Farewell Archimedes
Sailing Hydraplaneur with Yves Parlier.
Hydraplaneur flying a hull Photo: TwinWhen a phone call from Ocea , Yves Parlier’s parent organization invited me to test this radical catamaran I found myself a week later in the company of a very special group of people – true pioneers of science, just as Archimedes more than 1800 years ago. With a displacement of only 5 Tons and the most revolutionary hull shapes in multihull history, Yves Parlier’s new 60’ offshore racer shatters Archimedes’ principles of hydrodynamics in formidable fashion.
The Team
Hydraplaneur’s (not to be confused with Hydroptere) complete name bares her sponsors and her believers: Mediatis, an international finance group and Region Aquitaine, the French region of the catamarans birth place. Yves Parlier’s achievements and heroic feats in the world of offshore racing have earned him world wide fame and a title of Chevalier of the Legion of Honor in France. His resourcefulness and belief empowered by an astonishing group of fluid mechanics engineers, designers and crewmembers have given birth to what is possibly the most advanced multihull in history. The Aquitaine Design Team acts as the nucleus and thinktank of the project: It consists of Romarick Neyhousser, Guillaume Verdier, Loic Goepfert and Gregoire Durousseau, who are the true brains behind Hydraplaneur. The hulls were visions of their minds and optimized by 1000’s of hours of computer modeling, fluid optimization calculations and tank tests. When I spoke to her builder Thierry Eleure he said what all honest builders think of their prototype boat: shaking his head: “…she is too heavy…” he grumbled.
On a more sober note, lets recall Archimedes’ principle: a floating object will displace a volume of water that has a weight equal to its own weight. From this theory evolved the law that the speed of a vessel cannot exceed more than 1.3 times the square root of its waterline length (Vmax=1.3x√Wl). Obviously this is only true for displacement hulls and Hydraplaneur, a beast of the air-water interface, is a machine, which defies this principle Big Time. In our sail in less than 19 knots of true wind the boat reached more than 28 knots. And we were not even pushing it.
Yves Parlier focusing at the helm
Innovations of the stepped hulls and twin rigs:
The key to Hydraplaneurs success is in not only in the shape of her stepped hulls but in her inherent ability to reduce loads where possible. In my mind this is her key to success. For instance the masts are not stepped on deck but on the strongest part of her massive crossbeams. Compression is further eased by a mast brace, which creates an articulating soft link up top and by shrouds, which are substituted by inner cross-stays. The mainsheet in combination with the roach of the main and the forestay keep the twin independently rotating wingmasts stable in the fore and aft direction and the spreader link acts as a stabilizer as her inner shrouds assure athwartship stability. It’s a very smart way to rig a boat, keeping the loads low and allowing for a much lighter support structure. The added benefit of the twin rig is that the center of effort of the combined sailplan allows for a higher righting moment versus a more conventional rig. Also in breezy conditions – usually encountered on a fast boat- reefing the leeward rig first also reduces some of the negative hydrodynamic pressure of the hulls, which further eases the loads.
Hydraplaneur photo: Twin
History. From seaplanes to Hydraplaneur:
In fact the principle of stepped hulls is nothing new, yet their application in offshore sailing yachts is a revolution. In the middle of the 80’s, Jean Francois Morice, an aeronautical engineer of Arcachon, decided to adapt the principle of stepped hulls of seaplane pontoons to high speed sailing yachts. He took out a patent and with Thierry Eleure constructed a 25’ catamaran with gliding hulls. In 1998, Yves Parlier and his team moved toward multihulls. His team was in search for different means of going faster than the existing F1 trimarans, by cheating the Archimedean principle. The stepped hulls were chosen for their simplicity and reliability in performance compared to foils. This is how the original Gerris research project, named after the aquatic spider, capable of swiftly moving across the water without creating any turbulence, was launched. A platform of a very powerful catamaran ( Beam/Length ratio of .82 !) was chosen over a trimaran. Indeed the cat is simpler and lighter than a tri of the same length, since one would only have to construct and support two hulls instead of three. On top of that, Hydraplaneur would be more powerful compared to a more conventional catamaran, thanks to her beam and the presence of movable water ballast. In 2002, tank tests were carried out. To do so three 8’ hulls were constructed: one Archimedean type and two stepped design hulls. These tests have enabled the Aquitaine Design Team to conclude the superior performance of the gliding hulls in calm waters and heavy swells.
Hydroplaning hulls have been successfully utilized in high speed powerboats as well as in seaplane designs. Originally the design of stepped hulls was invented to allow seaplanes to take off and land at high speeds. They enabled them to obtain a dynamic pressure on the water surface and hence facilitate squat of the hulls at certain speeds. Tests have also confirmed that a disrupted water surface ( a serious handicap for foilers) actually encourages these types of hulls to glide at high speed in a heavy sea. The gliding appears as an important token against nose dive. The stepped hulls also avoided the sudden braking effect of drag during landing. The speed of a stepped hull is virtually unlimited as some seaplanes take off at a speed of more than 180 mph and some offshore power catamarans can even go faster.
Most multihulls today – although they all initially are confined by Archimedes’ principle- eventually break free of it and attain high speeds by surfing. The difference with Hydraplaneur is that she is able to do it with less effort and much earlier.
Gregor Tarjan working the mast rotator on Hydraplaneur Photo: Gérard Fayol
Team Philipps, the slim hulled radical monster cat and Hydroptere (not to be confused with Hydraplaneur), an offshore foiler tri were other bold attempts to cheat Archimedes and take the high speed game to the open ocean. Both multihulls experienced mishaps as the loads imposed upon their structures were beyond the moduli or design parameters of the materials used. Team Philipps’ “keel” stepped masts imposed crippling loads on the partners and bearings just as the extreme length of the unsupported bows blew out and amputated an entire hull section. On the other hand Hydroptere’s complex foils experienced unacceptable loads at high speeds in the open ocean, which eventually stalled her progress. This is where Hydraplaneur, Yves stepped hulled cat will excel. Thanks to her hull design, the center of the dynamic lift is forward of the hydrostatic center of buoyancy and therefore enables her to effectively oppose the pitch- down momentum of the hydrodynamic force. As an example: at 40 knots the drag of the stepped hulls are 4 times lower than that of an Archimedean type hull and they magically remain stable at any speed. The design of her hulls and her twin rig are intelligent approaches to succumb an 1800 year old barrier. Only a massive construction failure could hinder Hydraplaneurs success.
Hydroptere, a radical foiler tri photo: Guillaume Plisson
How will she compare to the F1 60 tris ? Yves will do his best to leave them behind I can assure you. The aim of the Aquitaine design Team was to build a lighter and more reliable boat. This implied the need to design a cat, allowing the removal of the central hull. Despite the inferior width and inferior initial stability than the tris, to have a single mast stepped on the main cross beam would have been prohibitive in terms of weight. Indeed on a 45’ wide catamaran, such as Hydraplaneur, the compression of a single mast would become such, as it would need a huge beam to support. On the other hand, optimizing the sail area and lowering the Center of Effort of the sail plan, the use of a double rig was necessary. It is thus the configuration, of twin wingmasts (rotating but non canting), placed about 3 ‘ inboard on the main crossbeam, which was ultimately chosen. Interestingly the double rig exerts its main strain almost at the level of the hulls, so the only function the crossbeam has is to rigidly connect the hulls, allowing for a much lighter structure. Some people might think how ineffective this rig could be, as the windward sails might be sometimes blanketing the leeward rig. This is not so. On fast multihulls, such as Hydraplaneur- even in light or medium air, the apparent wind generated brings the wind far forward , even when running deep. This unique phenomenon avoids the leeward rig being shadowed by the windward rig. Lastly the smaller mast heights, compared to the F1 tris will make Hydraplaneurs rig more reliable.
Specifications of Hydraplaneur Mediatis Region Aquitaine:
Length: 60’
Beam: 49’3
Draft : 12’4
Displacement: 5 T
Vertical clearance: 78’7
Upwind sail area: 2582 sqft
Innovations and the Trickle Down Effect:
The history of sailing events is centered around speed records, technological leaps and all sorts of innovations. In 1986 Eric Tabarly showed us the way with his revolutionary trimaran, Pen Duick IV. 1978, Mike Birch won the first Route du Rhum on his 33’ tri Olympus Photo, just before Malinovski crossed the finish line on his 75’ monohull Kriter V. 1980 Eric Tabarly launched his advanced foiler-tri Paul Ricard. He beat the N. Atlantic speed record held by Charly Barr since 1912. But his idea was to “fly” with his multihull across the sea. A project under the name of Hydroptere, which was then later taken over by Alain Thebaud, a foiler tri of a new generation with a speed potential beyond that of present F1 trimarans, but whose design made it vulnerable.
The nature of ocean racing has enabled the French nautical industry to pull itself up to the number one world rank in innovations and the organization of competition events. Yves Parlier’s project is keeping with this line of research to find new solutions to keep on going faster in the open ocean. In 1985 the first mandrel spun- Kevlar shrouded carbon mast was introduced. 1993, first winch made of carbon fiber. 1996 First wing mast on a monohull. 1998 First transmission of video images shot onboard ocean racing boats. These important innovations, most of them pioneered by Yves, have been broadly spread to other racers and have found important applications in the marine business. It is no surprise then, that the most innovative production catamarans come from France.
The future plans for Hydraplaneur are well defined and center around showing any boat her twin transoms. At press time I was informed that Yves had successfully qualified for the STAR Singlehanded Transatlantic Race by sailing 1000 miles solo. This race will start May 31 from Plymouth GB and will take the lone sailor to Boston, where I will be waiting for him as shore crew. After his arrival in the US, the vessel will participate in the Quebec to St. Malo crewed transatlantic race. For the 2005-2006 season various ocean races and speed records are planned.
After my test sail with Yves I carried on North to visit La Rochelle, a beautiful harbor town situated on the Bay of Biscay. As I walked into a bar I could not believe my eyes. Here they were again: Yves and all of his crew, sitting tired and a bit shook up at a table. Their original plan was to do extended 10 day testing in strong conditions, so my surprise to run into them again after only 24 hours told me, something went seriously wrong. It was the PBO running backstay, Loic explained, which blew at the mast fitting. It was a non crucial event, since the rig does not depend on the runners to remain intact. Yves made the correct decision and headed back into the closest port, which was La Rochelle. The next day Loic, one of the principal designers and crew members called me and informed me of them hitting 36.8 knots in 25 knots of wind on their sail back to Arcachon. This speed was reached with a reef and leeward gennaker. Hydraplaneur too heavy ? I was grinning and so would Archimedes.
This article is published in Multihulls Magazine, July 2004. To see a short video clip of Hydraplaneur in action, please visit the Aeroyacht website: www.Aeroyacht.com Gregor Tarjan is founder of Aeroyacht Group, multihull specialists, a Long Island, NY based dealership, specializing in new and pre-owned multihulls.
Recently, Aeroyacht has jointly developed the Aeroyacht H42 performance cruising catamaran with Edel catamarans of France, a revolutionary multihull, which will be introduced in the next issue of this magazine.
“Catamarans Offshore”, Gregor Tarjan’s new book is scheduled to be published for the next season.
