Above: Michel Desjoyeaux and his Farr Imoca 60 Foncia (above) won the 2008 Vendée Globe after restarting three days late; at the time his sail development programme – and the result – was looked at with awe by many of his rivals. However, two Vendée editions later and Foncia’s winning wardrobe looks pedestrian set alongside a 2016 Imoca rig like Armel Le Cléac’h’s Banque Populaire (right) with sails that wouldn’t disgrace a TP52… and yet in which Le Cléac’h has the confidence to set off around the world singlehanded
close the loop between our expertise supported by powerful numerical tools and the more intuitive sense of the sailors for what works.’
New cycle new sail
After all this comprehensive analysis, a significant gap was found where crews were pushing too hard on certain sails to fill voids in performance magnified by the decidedly small inventory. This resulted in risk-taking and breakages, which were not in anyone’s interest. So organisers along with North determined that the addition of one more sail to the inventory of the VOR 65s will be a cost-effective contribu- tion to performance and longevity. ‘We really looked hard at this, since cost saving is an important criterion in this race, especially since in the next cycle teams will only get two inventories starting in March 2017,’ said Sergent. ‘So when you evaluate this overall the addition of one new sail reduces the number of sail changes and the wear and tear on other sails.’ The details of the new inventory are still to be determined, but the teams who have to wrestle with their trade-offs in prepar- ing for this next race should be able to keep sail wear as a relatively minor vari- able. Sergent reckons that, based on the
52 SEAHORSE
last race, the new sails if well cared for should be within about 5% of peak poten- tial even after 50,000 miles and, in the case of a mainsail, as much as 3,500 hours’ use. For the 2017-18 event North will be using a durable version of the company’s Endurance filaments within the 3Di tapes, incorporating a higher proportion of Dyneema than in the last cycle. Sergent says that while Dyneema is an amazingly versatile material, they do have to guard against shrinkage, and so a small strain of 0.3% is assumed in the new sail designs. ‘A helpful feature of 3Di construction is that by layering tapes and building up the denier counts of carbon, Dyneema and Twaron aramid fibres [there is no carbon in the VOR sails but it is widely used for other classes] a third dimension is achieved in the structure of the fabric to handle loads in more than just the planar mem- brane surface,’ says Sergent. ‘An interior layer of tapes with a composite mix of fibre types and density can be engineered to handle loads precisely while also vastly improving durability.
‘This construction style has shown to be effective by having the outer tape layers handle the secondary loads, UV light and chafe, while the inner layers are designed to take on the primary loads,’ says Sergent.
‘This next generation of Volvo sails will have new structures with different ratios of fibres in the materials, based on what we learned from the last race.’ Another important change will be that the A3 gennaker will now be made of 3Di Force rather than Cuben Fiber. Testing done on the
100ft Comanche, maxis
Rambler and Wild Oats, Imoca 60s and MOD70 tris indicated that this new com- posite solution gives a better response time while flying in range and better shape retention at the upper edges of that range. So when the wind picks up this sail will not grow and distort, but keep its designed flying shape and then be easier to unload as the top of the sail’s range is reached. This is an important quality for any fast boat that relies upon flat sail designs.
Three years
This is the time Sergent says it has taken to develop the latest generation of sails for the Imoca 60s leaving soon on their jaunt around the planet. The offshore design world has always looked towards this class for innovation, and in this cycle the change has of course been revolutionary, the addi- tion of foils creating an entirely new level of performance, increasing boatspeeds by as much as 20 per cent in some conditions
YVAN ZEDDA
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