paul ricard trimaran

THE STORY OF L'HYDROPTERE

A human and technological adventure

I: THE GENESIS

1969 éric tabarly crosses the route of the first offshore hydrofoil.

It all began in California at the end of the 60s: aboard Pen Duick IV, Éric Tabarly sailed alongside a strange boat that moved above the water, supported by hydrofoils. This sailboat is Williwaw: built by the American David Kieper, and designed more for ocean voyages, it is the first known transoceanic hydrofoil. With its heavy weight and overcrowded crew, Williwaw is not a thunderbolt... But something clicked in Éric Tabarly's head when he saw this boat fly. As someone who is always on the lookout for innovation, he instinctively understood the advantage of the foil: to free himself from some of the water's resistance by rising above it. He wants foils on his next multihull...

1974 The Tabarly-Dassault Aviation meeting

Dassault Aviation, the French manufacturer of fighter jets and business jets, has innovative know-how in the use of aeronautical aluminum panels and is looking to diversify. Within the company, the idea was raised that these skills could be applied to ocean racing vessels, a booming sector. It was only natural that Alain de Bergh, the Dassault engineer in charge of structural calculations, contacted Eric Tabarly, THE ocean racing specialist. The invitation to visit the Dassault factories was launched and when Alain de Bergh asked Éric Tabarly what possible uses there might be for him, he naturally replied that this could be applied to the new racing trimaran project he had in mind, a multihull that would use foils. Not to fly, because the slowness of Williwaw, due to its weight and its inexperienced crew, has not yet led it down this path, but simply to relieve the bows and generate performance gains.

1976 Éric Tabarly and Alain de Bergh imagine a multihull with foils

Although Tabarly had a clear vision of what he wanted, he had no plans. So it was that Alain de Bergh began to draw up a project for a hydrofoil trimaran based on his knowledge of aeronautics. The first drawings came out with small foils, in line with Tabarly's wishes. It was the unexpected arrival of Pierre Perrier, the engineer in charge of aerodynamic calculations at Dassault Aviation, that changed all that during a work session: seeing the plans, he suggested that the boat could fly, and quickly calculated new, larger foils that would enable this to happen. Tabarly liked the idea, but had to demonstrate its feasibility. The construction of a 1/3 scale prototype was launched, and in the summer of 1976, Éric Tabarly tried out a flying trimaran prototype built around a Tornado hull by a team from the Civil Engineering Department of the IUT in La Rochelle, led by Jean Garnault, based on calculations made by Professor Li Fang Tsen of the University of Poitiers, which completed the initial project designed by Dassault.

1979 The birth of the Paul Ricard hydrofoil trimaran

The 1/3 size prototype flies well, which confirms the viability of the project. In 1979, the realization of a full-scale trimaran is launched thanks to the arrival of the Paul Ricard company, which will sponsor the project and give its name to the boat to take the start of the Le Point-Europe 1 double-handed transatlantic race which takes place during the year. But the lack of time, the limited budget and the weight of the aluminum, which turns out to be too important compared to the expected level of resistance, will lead to the abandonment of the idea of obtaining a boat which flies and the resumption of the initial concept of relief of the bows. Launched only a few days before the start of the race, the Paul Ricard was not perfected: it finished second in the transatlantic race, just over 5 minutes behind the winner. But it was in 1980, on the way back to France, that he became a legend: he smashed the record for crossing the Atlantic under sail, held for 75 years by skipper Charlie Barr on the schooner Atlantic. For Tabarly, it was confirmation that his intuition was right: foils are an avenue to explore for designing high-performance racing boats.

II: BIRTH AND LIFE OF L'HYDROPTÈRE

1984 the éric tabarly - alain thébault meeting.

In 1984, Éric Tabarly met a young sailor, Alain Thébault. The latter was very interested in the idea of flying a racing boat. Éric Tabarly obtains Alain Thébault's attachment during his military service and the two men begin to work with Alain de Bergh, starting again from the flying option that had to be abandoned for the Paul Ricard. At first, towed models, made by Alain de Bergh's son, Christian, were tested in the grand canal of the Château de Versailles. Then came the radio-controlled models.

1992 French industry mobilizes

In 1987, thanks to financing from Dassault Aviation, a 1/3 scale model in composite materials, including carbon, is built. It took Alain Thébault 4 years, depending on the funding, to perfect it and obtain a stable flight in as many gaits as possible. In June 1991, the 1/3 scale model is exhibited at the Paris Air Show and generates a lot of interest. In August 1992, Eric Tabarly gathered a committee of industrialists and decision-makers at his home in Bénodet and convinced them to embark on the adventure. Dassault Aviation, DCN (Naval Group), Matra, CNES, Dassault Electronique, Chantiers de l'Atlantique, Brochier SA (Hexcel Composites), the Pays de la Loire region and the French Ministry of Research and many others all joined forces to build L'Hydroptère.

1994 The first flight of L'Hydroptère

In September 1994, L'Hydroptère is launched in Saint Nazaire and on October 1st, the first flight is made offshore of Saint Nazaire. She flies well and she flies fast! Too fast, perhaps, compared to the dimensioning of her structure... The more the speed increases, the more the crossbeams and the foils are solicited. The efforts are huge, way beyond our expectations. The first breaks quickly appeared: the rear foil at the end of 1994, then a lateral beam a year later.

2005 Reliability and first record

Aerospatiale (Airbus) joins in the adventure, producing new crossbeams based on the new carbon structural beams used on the A340. New carbon foils on titanium frames are produced. All aluminum fittings are replaced by titanium. In 2004, this system will be completed by force limiters, a kind of shock absorber, derived from the Rafale Marine's landing gear: installed on the strut that holds the lateral foils at 45°C in relation to the crossbeams, they can withstand forces up to 60 tons, thus limiting the risk of breakage. The addition of these aeronautical technologies to L'Hydroptère, which is now even closer to an airplane, enabled it to accelerate and begin to show its potential: on February 9th, 2005, it beat the record for crossing the English Channel in 34 minutes 24 seconds, faster than Blériot and his airplane.

2005 L'Hydroptère saved by a Swiss patron

June 2005, in the middle of a record attempt between Cadiz in Spain and San Salvador in the Bahamas, L'Hydroptère hit a unidentified submerged object (USO) off the Canaries. While the ship was being built in Lanzarote, a major storm hit the Canaries. The storm was so severe that L'Hydroptère, although solidly lashed, broke out of her bows and crashed onto the quay and the rocks, sounding the premature end of the adventure.

While all seemed lost, thousands of kilometers away, in Switzerland, Thierry Lombard, the director of the investment bank Lombard-Odier, decided to save the project and offered help to Alain Thébault and his team. L'Hydroptère was then repatriated to France and a renovation and optimization project was launched.

2006-2011 Hunting for records

In 2006, she is back on the water and the Ecole Polytechnique Fédérale de Lausanne (EPFL) proceeds to the hydrodynamic optimization of her foils, which marks the starting point of a series of records:

On April 4, 2007, L'Hydroptère led by Alain Thébault and his crew broke the absolute sailing speed record with an average speed of 44.81 knots over 500 m and 41.96 knots over 1 nautical mile (1852 m).

In September 2009, L'Hydroptère broke the mythical 50-knot barrier - the equivalent of breaking the sound barrier in aeronautics. Two months later, on November 8th, L'Hydroptère confirmed its status as the world's fastest flying trimaran, with 51.36 knots over 500 m, 50.17 knots over 1 nautical mile and a top speed of 55.5 knots (102.8 km/h).

2012-15 The American Misadventure

In July 2012, L'Hydroptère was transported to California in order to attempt the Los Angeles-Honolulu record, which had been held since 2005 by Olivier de Kersauson on board Geronimo. The attempt will finally take place in June 2015 but the weather window is not good: the record will not be broken. For lack of sponsors and funding, L'Hydroptère will be abandoned in Hawaii shortly after her arrival.

III: L'HYDROPTERE 2.0

2019 L'Hydroptère's last chance

While L'Hydroptère is abandoned at anchor in Keehi Harbor, a marina with a bad reputation next to the Honolulu airport, the state of Hawaii, which wants to clean up its harbors, ended to impound her and put her on auction. The date of the sale is set for June 28, 2019. This sale is the last chance for the ten or so boats in the catalog before certain destruction.

Relayed by the world of ocean racing, L'Hydroptère's auction notice makes the rounds of the internet. Two sailing and technology enthusiasts, one Californian, the other French, heard what could be considered L'Hydroptère's last SOS.

June 2019 Two enthusiasts buy L'Hydroptère

The night before the auction, Chris Welsh and Gabriel Terrasse meet at the Waikiki Yacht Club through trimaran collector Stephen Marcoe. Chris is a businessman and sailor, he has a shipyard in California. Gabriel is not a sailor but have been involved in the 2000s on L'Hydroptere project as webmaster and has a network in France that allows him to find the necessary skills to commission and operate L'Hydroptère. As their profiles are rather complementary, they decide to join forces rather than compete in the auction. And on the fatidic 28th of June at 9:30 am, they became together the new owners of L'Hydroptère.

2019-2023 The rescue of L'Hydroptère and her odyssey from Hawaii to France

While the hull and floats, mast, structure, foils and shock absorbers are all intact, L'Hydroptère was completely stripped of all equipment and fittings during its abandonment: it's an empty shell, and everything has to be rebuilt on board. This will take several months, and on November 2nd, L'Hydroptère sets sail autonomously for Chris Welsh's yard in San Francisco, arriving there 15 days later without a hitch. In 2020, L'Hydroptère is taken out of the water and completely dismantled. In May, contact is made with the Airbus Technocentre in Nantes, which wants to help renovate L'Hydroptère. Airbus logistics mobilized and made its ships available for repatriation, sailing between Alabama and Saint-Nazaire. In 2021, 2 trips will bring all the aeronautical parts of L'Hydroptère (foils, crossbeams, shock absorbers) back to the Technocentre. And in January 2023, the central hull, mast and floats arrive. After an odyssey of 3.5 years and 15,000 km, L'Hydroptère is finally back in France!

2023 the beginning of a new life of innovation for L'Hydroptère

Since its launch, L'Hydroptère has been an experimental sailing yacht that has evolved many times over. So much so that the only 1994 element still on board is the central hull. This constant improvement has enabled L'Hydroptère to break new ground in high-speed sailing, paving the way for modern racing boats, now almost all equipped with foils.

Innovation is the DNA of L'Hydroptère. And it is quite natural that she will continue her life as an experimental R&D platform by welcoming on board innovative projects and allowing them to develop more rapidly. While the quest for speed is no longer a priority, L'Hydroptère will continue to seek efficiency, recyclability, and sustainability in order to help reduce our impact on the environment.

L'Hydroptère still holds the world sailing speed record in category D (more than 27.8 m² of sail area) and remains the fastest ocean-going sailing boat in the world.

CHRIS WELSH L'ESPRIT D'AVENTURE

Copyright L'HYDROPTERE 2.0

The Development of Foiling Sailboats

13 December 2017

Following the recent launch of the new Figaro Beneteau 3 , we take a look at how foiling has become so prominent in our sport. From cruising trimarans to racing catamarans and new offshore monohulls, foiling is taking off in sailing – literally! But how did it all come about? And where is it heading? Here we give you a brief history of the development of foiling sailboats and take a look at some of the most exciting foiling classes on the water today…

Development of Foiling – 100 Years in the Making

Foiling may seem like a recent technological phenomenon but it has actually been 100 years in the making. The first development of a foiling water vessel was a 60hp motorboat designed and built by Italian inventor Enrico Forlanini in 1906. Later, in 1919, Alexander Graham Bell broke the world marine speed record with his Hydrodrome 4.

It wasn’t until the 1960’s and 1970’s that foiling technology was introduced to the military and used commercially with the launch of the Boeing Jetfoil, first serving the Hawaiian Islands and later Hong Kong and Macau.

The first significant development of foiling in the sport of sailing was David Keiper’s foiling trimaran ‘Williwaw’ which cruised many nautical miles around the Pacific. Then, in 1980, Éric Tabarly sailed the foiling trimaran ‘Paul Ricard’ across the Atlantic. Later, at the turn of the millennium, we saw the first signs of foiling sailboats performing well on the race course with the Moth pioneering the concept and first putting it into action.

The Moth class has been key to the development of foiling in monohull sailboats. Most notably, Brett Burvile’s foiling moth was the first model that proved to be very quick on the reaching courses of the Moth Worlds in Perth. Subsequently, the Moth Class committee adjusted the One Hull Rule to encourage the development of foils in this monohull class. What followed was a rapid development of technology within the class to lead it to become one of the leading racing foiling sailboat classes in the world today.

60ft Foiling Monohulls – Vendee Globe

The 2016-2017 Vendée Globe race saw foiling 60 ft single handed boats race non-stop around the world for the first time. This is a huge development in the IMOCA class and foiling is a feature that is set to grow in future editions of this iconic “Everest of the seas” event. With improvements in speed of over several knots downwind, the foiling IMOCA 60’s are performing well on the race track. British sailor, Alex Thomson, came an impressive second overall in the latest race aboard his foiling IMOCA 60, despite damage to one of his foils early on in the race. The other two podium placed IMOCA’s were also foiling boats and a new race record was set by winner, Armel Cléac’h, fueling the idea that foiling Open 60s may be here to stay.

Figaro Beneteau 3

The first production foiling one-design monohull, the  Figaro Beneteau 3 , is big news in the world of foiling sailboats. Created through a collaboration of Groupe Beneteau’s expert design team and winning Vendée Globe boat architects Van Peteghem Lauriot-Prévost (VPLP), the Figaro Beneteau 3 is certainly turning heads. The foils have an inward-facing profile to reduce drift and improve righting moment, thus increasing performance. This new model is expected to be as much as 15% faster than its predecessor, so is set to be a significant turning point for the class. With a prototype launched this summer, the new design is already receiving great reviews and is expected to be on the startline of the 50th edition of the Solitaire in 2019.

Foiling Multihulls

America’s cup ac72, ac50 and ac45.

Some of the most noteworthy racing foiling catamarans in recent years have to be those from the 2013 and 2017 America’s Cups. The AC72’s proved that large format foiling catamarans could be raced at extreme speeds and on tight courses, making for a challenging event for the crews and exciting spectacle for fans. This concept was further developed for the 2017 America’s Cup with the AC50s and the Youth America’s Cup in the AC45s. The introduction of foils into this pinnacle sailing event has seen speeds accelerate phenomenally, resulting in high octane racing on the water. The America’s Cup Teams have also invested significant amounts of money into research and development of foiling technology, the results of which are likely to trickle down and raise the bar for other foiling classes as a whole.

The GC32 is a 10m long by 6m wide foiling catamaran created through the collaboration of Laurent Lenne, Dr Martin Fischer, Head of Design at the Groupama Team France America’s Cup team, and Premier Composite Technologies. Fitted with T-foil rudders and J-shaped daggerboards, the GC32 can reach speeds of up to 40 knots. But with no hydraulics, no pedestals and a more manageable, easier to trim soft-sail rig, the GC32 is designed to be more accessible than some of the larger foiling multihulls on the water. The Extreme Sailing Series and GC32 Racing Tour are the pinnacle events for the class, attracting both pro-am and commercial teams, from all over the world, who want to get involved with the fast paced sailing action.

After making its first appearance at the Olympic Games in 2016, the Nacra 17 has been developed to incorporate curved foiling daggerboards for extra lift and speed. The first Nacra 17 World Championship with the new foiling configuration took place in France in September this year with a view to the Foiling Nacra 17 competing at the Olympic Games Tokyo in 2020. This will be the first time that foiling sailboats will appear at the Olympics so will be a huge milestone for foiling multihull dinghy sailing.

Foiling Future

What the future of foiling sailboats looks like is unknown, but what seems clear is that it is a format that is providing lots of fun and excitement for many sailors and is probably here to stay. With foiling playing a pinnacle role at high profile sailing contests such as the Vendée Globe, Solitaire, America’s Cup and the Olympics, it is an aspect of the sport that will continue to grow and the advancing technology that is arising from the research and development made by the big race teams will probably trickle down into more accessible and affordable formats for mainstream sailing. There is certainly a place for both foiling and non-foiling boats on the market and we look forward to seeing how this new aspect of our sport develops in years to come.

Quick Q&A with Land Rover BAR Academy Skipper Rob Bunce

What was it like to sail a foiling boat for the first time.

Pretty scary to start with. The noise is the first thing that gets you and the acceleration is like no other boat I have sailed. It was pretty difficult to keep the grin off my face.

What do you enjoy most about racing foiling boats?

The intensity of the racing is fantastic. With just one gust you could foil past everyone, so the fleet stays very tight. The reaching starts create some incredible close racing at speeds in excess of 30 knots with the boats only inches from each other at times.

Foiling boats are much quicker than non-foiling boats and on the AC45 and GC32 you are on a very small racetrack - how have you had to adapt your skills to race at such fast speeds?

The boats are certainly very physical and when you throw in a short course there are lots of manoeuvres with no time to catch your breath in between. Every sailor has to be on top of their game from a fitness point of view. With each position onboard posing a slightly different physical challenge it’s key to be very specific with your training so you become the best in your area. It’s also important to analyse all of the boat-handling skills and realise that grunt isn’t always the solution. The best sailors on these fast boats are the most efficient, not necessarily the outright strongest.

Rob Bunce is Skipper for the Land Rover BAR Academy. The team won the Red Bull Youth America’s Cup this year and are currently competing in the Extreme Sailing Series .

Share this story

Lost Password?

Don't have an account? Register

We and our {{count}} partners use cookies and other tracking technologies to improve your experience on our website. We may store and/or access information on a device and process personal data, such as your IP address and browsing data, for personalised advertising and content, advertising and content measurement, audience research and services development. Additionally, we may utilize precise geolocation data and identification through device scanning.

Please note that your consent will be valid across all our subdomains. You can change or withdraw your consent at any time by clicking the “Consent Preferences” button at the bottom of your screen. We respect your choices and are committed to providing you with a transparent and secure browsing experience.

Privacy Overview

• Most purposes explained in this notice rely on the storage or accessing of information from your device when you use an app or visit a website. For example, a vendor or publisher might need to store a cookie on your device during your first visit on a website, to be able to recognise your device during your next visits (by accessing this cookie each time).
• A car manufacturer wants to promote its electric vehicles to environmentally conscious users living in the city after office hours. The advertising is presented on a page with related content (such as an article on climate change actions) after 6:30 p.m. to users whose non-precise location suggests that they are in an urban zone.
• A large producer of watercolour paints wants to carry out an online advertising campaign for its latest watercolour range, diversifying its audience to reach as many amateur and professional artists as possible and avoiding showing the ad next to mismatched content (for instance, articles about how to paint your house). The number of times that the ad has been presented to you is detected and limited, to avoid presenting it too often.
• If you read several articles about the best bike accessories to buy, this information could be used to create a profile about your interest in bike accessories. Such a profile may be used or improved later on, on the same or a different website or app to present you with advertising for a particular bike accessory brand. If you also look at a configurator for a vehicle on a luxury car manufacturer website, this information could be combined with your interest in bikes to refine your profile and make an assumption that you are interested in luxury cycling gear.
• An apparel company wishes to promote its new line of high-end baby clothes. It gets in touch with an agency that has a network of clients with high income customers (such as high-end supermarkets) and asks the agency to create profiles of young parents or couples who can be assumed to be wealthy and to have a new child, so that these can later be used to present advertising within partner apps based on those profiles.
• An online retailer wants to advertise a limited sale on running shoes. It wants to target advertising to users who previously looked at running shoes on its mobile app. Tracking technologies might be used to recognise that you have previously used the mobile app to consult running shoes, in order to present you with the corresponding advertisement on the app.
• A profile created for personalised advertising in relation to a person having searched for bike accessories on a website can be used to present the relevant advertisement for bike accessories on a mobile app of another organisation.
• You read several articles on how to build a treehouse on a social media platform. This information might be added to a profile to mark your interest in content related to outdoors as well as do-it-yourself guides (with the objective of allowing the personalisation of content, so that for example you are presented with more blog posts and articles on treehouses and wood cabins in the future).
• You have viewed three videos on space exploration across different TV apps. An unrelated news platform with which you have had no contact builds a profile based on that viewing behaviour, marking space exploration as a topic of possible interest for other videos.
• You read articles on vegetarian food on a social media platform and then use the cooking app of an unrelated company. The profile built about you on the social media platform will be used to present you vegetarian recipes on the welcome screen of the cooking app.
• You have viewed three videos about rowing across different websites. An unrelated video sharing platform will recommend five other videos on rowing that may be of interest to you when you use your TV app, based on a profile built about you when you visited those different websites to watch online videos.
• You have clicked on an advertisement about a “black Friday” discount by an online shop on the website of a publisher and purchased a product. Your click will be linked to this purchase. Your interaction and that of other users will be measured to know how many clicks on the ad led to a purchase.
• You are one of very few to have clicked on an advertisement about an “international appreciation day” discount by an online gift shop within the app of a publisher. The publisher wants to have reports to understand how often a specific ad placement within the app, and notably the “international appreciation day” ad, has been viewed or clicked by you and other users, in order to help the publisher and its partners (such as agencies) optimise ad placements.
• You have read a blog post about hiking on a mobile app of a publisher and followed a link to a recommended and related post. Your interactions will be recorded as showing that the initial hiking post was useful to you and that it was successful in interesting you in the related post. This will be measured to know whether to produce more posts on hiking in the future and where to place them on the home screen of the mobile app.
• You were presented a video on fashion trends, but you and several other users stopped watching after 30 seconds. This information is then used to evaluate the right length of future videos on fashion trends.
• The owner of an online bookstore wants commercial reporting showing the proportion of visitors who consulted and left its site without buying, or consulted and bought the last celebrity autobiography of the month, as well as the average age and the male/female distribution of each category. Data relating to your navigation on its site and to your personal characteristics is then used and combined with other such data to produce these statistics.
• An advertiser wants to better understand the type of audience interacting with its adverts. It calls upon a research institute to compare the characteristics of users who interacted with the ad with typical attributes of users of similar platforms, across different devices. This comparison reveals to the advertiser that its ad audience is mainly accessing the adverts through mobile devices and is likely in the 45-60 age range.
• A technology platform working with a social media provider notices a growth in mobile app users, and sees based on their profiles that many of them are connecting through mobile connections. It uses a new technology to deliver ads that are formatted for mobile devices and that are low-bandwidth, to improve their performance.
• An advertiser is looking for a way to display ads on a new type of consumer device. It collects information regarding the way users interact with this new kind of device to determine whether it can build a new mechanism for displaying advertising on this type of device.
• A travel magazine has published an article on its website about the new online courses proposed by a language school, to improve travelling experiences abroad. The school’s blog posts are inserted directly at the bottom of the page, and selected on the basis of your non-precise location (for instance, blog posts explaining the course curriculum for different languages than the language of the country you are situated in).
• A sports news mobile app has started a new section of articles covering the most recent football games. Each article includes videos hosted by a separate streaming platform showcasing the highlights of each match. If you fast-forward a video, this information may be used to select a shorter video to play next.
• An advertising intermediary delivers ads from various advertisers to its network of partnering websites. It notices a large increase in clicks on ads relating to one advertiser, and uses data regarding the source of the clicks to determine that 80% of the clicks come from bots rather than humans.
• Clicking on a link in an article might normally send you to another page or part of the article. To achieve this, 1°) your browser sends a request to a server linked to the website, 2°) the server answers back (“here is the article you asked for”), using technical information automatically included in the request sent by your device, to properly display the information / images that are part of the article you asked for. Technically, such exchange of information is necessary to deliver the content that appears on your screen.
• When you visit a website and are offered a choice between consenting to the use of profiles for personalised advertising or not consenting, the choice you make is saved and made available to advertising providers, so that advertising presented to you respects that choice.

Yachting World

• Digital Edition

The foiling phenomenon – how sailing boats got up on foils to go ever-faster

• Matthew Sheahan
• July 20, 2015

The biggest revolution to hit watersports has been foiling, but how did it start and what are the issues involved? Matthew Sheahan investigates

Here’s a challenge. Design a way to support the weight of five saloon cars on a plate the size of your desk on the water. That was the task that faced America’s Cup designers in their bid to make the new breed of foiling America’s Cup boats fly.

If that’s a bit tough, here’s an alternative. Support a 70kg person and their boat in the water on a plank the size of a cricket bat. This one is much easier, the GCSE of hydrodynamics by comparison, with plenty of examples as to how it can be done thanks to the proliferation of foiling Moths around the world.

Getting boats to fly above the water surface is simple in theory, but tricky in practice and has challenged designers for over a century, but in the last decade one class appears to have cracked it.

On the face of it, International Moths on hydrofoils are sailing’s answer to the unicycle. But Moth sailors are far from being trick cyclists, there is a serious side to all this. A foiling Moth will reach 14 knots upwind and 20 knots downwind in just ten knots of wind, and in 20 knots of breeze they’ll be cranking along at 17 knots upwind and 25-30 knots down.

The International Moth has done more than any class to raise the profile of sailing hydrofoils. Photo: Thierry Martinez/Sea&Co

Whether you’ve seen the pictures or experienced the ghost-like whistle followed by the eerie vacuum that trails behind as they come slicing past, it is clear the Moth fleet has done much to publicise the thrill, grace and speed of sailing hydrofoils. The rapid growth of the class has also shown us that foiling is not just for pioneers and record breakers, but that despite several failed attempts in the past to bring it to the masses, this time there just might be a future in foiling.

Another reason why this particular class has exerted so much influence in sailing and spawned a new cycle of design is that Moths can race as a fleet round a course, foiling upwind and down. Although there are plenty of other boats that foil, most have a limited sailing repertoire and need specific conditions to fly. A Moth can fly on all points of sail and is capable of tacking and gybing too.

This has been one of the biggest steps forwards and has helped to boost recent interest from designers and sailors for other potential foiling projects.

Foiling, it’s a drag

At high speed, drag and seakeeping become big issues aboard any vessel, particularly offshore monohulls, and while yacht design has made some big steps forward since the days of hauling half the ocean behind in a pair of breaking quarter waves, there are other issues holding back performance.

Razor-straight wakes ironed flat by beamy after sections are clearly a step forward. Yet the problem for monohulls is that, as they slam and crash their way into the waves, keeping the structure in one piece is a big challenge. Rising above the water’s surface not only reduces drag, but might help to reduce structural risks and make handling at speed easier.

Typical resistance curve showing the rapid reduction in drag once a vessel gets airborne

Forty years ago it looked as though offshore foiling was about to make a breakthrough. David Keiper took the concept cruising in the 1970s with his trimaran Williwaw (see below), in which he clocked up a staggering 20,000 miles cruising the South Pacific. A decade later, French sailing legend Eric Tabarly broke the schooner Atlantic’s west to east transatlantic record set by Charlie Barr in his foiling trimaran Paul-Ricard.

Yet despite such feats, offshore foiling stalled. Tripping up at speed and keeping the boat in one piece when it touches back down have been the main concerns. And while neither of these two pioneers suffered such a fate, there are plenty of wince-inducing reminders of how it can all go pear-shaped.

But today foiling is more popular than ever. The French tri-foiler and former world record holder L’Hydroptère was the first sailing boat to break through the 50-knot barrier. Since then, a new world record has been set by Paul Larsen’s Sailrocket, another foiler, albeit an extreme one, which owes its success to a recent breakthrough in hydrodynamics.

L’Hydroptère, former speed record holder. Photo: Christophe Launay

Both share a longer-term view of taking foiling offshore. So does the British foiling cat project C-Fly with its canard configuration.

Meanwhile, the America’s Cup cats are trying to scorch around an inshore racecourse on foils that have no moving control surfaces. It’s a big ask of a high-speed boat and there have been spectacular crashes.

Then there’s SYZ&Co, the 35ft foiling cat on Lake Geneva, the new L’Hydroptère.ch, as well as the hull-less Mirabaud LX. These are just a few of the better known foiling projects, but plenty of others are experimenting with hydrofoils in subtler, more discreet ways – and not just racers and record-breakers.

Foils not just for the few

Cruising catamaran manufacturers Catana launched a 59ft luxury cruising cat that has curved daggerboards that the builders claim produce half a tonne of lift at ten knots. The Dynamic Stability System (DSS), which uses a hydrofoil in the horizontal plane, doesn’t aim to raise the boat out of the water, but instead uses hydrodynamic lift to improve its performance – although the new Quant 23, claimed to be the first foiling keelboat, uses the DSS is a new and thrilling way.

Quant 23, claimed to be the first foiling keelboat

And then there are those who seek to bring the thrills of hydrofoils to the average sailor. In quick succession there have been a couple of 36ft Infiniti multihulls, the Flying Phantom, the Gunboat foiling 40ft G4 and the Formula Whisper foiling catamaran, possibly the first foiler designed for club sailors. There has even been a first Foiling Week in July 2014, where a number of different foiling boats strutted their stuff.

Foiling is in vogue and capturing people’s imagination. But apart from the Moth sensation, why is foiling so popular now and where is this all leading?

Material advances

As is so often the case, the answer lies in the development of new materials and techniques. Weight and strength is at the heart of the issue and carbon has once again played a big part.

While foiling clearly appears to reduce the wave-making drag considerably, there is no free lunch. Lift and drag go hand in hand and what happens beneath the surface can sometimes wipe out any benefit above. For example, tilting a foil at a large angle of attack may create lift, but there will often be a large amount of drag too.

“You don’t fly for the beauty of it,” says aeronautical engineer Joseph Ozanne, Oracle’s lead wing designer for the two previous America’s Cup cycles. “People forget that to generate sufficient lift to raise an entire boat can mean introducing a lot of drag. Just because you’re flying doesn’t mean you’re suddenly more efficient or faster.”

Josephe Ozanne, who worked for Oracle duing the last two America’s Cups

To test this, put your hand horizontally outside a car window while it’s going along and rotate it gradually. Initially, with a small angle of attack, your hand will want to rise, but as you twist your palm further, the force pulling it backwards increases significantly.

It’s the same with foils; you can generate lift at high angles of attack, but you won’t necessarily be going any quicker simply because you’ve lifted out of the water.

30kg all up

As a generalisation, less weight means less vertical force is required, which means small angles of attack, which in turn means low drag. From here it’s easy to see how modern materials and the dramatic reduction in the all-up weight of modern boats has helped to make hydrofoils more feasible. Taken to extremes, a modern Moth weighs just 30kg all-up, less than half the weight of its crew.

But the theory doesn’t work for all lightweight, powerful boats; there is a limit.

“Back in 2006 when we were designing Mike Golding’s Gamesa, we looked into the possibility of a fully foiling Open 60,” reveals designer Merfyn Owen. “An Open 60 is a pretty powerful boat and when you compare the sail area:displacement ratio with that of a Moth there appears to be evidence that a foiling 60 could work.

“The trouble is that, unlike a dinghy where the crew generates huge righting moment when compared to the weight of the boat by sitting it out, on an Open 60 the rules on stability prevent you from generating enough righting moment to get the boat fully up on its foils. The Open 60 also has a wide draggy hull compared with a Moth with lots of wetted surface area that holds you back.”

So if an Open 60 would struggle to get up, the prospect for other large foiling monohull keelboats is looking doubtful.

SYZ&Co cants its daggerboards to vary the amount of side force and vertical lift

Multihulls, on the other hand, are lighter for the same length and sail area and can generate huge amounts of righting moment without putting on weight, thanks to their wide beam. This makes them better suited to hydrofoils. But there are other problems to overcome and several key configurations to consider.

Foiling configurations

The first issue is how much foil surface area you need to lift the boat. This varies with speed: the faster you go, the less you need. Early foil design used ladder-type racks of foils which lifted out of the water as the boat went faster, reducing the number of immersed foils as the speed increased. But this comes with a big drag penalty at slow speeds.

Surface-piercing configurations, where the foils are angled in a V shape, also find their own natural ride height depending on the speed. As the boat accelerates, the foils generate more lift, raising the boat, which in turn reduces the amount of foil in the water until equilibrium is achieved. The boat finds its own ride height automatically, with no moving parts required.

The configuration works in a similar manner with heel. As the boat heels to one side, more foil is immersed on the leeward side – and less to windward – which helps to right the boat. This inherent stability makes the surface-piercing configuration a popular one – it can be seen on boats like L’Hydroptère . But the problem comes at slow speeds when the high drag of the fully immersed foils hampers performance.

Fully submerged foils, where the lifting part of the arrangement is a horizontal foil mounted under the water at the bottom of a vertical strut, offer the lowest drag, but they have to incorporate an additional element to control the ride height. In other words, the foil has to change its lift characteristics depending on speed.

To do this, the horizontal foil has a moving element on its trailing edge like an aircraft’s elevator. In the case of the Moth, this elevator is connected mechanically to a ride height sensor, a wand that skims across the water’s surface. The lower the boat is travelling above the water, the more the elevator is deployed, creating more lift. But as the boat accelerates the lift increases and it starts to rise. The wand then takes up a different angle from the water’s surface and reduces the deflection of the elevator, reducing the lift.

Apart from the difficulty of following the sea’s surface in big waves, the problem for most sailing boats, especially keelboats, is that this configuration doesn’t provide any athwartships stability. The Moth stays upright because its crew hikes to windward. The same is true for other dinghies and cats that use crew weight for righting moment. On monohulls it’s difficult to make the configuration work.

‘C’, ‘L’ and ‘S’ foils

But not everyone wants to fly. In recent years there has been a great deal of development in foils with complex shapes from ‘C’ shapes, to ‘L’ and ‘S’ shapes and now ‘S’ foils with winglets. Generally speaking, these foils are less concerned with flying and more with the balance between generating sideways lift to drive you upwind and vertical lift to reduce displacement. Much of this development work took place in the former ORMA 60 multihulls.

“By canting the leeward daggerboard you can change the balance between lateral and vertical lift,” explains Vincent Lauriot-Prévost of designers VPLP, experts in high-performance multihulls and some of the world’s more extreme designs such as USA-17 and L’Hydroptère.

“When you’re sailing upwind, side force from the daggerboard is very important, as it is in any boat, but as you sail freer and faster you need less foil to create the required side force. Normally you would lift the board to reduce the drag, but if you leave it down and then cant it in towards the centreline, you create some vertical lift which then helps to reduce the displacement of the boat.

“Another way to achieve a similar effect is to have a curved daggerboard. A simple ‘C’ shape provides more vertical lift the further it is pushed down. The next stage of development was then to try ‘S’ shaped boards which, again, vary the distribution of lift and side force depending on where the boards are set.”

Although more expensive to build than straight boards, curved daggerboards have the advantage that they do not need complex canting mechanisms. Some classes and rules ban the latter so this is an alternative approach.

“Our ORMA 60 design Gitana II, which won the Route du Rhum in 2006, would see a reduction in displacement of 40 per cent at 20 knots,” says Lauriot Prévost. “At 26-28 knots the displacement would reduce to 70-75 per cent for a boat that weighs 6.5 tonnes fully loaded.”

This puts the issue of displacement reduction into perspective for cruising boats. Half a tonne of lift at ten knots from a curved daggerboard might sound a lot, but when the boat displaces 22 tonnes loaded, the displacement reduction is just over two per cent. While this may still have a beneficial effect on performance, it becomes easier to see that the future for cruising hydrofoils is not so clear cut.

Changes to trim, stability and displacement through subtle alterations in the alignment of foils is also a growing trend in the Open 60s and now the Volvo 65. Angling the keel pin up at its forward end by a few degrees provides a positive angle of attack on the keel fin when canted out to windward. When swung out to one side, the fin acts like an aircraft’s wing and helps to support the boat, although the lift also tends to reduce the effective righting moment.

Nevertheless, according to at least one top designer, the effort is worth it. He says: “There are some other performance details involved with this that I can’t speak about!”

Foils of the future

Where is the current craving for foils taking us? One of the biggest foiling experiments at present is in the America’s Cup. With their notoriously big budgets, Cup campaigns are well-known to accelerate the development of ideas that can eventually trickle down. What kind of technology breakthrough will wingmasted cats on foils provide?

The answer is not a simple one as the AC72s used in the 2013 Cup were never originally intended to foil. A loophole in the rule, exploited by the New Zealand team and deemed legal by the jury, sent teams off exploring the possibilities, but with little scope to control the foils themselves as no moving parts are allowed.

In the 2013 America’s Cup, the Kiwis exploited a loophole in the rule to put their catamaran on foils

“The Kiwis look good on foils, they are stable in pitch and heave and their foils appear to be reliable. But this will all come at a cost: drag,” said Oracle’s Joseph Ozanne at the time. “Less pitch stability, as our boats had, can reduce drag, but it makes the boat very tricky to sail. We did a lot of wheelies when we were learning to sail our boat. Regulating flight height is a nightmare.

“Modern aircraft are designed to be more unstable to improve manoeuvrability and also to reduce drag, but they have systems that keep them under control. We are not allowed these systems, so it’s the crew that have the control. So the key foiling lessons from the Cup could be learning about foil shapes and how to handle instability.”

For Sailrocket II’s foil designer Chris Hornzee-Jones, another aeronautical engineer, hydrofoiling means speed. Having set a new world record at 64.54 knots and broken into new territory, Hornzee-Jones believes this is just the beginning.

Chris Hornzee-Jones, Sailrocket’s foil designer

“I’m convinced we can get to 70-75 knots with subtle developments to this foil,” he declares. “Beyond that it becomes progressively harder, but the fact that powered craft on foils have achieved 80-100 knots confirms that there are foil shapes that will work at this speed. I think it may be difficult to get a single foil to perform over the entire speed range. We already use two on Sailrocket. Nevertheless, I do see over 80 knots as possible.”

The lessons learnt in this new speed territory could also have implications at far slower speeds and for much less extreme boats.

“Thick foils like the one we developed are good structurally,” says Hornzee-Jones. “Creating a foil that ventilates at low speeds means that at, say, 20 knots you are already into low drag.”

Like a gearbox and engine combination that allows you to engage top gear at 20mph and accelerate though to 100mph without changing gear, versatile, vice-less foils could indeed transform the behaviour of our boats in the future. Add to that the possibility of active control using sophisticated, compact and efficient electronics and new possibilities emerge.

Opening our minds

Although the average cruising monohull may not want to get up and flying, efficient low-drag stabiliser foils, for example, controlled by a tiny chip, could make the notoriously rolly tradewind conditions on a transatlantic a more comfortable and efficient affair.

Vincent Lauriot-Prévost

“Foiling Moths have opened people’s minds,” says Vincent Lauriot-Prévost. “The future will depend on having good control of efficient foils. We will need to change camber profiles effectively and develop automatic trim regulation. But, we must also think weight, otherwise the systems won’t work.”

Perhaps it is no surprise that after more than 70 years of sailing development at the leading edge of the sport, many are still scratching their heads at how to make such a promising concept work for the rest of us.

If you enjoyed this….

Yachting World is the world’s leading magazine for bluewater cruisers and offshore sailors. Every month we have inspirational adventures and practical features to help you realise your sailing dreams. Build your knowledge with a subscription delivered to your door. See our latest offers and save at least 30% off the cover price.

• Event calendar
• Miami International Boat Show
• Oceanis 30.1
• Oceanis 34.1
• Oceanis 37.1
• Oceanis 40.1
• Oceanis 46.1
• Oceanis 51.1
• Oceanis Yacht 54
• Oceanis Yacht 60
• FIGARO BENETEAU 3
• Heritage Sailing Yacht
• Flyer 7 SUNdeck
• Flyer 7 SPACEdeck
• Flyer 8 SUNdeck
• Flyer 8 SPACEdeck
• Flyer 9 SUNdeck
• Flyer 9 SPACEdeck
• Antares 7 Fishing
• Antares 8 Fishing
• ANTARES 11 FLY
• Gran Turismo 32
• Gran Turismo 36
• Gran Turismo 41
• Gran Turismo 45
• Swift Trawler 35
• Swift trawler 41 Sedan
• Swift trawler 41 Fly
• Swift Trawler 48
• Swift Trawler 54
• Grand Trawler 62
• Heritage Powerboats
• Future Owners
• A REMARKABLE ANNIVERSARY
• Our History
• Our Architects and Designers
• Our philosophy
• Our Innovations
• Your way to ownership
• Tests and Awards

The foils of the FIGARO BENETEAU 3

At some speeds foils reduce the boat’s weight under sail by nearly 30% in relation to a Figaro BENETEAU 2. 

Production built for the first time to fit out the new  Figaro BENETEAU 3,  foils improve the performance of the Solitaire Urgo Le Figaro one design, by increasing its power and stability at more points of sail, while reducing the effect of drag.

40 YEARS OF PROGRESS

The first attempts at fitting out offshore  racing boats with foils  dates back to the 1970s, with Paul Ricard, Eric Tabarly’s trimaran. At the time, the concept was developed on the Formule 40, equipped with straight foils angled at 45 degrees. Then they were adapted with a curved version on ocean-going trimarans.

There was a major development in 1994, when the Hydroptère was launched. It sailed airborne on three foils at 45 degrees and had a T-rudder. Its success was confirmed in the America’s Cup in 2010, when USA 17 was equipped with J-shaped foils. Then in 2013, the AC72 raced on L-shaped foils at over  40 knots . Shortly afterwards, the Imoca monohulls of the Vendée Globe and then the Ultimes maxi-trimarans and the Multi50s converted to foils.

THE FIRST PRODUCTION FOIL ON A RACING BOAT

BENETEAU has broken new ground by being the first boatyard to install foils on a production offshore racing boat. To build the Figaro BENETEAU 3, they set up a dedicated production site at Cheviré, near Nantes.

“ This project is a real industrial challenge, because foils were a complete unknown to us” , said  Marc Vaillier , in charge of the programme at BENETEAU

“CHISTERA” GLOVE GEOMETRY

The  Figaro BENETEAU 3   foils were produced by Multiplast, each weighing  38 kilos  for a full length of  3.3 metres . Their “chistera” glove shape prevents leeway when close-hauled, assisting the keel fin, of limited width. Their geometry also reduces the drag of the hull and the appendages. 

“TURBO EFFECT”: FASTER AND GREATER STABILITY

In more points of sail, such as reaching and downwind, the Figaro BENETEAU 3’s foils create vertical lift, which takes the strain off the boat and increasing righting moment.

"Instead of making her heavier with ballast windward, we decided to make her lighter downwind by opting for foils”, said Vincent Lauriot-Prévost,  who runs the VPLP design office that designed the Figaro BENETEAU 3.  

The result is higher speed averages and a more stable boat that is roughly 30% lighter than the Figaro BENETEAU 2. With her “turbo effect”, racers can push her harder, particularly in a breeze.

YouTube is deactivated.

To view this video, you must first authorise the use of functionality cookies on our site.

Select your area and your language

• Chinese, Simplified