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Foils on the IMOCAs – what the designers think

Les premiers bords d'Edmond de Rothschild
© Thierry Martinez / Gitana S.A.

A few weeks after the Fastnet Race and the day after a training race in Port-la-Forêt, what can we say about the performance of the foiling IMOCAs?

GUILLAUME VERDIER (ARCHITECT)© VINCENT CURUTCHET / DPPI / Vendée GlobeGuillaume Verdier: “As we saw in our calculations, foils are efficient when reaching. I have just spent 24 hours on Safran during the training course. In 15-20 knots of wind, we reached peak speeds of 28 knots! I was struck by the behaviour of the boat as she does very well. Thanks to the foiling appendages, she slams less and the shocks to the structure are better absorbed. That wasn’t something we necessarily expected when we designed the foils, so it’s a nice surprise. On the other hand, we saw in the Fastnet Race that the new 60-foot boats are handicapped upwind particularly in lighter conditions. Straight daggerboards are then more efficient. On top of that, the new class rules require a standardised mast and keel, which means the new IMOCAs have a bigger mass.”

Quentin Lucet, architecte au cabinet VPLPQuentin Lucet, designer at the VPLP team: “The races we have seen so far (SNSM Record, Artemis Challenge, Fastnet Race) gave an advantage to the best boats from the 2012-2013 Vendée Globe generation. But let’s not forget that these events took place on short courses and in general in 10-15 knots of wind. The new 60-foot boats were not designed for these conditions, which are not what you usually find in the Vendée Globe and even the Transat Jacques Vabre. It is therefore quite logical that the well tuned IMOCAs perform better than the boats which were recently launched. The teams and the designers need to keep a cool head.”

“Finding the ideal compromise to improve the all-round characteristics of the boats.”

So we’re still in the learning phase?

G.V.: “Yes. People would like to have seen the new boats sail faster from the beginning, but it is never as easy as that. As the number of appendages is limited to five, we have to find the right set up to allow the boat to be lifted up  when sailing downwind and to avoid drift when going upwind, which is not that simple. We think we have made the right choice with the Vendée Globe in mind and we are now checking that out on the water. We still have enough time and it would be a pity not to go down this track. This learning phase is fascinating, but it does raise some questions and doubts. It’s never black or white on these matters.”

Q.L.: “The rules do not allow you to modify the incidence of the foil. So we have to find the ideal compromise to improve performance when reaching and not to lose too much when sailing upwind. This involves minor changes to the set up and adjustment, which should, we hope, improve the efficiency of the foils, making the boats perform better in all points of sail. We’re still trying to understand everything about these foils. We have seen some very promising results and we need to continue to sail now to work on how to get the most out of them.”

Morgan Lagravière sur le foil de Safran© Jean-Marie Liot / DPPI / SafranEven so, the foiling boats, even if well adjusted, will never be as good all round as those with straight daggerboards, like PRB and SMA…

Q.L.: “It’s true that the new boats are designed for more specific conditions and perform better in certain points of sail. Fitting foils has meant taking risks, but the risk is limited, as we carried out a huge number of studies and routing using the Vendée Globe course. But we might encounter a year when the conditions are particularly strong or light…”

Are the foils identical on all the boats?

G.V.: “They look similar, but there are nevertheless some minor differences. Each skipper gave us a list of specifications concerning the use of the foils and we respected their individual choices.”

Q.L.: “It’s true that at first glance, the foils look the same. In fact, the difference chiefly concerns the shaft (the part that comes back into the housing, editor’s note) while the tip (the winglet that is perpendicular to the shaft) is practically the same from one boat to another.”

“Some tricky choices to make after the Transat Jacques Vabre and the BtoB”

Can we imagine a return to straight daggerboards after the Transat Jacques Vabre and the Transat BtoB?

G.V.: “Yes, we’re only looking at two daggerboards. The boats were designed with the possibility of moving back to them. Anything is possible.”

Q.L.: “In terms of the geometry, it can be done, but it’s too soon to start thinking like that.”

You have an exclusivity clause, which prevents you from working on foils for the boats from the previous generations, which is valid until 1st January 2016. Have you already been asked by any teams to replace the straight daggerboards with foils?

G.V: “All of the big teams are interested, but for the moment, they’re just watching what is happening before changing everything. For them too, there will be a difficult choice to make at the end of the year...”

Interview with Olivier Bourbon / Mer & Media Agency

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