Stronger and smarter
The Imoca class can be said to be in a period of transition. Rudder elevators are (still) prohibited so designers and teams have been putting maximum thought into achieving steady flight without a key control device normally deemed essential. Compromises explored in turn generate increased demands on the engineers to allow seemingly unnatural solutions to perform well. Jocelyn Blériot discussed some of these left-field challenges with the engineering team at Gurit including structural engineer Paolo Manganelli
As we were watching a small number of Imocas battling it out around the globe fully crewed for the first time, a new gener- ation of 60s was being launched and put through its paces. To try to understand the latest thinking in structural design, and to evaluate how far the most recent boats had evolved from the previous generation, we spoke to Gurit’s Paolo Manganelli, Yoan Stephant and Nicolas Poidevin. The firm has been involved in three of the most recent projects, in each case with a different set-up: directly contracted by Jérémie Beyou’s Charal team, in collaboration with VPLP for Malizia, and coming in to double- check the work for Eric Bellion and Jean Le Cam’s efforts. Three configurations, three different philosophies… and a host of new parameters to play with. For Malizia the focus was firmly on relia- bility, with a ‘clear demand from the team’
54 SEAHORSE
on that aspect, stresses Paolo. Compared with the previous generation of boats this meant significantly pushing the require- ments in terms of structural strength. The Gurit team readily admits that they
went into the discussion trying to take a bit of that edge off, which led to some in-depth discussions before landing on compromises that today feel like the right balance. ‘Malizia wanted to put the emphasis on the boat’s ability to deal with rough seas, which had an influence on hull shapes, notably in terms of freeboard height,’ says Manganelli. The idea was also to be able to launch without running the risk of having to return to the yard soon afterwards – and if that meant a bit more weight from the outset, well, so be it. Reliability was also, naturally, an objec-
tive for Charal but the team in this case did not set precise minimum requirements. ‘Sam Manuard, Dimitri Nicolopoulos and ourselves were around the table,’ says Poidevin, ‘and we agreed on thresholds based on the experience acquired on L’Occitane and Charal 1.’ The group knew that hull bottom
strength would need to receive special attention, and this guided structural con- siderations, but the brief was not as pre- scriptive as with Malizia. It comes as no surprise that all teams
want a boat that can endure what a Vendée or Ocean Race can throw at it, but the ways in which that criterion expresses itself are contingent on the skipper’s experience(s). ‘Part of the input comes from structural engineers, based on past projects’ learnings and data, but the client has the final say,’
notes Paolo Manganelli. ‘We have limits beneath which we do
not want to go, but where the cursor is placed above this minimum is down to the racing team. We saw that with Malizia, who were keen to go well above our limit – in a sort of belt and braces approach. Others can be more… shall we say playful? ‘And of course when thinking about
reliability trade-offs, the worry is always about being heavier than the competition.’
Load inflation all around Interestingly, Poidevin stresses that ‘experi- ence does not necessarily make discussions more straightforward’, as perhaps the temp- tation to experiment is greater, and with it comes a new flurry of questions. Younger teams tend to stick to their guns
and know precisely what they want to avoid – in other words, not being able to finish due to gear failure. Structure is a key weight factor, and weight has an impact on perfor- mance, ‘but, having said that, accepting a sacrifice on structure weight can also allow you to take risks elsewhere, it’s definitely not a binary choice’, Manganelli muses. Whether the weight impact is greater on
foiling boats than on their predecessors is an interesting question: it’s clear in transi- tion and pre-flight phases, but because the loads are also greater in foiling mode teams that have heavier (hence stronger) boats may be less hesitant to put their machine under stress when things get rougher. Poidevin weighs in: ‘This probably plays
out more on a RTW race than on a Rhum- type transat, and to look at the big picture what we’re talking about is a 150-200kg
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