L'Hydroptere

We look at the world's fastest boat and speak to its creator, Alain Thébault

Finally last week we achieved something we’ve been attempting to get around to for at least a decade... we went sailing on L’Hydroptere and met its amiable creator, Alain Thébault.

On 4 September last year the French foiling trimaran achieved its objective of becoming the world’s fastest boat when it averaged 51.36 knots over a 500m course, beating the previous record of kiteboarder Alexandre Caizergues, who had managed 50.57.

Incredibly this achievement came about after 35 years of long hard work, from getting Eric Tabarly involved (like Michel Desjoyeaux and Roland Jourdain, Thébault sailed with Tabarly on Cote d’Or, although not on the Whitbread) – back in 1975, to building a one third scale model in the late 1980s to the launch of the first iteration of the full sized L’Hydroptere in October 1994. Over the intervening 16 years, since her first launch, L’Hydroptere has endured a number of catastrophic breakages, but with impressive determination Thébault has always bounced back.

“The first step was the effort, like 100 years ago in the transition from balloons and aircraft. They crashed all the time. Now we have an aircraft,” he says of L’Hydroptere. Unfortunately in the early days the learning was empirical and he gives the example of the foils, which when they started out they estimated would be seeing 10 tonnes/sqm whereas expensive trial and error has proved that in reality it is 20 tonnes/sqm.

Throughout this period Thébault has relied heavily on the experience of several grandees of French aerospace engineering – ‘Les Papés’ as they are known, four from Airbus and four from Dassault.

In terms of her overall concept, L’Hydroptere remains similar to how she was originally conceived – a trimaran foiler, sort of fitting into the ORMA 60 rule with an LOA of 18.28m (60ft) but with a beam of 24 (78ft). Her main hull is even narrower than a 60ft tri’s with a step running along its entire length.

Her floats are tiny in comparison and are simply used to stabilise the boat before she gets airborne. However the stumpy floats feature a step, as used on powerboat, sea planes and also Yves Parlier’s 60ft catamaran Mediatis Region Aquitaine. Not immediately evident when you are on board, but there is plumbing so that 1 tonne of water ballast can be pumped up into her weather float.

The impressive bits are of course her foils. The rudder is fitted with a T-foil with an adjustable trim tab to alter the overall pitch of the boat, operated by a simple up/down lever by the steering position. The 5.7m long main lifting foils are mounted just inboard of the floats and like ORMA 60 foils they conclude with a small vertical hook, to give an end plate effect (similar to some aircraft wings) and there are several gates up the length of the foil. The angle of elevation of the main lifting foils has three settings that can be adjusted in fine increments.

To counter the vertical loads there is an additional vertical member and a significant feature of this (that was added in 2004) is a shock absorber system. “I asked a friend working in Airbus, because the design is like the landing gear of an aircraft,” explains Thébault.” When the pressure is over 30 tonnes it releases automatically. So as on the first car, we used to break all the time because we didn’t have this piece. When you sail at 35 knots in big waves, the shock loads...”

Following her frequent breakages, Thébault reckons about 80% of the boat has been replaced in L’Hydroptere’s 16 years of existence (the remaining 20% being her main hull). Nonetheless her weight is still around 6.5 tonnes, around the same as the ORMA 60s built at that time.

When up on her foils, Thébault says there is only around 2sqm of foil area in the water. “When you are over 50 knots, 80% of drag is in the water. We have 1sqm on T-foil [rudder] and 1sqm on the main foil but it is 80% of the drag.”

Typically the main working foils are the rudder T-foil and the leeward lifting foil and the tip of the weather foil. However we understand from the crew that to achieve 50 knot warp factor it is necessary to get the weather foil out of the water and with the boat resting on just her leeward foil and rudder that is when they consider themselves to be ‘the danger zone’.

Unlike ORMA 60 tris, but like several tris that were built in the 1980s, L’Hydroptere uses a single beam configuration, although there is a wide aft beam for the main sheet track, also providing a useful area of trampoline to be fixed in between, allowing the crew to move across the boat quickly. For while ORMA 60s have twin steering consoles mounted at the apex of each side of the aft beam, L’Hydroptere has two fully equipped cockpits on her beam and there is a good 18m bounce across the trampoline and central hull to get from one cockpit to the other.

There is a small cockpit in the centre hull, pretty much only for the runners, everything else is carried out from the cockpits on the beam. Each of these features a seat for the helmsman and a truck-style steering wheel (originally Thébault says they had the wooden wheel from a Jaguar car, but it was too slippery when wet). The main sheet is driven by a pedestal hooked up to a rotary hydraulic pump, operating a giant ram slung beneath the boom, with a release button for the hydraulics under the helmsman’s foot. The principal ‘accelerator’ is the traveller operated from the winch outboard of the helmsman while the headsails are cross-sheeted via a turning block on the middle of the deck, aft of the mast, back to a primary inboard of the helmsman. This set-up is duplicated in both cockpits.

The rig is conventional ORMA 60 with a rotating wingmast and two roller furling headsails on locks, however at 23m is substially shorter than the 30m ORMA 60 masts and she carries a fraction of the sail area with a 195sqm main and 105sqm solent. Since this boat is unlikely to be competing in the Route du Rhum (Thébault says he’d like to, but his family and other team members would leave him), there is no need for halyards to run back to the cockpit so these are all operated from the mast.

The most important structural area after the lifting foils is the main cross beam and this single beam is based around two substantial structural members linked for example where the shock absorber attaches to the beam. The greatest area of load on the boat, according to Thébault, is the beam-hull joint which can see in the order of 60-70 tonnes.

Sailing L’Hydroptere

Being in the fortune position of having sailed on board Groupama 3 and the Banque Populaire maxi-tris, the sensation of sailing L’Hydroptere holds many similarities. The performance is very similar – the speedo regularly leaps around in five knot increments, something you don’t often see on monohulls. There is the potential for sizable G-forces and above 30 knots you really have to hang on.

Once up on the foils (at around 12 knots of boat speed) and up into the 20s and 30s knots of boat speed you experience the same gale force of apparent wind. Communication is hard due to the distance between the cockpit in the main hull and the working cockpit to weather, so this is entirely done on hand signals.

The main difference is in the ride. Something we have noticed before sailing on boats with lifting foils – including the Hugh Welbourn Dynamic Stability Systems boat – is that the foils not only develop lift, but feel like they are pinning the boat to the water, so pitching is drastically reduced. On a foiler this is necessary to prevent the angle of incidence of the foils from altering greatly.

In addition, the foils kick up a lot more wake than conventional racing multihulls where the wake is relatively clean. Saying this even hitting 36 knots as we did, admittedly in the flat water of the Solent, we were dry in the weather cockpit and only caught a little spray in the aft cockpit.

While typically conventional multihulls have a relatively linear performance curve, according to how much traveller you pull on say, with L’Hydroptere this is not the case as there is a hump until the boat gets airborne after which the power is eased off and trimming is done to keep the boat up on her foils.

It should be noted that when L’Hydroptere broke the world speed record last year, she was already 15 years old (or parts of her...) However a distinct difference between her and her newer brethren is that Thébault and his crew (that has in the past included the likes of Eric Tabarly, Jean le Cam and Michel Desjoyeaux, and now includes eight time round the world sailor Jacques Vincent) is supremely confident in their boat and knowing its limitations. Typically they sail with five but for records they usually have 10-11 crew on board.

While the boat is bristling with electronics, including the Cosworth Research Pi data logging system, Thébault is quite old school in terms of driving the boat by gut instinct and feel instead of the displays. “The instrumentation is late all the time,” as he puts it.

This year is one of transition for the team. The original L’Hydroptere we sailed is doing a small tour of Europe and was passing through Cowes en route to Kielerwoche where a German TV station is to make a film about her. However delayed from leaving last weekend by the weather, Thébault took the opportunity to have a crack at PlayStation’s record for sailing around the Isle of Wight. According to Helena Darvelid, who was on board at the time, they did two laps on Saturday – the first took three hours and on the second they were short of PlayStation’s 2 hours 33 minutes record time by just eight minutes and all that achieved in a top wind speed of 19 knots. Think about that when you’re going around this Saturday...

The future

While L’Hydroptere is effectively showponying this summer, ultimately ending up at the Voiles de St Tropez, so in Switzerland construction is underway on a new test platform, L’Hydroptere.ch.

The Swiss connection with the team arrived in 2005 after L’Hydroptere had completed a crossing of the English Channel between Dover and Calais in a time faster than the 37 minutes pioneering French aviator Louis Bleriot had managed in 1909.

“In France they prefer bicycles or football,” says Thébault of his sponsorship situation. “After the Channel Crossing I wrote this book and Thierry [Lombard], a Swiss banker, read it and he called me. And he said ‘may I help you?’ I was happy because the boat was broken at time...”

With the support of Lombard and his company Lombard Odier, and later that of watchmaker Audemars Piguet, the goal has now been to take a new version of L’Hydroptere around the world. While Lombard and Thébault have set up their own engineering firm in Switzerland, on the new project they are also collaborating with the Eole Polytechnique Federale de Lausanne, who worked with Alinghi for their AC campaigns.

Interestingly while L’Hydroptere has a trimaran configuration, the new 35ft long test platform, due for launch this August, has more of a D35 catamaran configuration with a central flying hull and the main lifting foils in her floats. A advantages of the catamaran configuration are two fold – it keeps the lifting foils in the same fore and aft plane, which is good for the balance of the boat. The boat will also be designed – similar to the C-Fly we wrote about last week – so that the lifting foils can be retracted and she can sail in a conventional non-flying mode, to iprove her all round performance. Saying this Thébault reckons her take off speed will be 7 knots while her top speed is expected to be 45 knots. As this is a test platform for L’Hydroptere maxi, aimed at sailing offshore, the boat will also have a rig more suited to this, with reef points, etc.

L'hydroptere.ch

L'Hydroptere maxi

According to Thébault they won’t finalise whether the ultimate round the world boat, L’Hydroptere maxi, will have a tri or cat configurationsuntil they have tested L’Hydroptere.ch. However the simulations they have been running suggest the cat option is the superior. They have also to work out a size that is big enough to get them around the world but not so big that it becomes too unwieldy and beyond the limit of technology. One expects its LOA will be around 25-30m.

Into the creative melting pot for the new project has been brought both VPLP, who were central to the design of the BMW Oracle Racing AC33 trimaran, both Groupama 3 and the Banque Popualire maxi tris, as well as the Syz & Co foiler catamaran lake racer. Plus they have added yet another engineer into the mix in the form of Herve Devaux.

While they have been working on L’Hydroptere.ch for around a year now, Thébault doesn’t reckon they will start building the full scale offshore boat for at least a year. That will clearly be some boat – possibly the first boat to break the 1000 miles in a day barrier (or 41.6 knots average speed).

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