{"id":2919,"date":"2016-11-14T09:30:12","date_gmt":"2016-11-14T08:30:12","guid":{"rendered":"http:\/\/www.guillaumeverdier.com\/en\/?p=2919"},"modified":"2017-01-20T10:40:05","modified_gmt":"2017-01-20T09:40:05","slug":"imocas-from-the-old-to-the-new-generation-of-boats-by-guillaume-verdier","status":"publish","type":"post","link":"https:\/\/www.guillaumeverdier.com\/en\/imocas-from-the-old-to-the-new-generation-of-boats-by-guillaume-verdier\/","title":{"rendered":"Imocas, from the old to the new generation of boats. By Guillaume Verdier."},"content":{"rendered":"

Aiming for light, powerful boats.<\/strong><\/h2>\n

The evolution of Verdier\/VPLP IMOCA over three generations<\/em><\/strong><\/p>\n

2007-2008: First generation<\/strong><\/p>\n

In 2007, I was part of the K Challenge design team for the America\u2019s Cup in Valencia. In collaboration with Bernard Nivetl, I designed hulls that were very wide at the bow and stern, with very steep sides. In parallel, we studied the compromises between the hull\u2019s stiffness, the wetted surface and wave lengths. Powerful bows turned out to be efficient because they extend the wave created by the boat.<\/p>\n

<\/p>\n

This was also when I started collaborating with the VPLP design office. We worked together on the design of Marc Guillemot\u2019s Safran <\/strong>(currently Yann Elies\u2019 Queguiner) and Kito de Pavant\u2019s Groupe Bel<\/strong> (now Thomas Ruyant\u2019s Souffle du Nord).<\/p>\n

The designs we came up with broke away from previous IMOCA boats and had the following particularities:<\/p>\n

The chine is distinctive and spreads over the entire length of the hull, 5.50 m wide. There is less wetted surface than before. A first for 60 foot boats. The hull sides are also very vertical. Then, the bow volume is very pronounced, with straight water lines when heeling and no longer inversed like they used to be.<\/p>\n

The keel is very far back and we put tilt on its axle, meaning we inclined the front of the axis towards the top, allowing the keel to work along the same line as the heeling hull.<\/p>\n

Concerning the deck plan, we decided to centre weights and lower the centre of gravity. The mast is a classic one, with three spreaders (Groupe Bel chose a wing mast). It is also removed aft, favouring reaching and facilitating sail manoeuvres (reefing). Thus, the mainsail is very slender. Its structure is also rather original since it is very ramified (like leaves on a tree), enabling great resilience in the event of damage.<\/p>\n

To test these innovations, we used increasingly sophisticated digital tools (Computational Fluid Dynamics software) helping us better apprehend compromises. We also tank tested them to predict performance. These boats turned out to be very powerful, although modestly sized. They behave well in the swell since they don\u2019t nose dive into it.<\/p>\n

2009-2010: Second generation<\/strong><\/p>\n

Between 2009 and 2011, VPLP and I designed four new 60 foot boats together: Vincent Riou\u2019s PRB<\/strong>, Jean-Pierre Dick\u2019s Virbac-Paprec 3<\/strong> (currently Kito de Pavant\u2019s Bastide-Otio), Armel Le Cl\u00e9ach\u2019s Banque Populaire<\/strong> (now J\u00e9r\u00e9mie Bayou\u2019s Maitre Coq) and Fran\u00e7ois Gabart\u2019s Macif<\/strong> (now Paul Meilhat\u2019s SMA).<\/p>\n

Our reference was the initial concept of Safran, which turned out to be very efficient. We wanted to push boundaries, drawing from sailors\u2019 feedback. Making theory and practise come together.<\/p>\n

For PRB, Vincent Riou wanted to simplify the boat. Every carbon ply was put into question, in order to always lighten the boat. In the end, after a mechanical slimming diet, we reached an unimaginable weight result. The hull is the same as Safran\u2019s. The chine hull is also 5.50 m. The deck changed because Vincent Riou considered that it had to be adapted to his sailing methods. As for the wing mast, it has outriggers which spread out the staysails\u2019 clews.<\/p>\n

For Virbac-Paprec 3, we developed second generation hulls. The volume at the front was increased, to compensate the sails\u2019 power. Once again, we relied on sophisticated scientific tools. We tank tested it in the Woolfson unit (in Southampton), which enabled us to ensure the boat\u2019s marine quality. We also did swell testing. We also used CFD software to understand where the resistance in various parts of the hull comes from. Thanks to these tools, we managed to design a boat with a stiff hull, that doesn\u2019t plough when reaching. This was a major step forward, considerably optimising new generation 60 foot boats. The chine hull is 5.70 m. We opted for a very light and compact classic mast, developed by Southern Spars.<\/p>\n

Banque Populaire and Macif are sisterships. In their design, the following elements are noteworthy: a powerful bilge hull, 5.70 m beam, a wing mast, a straight daggerboard, carbon keel for Banque Populaire and a steel one for Macif, and a deck the shape of a seagull\u2019s wing. This was Michel Desjoyeaux\u2019 idea, who saw a structural advantage, for dunnage and storage of sails in the centre. It was at his request that we created a complex network of tunnels under the deck.<\/p>\n

Macif and skipper Fran\u00e7ois Gabart won the Vend\u00e9e-Globe 2012-2013.<\/p>\n

2015-2016: new generation<\/strong><\/p>\n

For the 2016-2017 edition of the Vend\u00e9e Globe, the class standards changed. The wing mast and one piece keel are imposed. VPLP and myself got in contact to create six new boats: Morgan Lagravi\u00e8re\u2019s Safran II<\/strong>, Armel Le Cl\u00e9ach\u2019s Banque Populaire<\/strong>, S\u00e9bastien Josse\u2019s Gitana<\/strong>, Jean-Pierre Dick\u2019s St Michel-Virbac<\/strong>, Alex Thomson\u2019s Hugo Boss<\/strong> and the last to be launched was Pieter Heerema\u2019s No Way Back. <\/strong>We looked for a way to optimise performance. This was where the foils came in.<\/p>\n

First, we tried our former concepts with a similar scientific package to previous designs. Then, stemming from our experience on the design of Team New Zealand\u2019s AC72 for the America\u2019s Cup (2013), we decided to introduce foils into the design of the new 60 foot boats.<\/p>\n

These innovative foils are made up of three sections: the shaft, the elbow turn and the tip. The elbow creates the vertical lift force and the tip provides the side force. We call them Dali foils because they look like the famous painter\u2019s moustache.<\/p>\n

During the conception of these foils, we collaborated with Len Imas who I worked with at ETNZ, and Romain Garo, for the flow calculations (digital simulation of the boat\u2019s drag). To reach a compromise, we used the VPP (Velocity Prediction Programme) conceived by Dan Bernasconi. VPLP launched and supervised wind tunnel studies, in parallel. Also, I developed digital platform of finite element calculations with Benjamin Muyl, to assess the boat\u2019s solidity.<\/p>\n

We aimed to make the boat more homogenous, while predicting increased violence of the wave impact. Rigs and keels were brought back. The front shapes are fuller to compensate the increased thrust of the sails.<\/p>\n

The foils relieve almost all the boat. We improved their performance in the second set making them thinner and less disruptive at the water surface. The tip plays a huge part in this.<\/p>\n

Gitana and St-Michel-Virbac associated for their boats\u2019 design. The deck plans are different than previous versions. The deck gear is lowered and the cockpit is entirely covered. The new hull we provided is very long, despite the fact that it is not always relieved by the foils (when sailing upwind for example). The new IMOCA class standards restricted the ballast volume, but the quantity of water on board is lowered.<\/p>\n

Hugo Boss was developed for a radical programme, following Alex Thomson\u2019s decisions. The foil pushes a greater part of the boat\u2019s weight. The boat is a little narrower. You must work assiduously to benefit from the dynamic balance. The sailor must be very careful to always tune the boat in the best way (sails, keel angle, daggerboard).<\/p>\n

Conclusion on the finish line.<\/p>\n

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They collaborated on IMOCA projects:<\/em><\/p>\n

Guillaume Verdier\u2019s co-workers:<\/u><\/em><\/p>\n