier , Kolhida and Katran models, became the first to enter production, initially on factory in Rybinsk, and later on More shipyard in Feodosiya. Since 2018, the ships are running Sevastopol-Yalta and Sochi-Gelenzhik-Novorossiysk, with a Sevastopol-Sochi connection in the immediate plans in 2021. At the same time, the Alekseyev Bureau began building lighter, smaller hydrofoils, based on a widely successful model, at its own plant in Nizhny Novgorod, the relatively shallow-draft boats used on the Ob and the Volga. The , a development of the , became the Valday's larger sibling, the first ship launched in Nizhny Novgorod in August 2021.
The Boeing 929 is widely used in
Asia
Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...
for passenger services, between
Hong Kong
Hong Kong)., Legally Hong Kong, China in international treaties and organizations. is a special administrative region of China. With 7.5 million residents in a territory, Hong Kong is the fourth most densely populated region in the wor ...
and
Macau
Macau or Macao is a special administrative regions of China, special administrative region of the People's Republic of China (PRC). With a population of about people and a land area of , it is the most List of countries and dependencies by p ...
and between the many islands of
Japan
Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
. It was also used between
Kyushu
is the third-largest island of Japan's Japanese archipelago, four main islands and the most southerly of the four largest islands (i.e. excluding Okinawa Island, Okinawa and the other Ryukyu Islands, Ryukyu (''Nansei'') Ryukyu Islands, Islands ...
of Japan and
Korean peninsula
Korea is a peninsular region in East Asia consisting of the Korean Peninsula, Jeju Island, and smaller islands. Since the end of World War II in 1945, it has been politically divided at or near the 38th parallel between North Korea (Dem ...
. Hong Kong ferry company
TurboJET
The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...
was the main user of Boeing 929.
Current operation
Current operators of hydrofoils include:
*
TurboJET
The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...
service, which speeds passengers across the
Pearl River Delta
The Pearl River Delta Metropolitan Region is the low-lying area surrounding the Pearl River estuary, where the Pearl River flows into the South China Sea. Referred to as the Guangdong–Hong Kong–Macao Greater Bay Area in official documents, ...
between
Hong Kong
Hong Kong)., Legally Hong Kong, China in international treaties and organizations. is a special administrative region of China. With 7.5 million residents in a territory, Hong Kong is the fourth most densely populated region in the wor ...
and
Macau
Macau or Macao is a special administrative regions of China, special administrative region of the People's Republic of China (PRC). With a population of about people and a land area of , it is the most List of countries and dependencies by p ...
in less than an hour, with an average speed of , mainly using
Boeing
The Boeing Company, or simply Boeing (), is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, and missiles worldwide. The company also provides leasing and product support s ...
COVID-19 pandemic
The COVID-19 pandemic (also known as the coronavirus pandemic and COVID pandemic), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began with an disease outbreak, outbreak of COVID-19 in Wuhan, China, in December ...
. After service resumption in 2023, only one Jetfoil and one Foilcat re-entered into service. Also serviced
Shenzhen
Shenzhen is a prefecture-level city in the province of Guangdong, China. A Special economic zones of China, special economic zone, it is located on the east bank of the Pearl River (China), Pearl River estuary on the central coast of Guangdong ...
Kowloon
Kowloon () is one of the areas of Hong Kong, three areas of Hong Kong, along with Hong Kong Island and the New Territories. It is an urban area comprising the Kowloon Peninsula and New Kowloon. It has a population of 2,019,533 and a populat ...
. Operated by Shun Tak-China Travel Ship Management Limited.
* Voskhod and ''Polesye'' service between
Tulcea
Tulcea (; also known by #Names, alternative names) is a city in Northern Dobruja, Romania. It is the administrative center of Tulcea County, and had a population of 65,624 . One village, Tudor Vladimirescu, is administered by the city. It is one ...
Danube
The Danube ( ; see also #Names and etymology, other names) is the List of rivers of Europe#Longest rivers, second-longest river in Europe, after the Volga in Russia. It flows through Central and Southeastern Europe, from the Black Forest sou ...
.
* ''Meteor'' and ''Polesye'' service in
Poland
Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...
between
Szczecin
Szczecin ( , , ; ; ; or ) is the capital city, capital and largest city of the West Pomeranian Voivodeship in northwestern Poland. Located near the Baltic Sea and the Poland-Germany border, German border, it is a major port, seaport, the la ...
Irkutsk
Irkutsk ( ; rus, Иркутск, p=ɪrˈkutsk; Buryat language, Buryat and , ''Erhüü'', ) is the largest city and administrative center of Irkutsk Oblast, Russia. With a population of 587,891 Irkutsk is the List of cities and towns in Russ ...
on
Lake Baikal
Lake Baikal is a rift lake and the deepest lake in the world. It is situated in southern Siberia, Russia between the Federal subjects of Russia, federal subjects of Irkutsk Oblast, Irkutsk Oblasts of Russia, Oblast to the northwest and the Repu ...
Belarus
Belarus, officially the Republic of Belarus, is a landlocked country in Eastern Europe. It is bordered by Russia to the east and northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Belarus spans an a ...
).
* ''Meteor'' service between
Saint Petersburg
Saint Petersburg, formerly known as Petrograd and later Leningrad, is the List of cities and towns in Russia by population, second-largest city in Russia after Moscow. It is situated on the Neva, River Neva, at the head of the Gulf of Finland ...
,
Russia
Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
and the Peterhof Palace, a summer palace of Russian tsars.
* ''Meteor'' service between
Saint Petersburg
Saint Petersburg, formerly known as Petrograd and later Leningrad, is the List of cities and towns in Russia by population, second-largest city in Russia after Moscow. It is situated on the Neva, River Neva, at the head of the Gulf of Finland ...
,
Russia
Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
and the Kronstadt, a strongly fortified Russian seaport town, located on Kotlin Island, near the head of the Gulf of Finland. It lies thirty kilometers west of Saint Petersburg. Since 2012 replaced by a catamaran ''Mercury''.
* ''Meteor'', ''Raketa'' and ''Voskhod'' hydrofoil types operate all over
Volga
The Volga (, ) is the longest river in Europe and the longest endorheic basin river in the world. Situated in Russia, it flows through Central Russia to Southern Russia and into the Caspian Sea. The Volga has a length of , and a catchment ...
Russia
Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
. Also the Lena River and Amur River.
* ''Meteor'' hydrofoils are operated by a number of tour operators in
Croatia
Croatia, officially the Republic of Croatia, is a country in Central Europe, Central and Southeast Europe, on the coast of the Adriatic Sea. It borders Slovenia to the northwest, Hungary to the northeast, Serbia to the east, Bosnia and Herze ...
, mostly for packaged tours, but there are also some scheduled services to islands in Adriatic.
* In Italy hydrofoils have been used for commercial connections since 1956, by the Rodriguez shipyards and the SNAV company. Currently (2025), the main hydrofoil operator in Italy is Liberty Lines, which operates connections between the smaller Sicilian islands ( Aeolian Island, Aegadian Island, Pelagie Islands, Ustica and
Pantelleria
Pantelleria (; ), known in ancient times as Cossyra or Cossura, is an Italian island and comune in the Strait of Sicily in the Mediterranean Sea, southwest of Sicily and east of the Tunisian coast. On clear days Tunisia is visible from the ...
) with
Sicily
Sicily (Italian language, Italian and ), officially the Sicilian Region (), is an island in the central Mediterranean Sea, south of the Italian Peninsula in continental Europe and is one of the 20 regions of Italy, regions of Italy. With 4. ...
and
Calabria
Calabria is a Regions of Italy, region in Southern Italy. It is a peninsula bordered by the region Basilicata to the north, the Ionian Sea to the east, the Strait of Messina to the southwest, which separates it from Sicily, and the Tyrrhenian S ...
Messina
Messina ( , ; ; ; ) is a harbour city and the capital city, capital of the Italian Metropolitan City of Messina. It is the third largest city on the island of Sicily, and the 13th largest city in Italy, with a population of 216,918 inhabitants ...
and
Reggio Calabria
Reggio di Calabria (; ), commonly and officially referred to as Reggio Calabria, or simply Reggio by its inhabitants, is the List of cities in Italy, largest city in Calabria as well as the seat of the Metropolitan City of Reggio Calabria. As ...
) and between
Trieste
Trieste ( , ; ) is a city and seaport in northeastern Italy. It is the capital and largest city of the Regions of Italy#Autonomous regions with special statute, autonomous region of Friuli-Venezia Giulia, as well as of the Province of Trieste, ...
and
Mali Lošinj
Mali Lošinj is a town in the Primorje-Gorski Kotar County, on the island of Lošinj, in western Croatia. At the time of the 2021 census, there were 7,537 inhabitants, of whom 86% were Croats. The town of Mali Lošinj itself had an urban populat ...
Naples
Naples ( ; ; ) is the Regions of Italy, regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 908,082 within the city's administrative limits as of 2025, while its Metropolitan City of N ...
Locarno
Locarno (; ; Ticinese dialect, Ticinese: ; formerly in ) is a southern Switzerland, Swiss List of towns in Switzerland, town and Municipalities of Switzerland, municipality in the district Locarno (district), Locarno (of which it is the capita ...
Lake Garda
Lake Garda (, , or , ; ; ) is the largest lake in Italy. It is a popular holiday location in northern Italy, between Brescia and Milan to the west, and Verona and Venice to the east. The lake cuts into the edge of the Eastern Alps, Italian Alp ...
. Three units of the Rodriguez RHS150 type operate on each lake, for a total of nine hydrofoils. At least until 2024, former Russian hydrofoils was used in southern Italy for connection with islands of
Lazio
Lazio ( , ; ) or Latium ( , ; from Latium, the original Latin name, ) is one of the 20 Regions of Italy, administrative regions of Italy. Situated in the Central Italy, central peninsular section of the country, it has 5,714,882 inhabitants an ...
and
Campania
Campania is an administrative Regions of Italy, region of Italy located in Southern Italy; most of it is in the south-western portion of the Italian Peninsula (with the Tyrrhenian Sea to its west), but it also includes the small Phlegraean Islan ...
by VETORaliscafi. SNAV had five RHS200, RHS160 and RHS150 used in the connections between
Naples
Naples ( ; ; ) is the Regions of Italy, regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 908,082 within the city's administrative limits as of 2025, while its Metropolitan City of N ...
and the islands of
Capri
Capri ( , ; ) is an island located in the Tyrrhenian Sea off the Sorrento Peninsula, on the south side of the Gulf of Naples in the Campania region of Italy. A popular resort destination since the time of the Roman Republic, its natural beauty ...
and Ischia, now mainly replaced by catamarans (the only hydrofoil left in the SNAV fleet, the RHS200 Super Jumbo, connect Naples and the Aeolian Islands in summer).
* A regular hydrofoil service runs from
Istanbul
Istanbul is the List of largest cities and towns in Turkey, largest city in Turkey, constituting the country's economic, cultural, and historical heart. With Demographics of Istanbul, a population over , it is home to 18% of the Demographics ...
to
Yalova
Yalova is a market-gardening town located in northwestern Turkey on the eastern coast of the Sea of Marmara. It is the seat of Yalova Province and Yalova District.Hellenic Seaways operate their Flying Dolphins service over many routes in the Aegean, between the
Cyclades
The CYCLADES computer network () was a French research network created in the early 1970s. It was one of the pioneering networks experimenting with the concept of packet switching and, unlike the ARPANET, was explicitly designed to facilitate i ...
, Saronic Gulf islands such as Aegina and Poros, and
Athens
Athens ( ) is the Capital city, capital and List of cities and towns in Greece, largest city of Greece. A significant coastal urban area in the Mediterranean, Athens is also the capital of the Attica (region), Attica region and is the southe ...
.
* ''Meteor'' (2), ''Polesye'' (4) and ''Voskhod'' (3) hydrofoil types operate in
Hungary
Hungary is a landlocked country in Central Europe. Spanning much of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and ...
. MAHART PassNave Ltd. operates scheduled hydrofoil liners between
Budapest
Budapest is the Capital city, capital and List of cities and towns of Hungary, most populous city of Hungary. It is the List of cities in the European Union by population within city limits, tenth-largest city in the European Union by popul ...
,
Bratislava
Bratislava (German: ''Pressburg'', Hungarian: ''Pozsony'') is the Capital city, capital and largest city of the Slovakia, Slovak Republic and the fourth largest of all List of cities and towns on the river Danube, cities on the river Danube. ...
and
Vienna
Vienna ( ; ; ) is the capital city, capital, List of largest cities in Austria, most populous city, and one of Federal states of Austria, nine federal states of Austria. It is Austria's primate city, with just over two million inhabitants. ...
, inland liners between Budapest and the Danube Bend, and theme cruises to Komárom, Solt, Kalocsa and Mohács.
* "Kometa" Flying Dolphin services are currently operated by Joy Cruises between
Corfu
Corfu ( , ) or Kerkyra (, ) is a Greece, Greek island in the Ionian Sea, of the Ionian Islands; including its Greek islands, small satellite islands, it forms the margin of Greece's northwestern frontier. The island is part of the Corfu (regio ...
and Paxos. They run from Corfu Port to Gaios using two hydrofoils: ''Ilida'' and ''Ilida II''. The company operates also an international service from Corfu to Saranda (Albania) using the hydrofoil ''Ilida Dolphin'' of the same type.
* "Kometa" type hydrofoils (registered in Albania) are operated by Ionian Cruises and Finikas Lines between Saranda and Corfu.
* Russian hydrofoils of the ''Kometa'' type operated on the Bulgarian Black Sea Coast connecting Varna, Nesebar,
Burgas
Burgas (, ), sometimes transliterated as Bourgas, is the second largest city on the Bulgarian Black Sea Coast in the region of Northern Thrace and the List of cities and towns in Bulgaria, fourth-largest city in Bulgaria after Sofia, Plovdiv, an ...
, Sozopol, Primorsko, and Tsarevo, and ''Raketa'' and ''Meteor'' models served the Bulgarian
Danube
The Danube ( ; see also #Names and etymology, other names) is the List of rivers of Europe#Longest rivers, second-longest river in Europe, after the Volga in Russia. It flows through Central and Southeastern Europe, from the Black Forest sou ...
ports between
Rousse
Ruse (also transliterated as Rousse, Russe; ) is the List of cities and towns in Bulgaria, fifth-largest city in Bulgaria. Ruse is in the northeastern part of the country, on the right bank of the Danube, opposite the Romanian city of Giurgiu, ...
and Vidin. Both services were discontinued in the 1990s. In 2011 the service reopened between Varna, Nesebar, Burgas and Sozopol, operated by Bulgarian Hydrofoils Ltd.
* Vietnamese ''Greenline Company'' operates hourly shuttle service between
Ho Chi Minh City
Ho Chi Minh City (HCMC) ('','' TP.HCM; ), commonly known as Saigon (; ), is the most populous city in Vietnam with a population of around 14 million in 2025.
The city's geography is defined by rivers and canals, of which the largest is Saigo ...
, Vung Tau and Con Dao island. Hydrofoil lines using the Russian-built Meteor type also connect Hai Phong,
Ha Long
Ha may refer to:
Agencies and organizations
* Health authority, a former type of administrative organisation of the NHS in England and Wales
* Hells Angels Motorcycle Club
* Highways Agency (renamed ''Highways England'', now ''National Highways ...
Busan
Busan (), officially Busan Metropolitan City, is South Korea's second list of cities in South Korea by population, most populous city after Seoul, with a population of over 3.3 million as of 2024. Formerly romanized as Pusan, it is the economi ...
,
South Korea
South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...
and
Fukuoka
is the List of Japanese cities by population, sixth-largest city in Japan and the capital city of Fukuoka Prefecture, Japan. The city is built along the shores of Hakata Bay, and has been a center of international commerce since ancient times. ...
,
Japan
Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
Beetle
Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
'' five times a day. Korean Miraejet operates '' Kobee'' three to four times a day. All of their fleets are Boeing 929.
*As of February 2008, all of the commercial lines in Japan use Boeing 929. The routes include:
** Sado Kisen operates the route between Sado and Niigata.
** Tōkai Kisen operates ''Seven Islands'', running between
Tokyo
Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most ...
Fukuoka
is the List of Japanese cities by population, sixth-largest city in Japan and the capital city of Fukuoka Prefecture, Japan. The city is built along the shores of Hakata Bay, and has been a center of international commerce since ancient times. ...
Kagoshima
, is the capital Cities of Japan, city of Kagoshima Prefecture, Japan. , the city had an estimated population of 583,966 in 285,992 households, and a population density of 1100 persons per km2. The total area of the city is .
Etymology
While the ...
and
Tanegashima
is one of the Ōsumi Islands belonging to Kagoshima Prefecture, Japan. The island, in area, is the second largest of the Ōsumi Islands, and has a population of 33,000 people. Access to the island is by ferry, or by air to New Tanegashima Airp ...
or Yakushima.
* In 2012, Agriculture, Fisheries and Conservation Department (AFCD) in
Hong Kong
Hong Kong)., Legally Hong Kong, China in international treaties and organizations. is a special administrative region of China. With 7.5 million residents in a territory, Hong Kong is the fourth most densely populated region in the wor ...
leased a 12-meter HAWC (Hydrofoil Assisted Water Craft), a
catamaran
A catamaran () (informally, a "cat") is a watercraft with two parallel hull (watercraft), hulls of equal size. The wide distance between a catamaran's hulls imparts stability through resistance to rolling and overturning; no ballast is requi ...
Ukraine
Ukraine is a country in Eastern Europe. It is the List of European countries by area, second-largest country in Europe after Russia, which Russia–Ukraine border, borders it to the east and northeast. Ukraine also borders Belarus to the nor ...
:
Nova Kakhovka
Nova Kakhovka (, ; ) is a List of cities in Ukraine, city in Kakhovka Raion, Kherson Oblast, southern Ukraine. Nova Kakhovka has been under Russian occupation of Kherson Oblast, Russian occupation since February 2022. Its estimated population ...
-
Kherson
Kherson (Ukrainian language, Ukrainian and , , ) is a port city in southern Ukraine that serves as the administrative centre of Kherson Oblast. Located by the Black Sea and on the Dnieper, Dnieper River, Kherson is the home to a major ship-bui ...
Mykolaiv
Mykolaiv ( ), also known as Nikolaev ( ) is a List of cities in Ukraine, city and a hromada (municipality) in southern Ukraine. Mykolaiv is the Administrative centre, administrative center of Mykolaiv Raion (Raions of Ukraine, district) and Myk ...
Crimea
Crimea ( ) is a peninsula in Eastern Europe, on the northern coast of the Black Sea, almost entirely surrounded by the Black Sea and the smaller Sea of Azov. The Isthmus of Perekop connects the peninsula to Kherson Oblast in mainland Ukrain ...
, with the plans to add two more and possible other routes in 2019.
Discontinued operations
* Until 31 December 2013, Fast Flying Ferries operated by Connexxion provided a regular
public transport
Public transport (also known as public transit, mass transit, or simply transit) are forms of transport available to the general public. It typically uses a fixed schedule, route and charges a fixed fare. There is no rigid definition of whic ...
Velsen-Zuid
Velsen-Zuid () is a town in the Dutch province of North Holland. It is a part of the municipality of Velsen, and lies about 9 km north of Haarlem.
Velsen-Zuid developed around the church founded by Willibrord in the 8th century. Between 18 ...
in the
Netherlands
, Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...
, using Voskhod 2M hydrofoils. It was stopped due to a new
speed limit
Speed limits on road traffic, as used in most countries, set the legal maximum speed at which vehicles may travel on a given stretch of road. Speed limits are generally indicated on a traffic sign reflecting the maximum permitted speed, express ...
.
* Between 1981 and 1990, Transmediterranea operated a service of hydrofoils connecting
Ceuta
Ceuta (, , ; ) is an Autonomous communities of Spain#Autonomous cities, autonomous city of Spain on the North African coast. Bordered by Morocco, it lies along the boundary between the Mediterranean Sea and the Atlantic Ocean. Ceuta is one of th ...
and
Algeciras
Algeciras () is a city and a municipalities in Spain, municipality of Spain belonging to the province of Cádiz, Andalusia. Located in the southern end of the Iberian Peninsula, near the Strait of Gibraltar, it is the largest city on the Bay of G ...
in the Strait of Gibraltar. The crossing took half an hour, in comparison to the hour and a half of conventional ferries. Due to the common extreme winds and storms that take place in winter in the Strait of Gibraltar, the service was replaced in 1990 by catamarans, which were also able to carry cars. At the peak of the year, in summer, there was a service every half an hour in each direction. This high-speed connection had a big impact on the development of Ceuta, facilitating one-day business trips to mainland Spain.
* Between 1964 and 1991 the Sydney hydrofoils operated on
Sydney Harbour
Port Jackson, commonly known as Sydney Harbour, is a ria, natural harbour on the east coast of Australia, around which Sydney was built. It consists of the waters of Sydney Harbour, Middle Harbour, North Harbour and the Lane Cove River, Lane ...
between
Circular Quay
Circular Quay is a harbour, former working port and now international passenger shipping terminal, public piazza and tourism precinct, heritage area, and transport node located in Sydney, New South Wales, Australia, on the northern edge of the ...
and Manly.
* Between 1969 and 1998 Red Funnel operated between
Southampton
Southampton is a port City status in the United Kingdom, city and unitary authority in Hampshire, England. It is located approximately southwest of London, west of Portsmouth, and southeast of Salisbury. Southampton had a population of 253, ...
and Cowes, Isle of Wight.
* During the 1970s and 1980s there were frequent services between
Belgrade
Belgrade is the Capital city, capital and List of cities in Serbia, largest city of Serbia. It is located at the confluence of the Sava and Danube rivers and at the crossroads of the Pannonian Basin, Pannonian Plain and the Balkan Peninsula. T ...
and Tekija in Đerdap gorge. The distance of was covered in 3 hours and 30 minutes downstream and 4 hours upstream.
* Between 1980 and 1981, B+I Line operated a Boeing 929 jetfoil, named ''Cú Na Mara'' (Hound of the Sea), between Liverpool and Dublin. The service was not successful and was discontinued at the end of the 1981 season.
* Between the 1960s and 1985 there were hydrofoils going between Malmö, Sweden and Copenhagen, Denmark. They were retired and exchanged for catamarans. The service got cancelled when the Öresund Bridge got built in the early 2000s.
* Condor Ferries operated six hydrofoil ferries over a 29-year period between the
Channel Islands
The Channel Islands are an archipelago in the English Channel, off the French coast of Normandy. They are divided into two Crown Dependencies: the Jersey, Bailiwick of Jersey, which is the largest of the islands; and the Bailiwick of Guernsey, ...
, the south coast of England and
Saint-Malo
Saint-Malo (, , ; Gallo language, Gallo: ; ) is a historic French port in Ille-et-Vilaine, Brittany (administrative region), Brittany.
The Fortification, walled city on the English Channel coast had a long history of piracy, earning much wealth ...
in France.
* Following the restoration of
Estonia
Estonia, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Ru ...
n independence in the 1990s, the regular ferry service between
Helsinki
Helsinki () is the Capital city, capital and most populous List of cities and towns in Finland, city in Finland. It is on the shore of the Gulf of Finland and is the seat of southern Finland's Uusimaa region. About people live in the municipali ...
and
Tallinn
Tallinn is the capital city, capital and List of cities in Estonia, most populous city of Estonia. Situated on a Tallinn Bay, bay in north Estonia, on the shore of the Gulf of Finland of the Baltic Sea, it has a population of (as of 2025) and ...
was augmented by Soviet built hydrofoils during the summer season in periods of good weather. The higher speed service competed with the traditional ro-ro ferries but allowed easy day trips for pedestrian travellers. They were ultimately replaced with high-speed catamarans that could also carry vehicles and have better seaworthiness; however, the latter ceased operations as the operator filed for bankruptcy in May 2018.
Foilboard
A foilboard, also known as a hydrofoil board or foil surfboard, is a type of board used in water sports; it is distinct from surfboards in that it has a hydrofoil rather than fins mounted underneath. This hydrofoil design allows the surfboard and ...
Planing (sailing)
Planing ( ) is the mode of operation for a waterborne craft in which its weight is predominantly supported by lift (force), hydrodynamic lift, rather than Hydrostatics, hydrostatic lift (buoyancy).
Many forms of marine transport make use of pl ...
Sailing hydrofoil
A sailing hydrofoil, hydrofoil sailboat, or hydrosail is a sailboat with wing-like hydrofoil, foils mounted under the hull (watercraft), hull. As the craft increases its speed the hydrofoils Lift (force), lift the hull up and out of the water, gr ...