The design secrets of Charlie Dalin’s Vendée Globe leading IMOCA revealed

Charlie Dalin’s latest generation Macif Sante Prevoyance is one of the most innovative new launches in the IMOCA class and among the favourites for the current Vendée Globe

Charlie Dalin approached the 2024 Vendée Globe with a unique perspective. Dalin’s previous boat, Apivia (now Clarisse Cremer’s L’Occitane en Provence) was one of the benchmark IMOCAs of its generation. So fast, in fact, that it wasn’t until Dalin arrived in Les Sables d’Olonne in January 2021 that it became obvious just how hobbled Apivia had been, with a MacGuyver-esque arrangement of improvised stays supporting the port foil for 13,000 miles.

Dalin was first across the line in the 2020/21 race, though eventually finished 2nd after Yannick Bestaven received redress time for his part in the rescue of Kevin Escoffier.

So when it came to creating a boat for the 2024 race, his target was to try and improve on a design so quick that it had effectively dominated the Vendée Globe fleet while sailing at reduced performance.

“Apivia was a really good boat,” Dalin explained. “In almost any condition, it’s just an amazing boat. It’s easy to go fast and it’s easy to maintain a high speed. But the boat had a small weakness: running dead downwind with a big sea state. That was a bit complicated.”

Fellow Vendée Globe skipper Yoann Richomme went further. “The conclusion of the 2020 generation was that they were bloody fast, and the foils were improving all the time, but the hulls were awful in the way the bows were digging all the time,” he told us in Les Sables d’Olonne.

For the 2024 IMOCA cycle the design evolution has mostly centred on two major areas of improvement: hull shape and ‘liveability’. The aim is to create a hull shape that can handle big seaways without the huge speed losses – and damage potential – of slamming and nosediving into waves, but maintain fast, smooth averages.

Meanwhile there has been an increased focus on the interior spaces and how the skippers can safely survive – let alone perform at their optimum – at the sustained high speeds and brutal motion of a foiling IMOCA. Across the fleet there has been an intriguing variation in how to solve these problems.

Moving the volume

To draw his new Macif, Dalin returned to work once again with legendary IMOCA designer Guillaume Verdier. Verdier’s wizardry is evident from first glance with Macif’s complex hull form. There is a lot going on here.

The overall shape is the first thing that’s most striking; long gone are the days when IMOCA transoms flared out to maximum beam. “Because of how we managed to harness the power of the foils, we realised that there was a possibility to make a narrower hull shape, especially on the transom. And because we really wanted to get rid of this nose-dive problem, we essentially moved the volume forward,” Dalin explains.

“So we got narrower at the stern and made the boat as wide as we could, according to the rules, further forward, to give it as much power as we could in the forward sections, to avoid the boat going down [the mine].

“We’ve also got a bit more rocker, so the boat can sit a bit higher naturally. It’s a more natural position for the boat to sit when you’re sailing downwind, but reaching is not so good. [Combined] with the width distribution, we got a smaller wetted surface area compared to Apivia, so it’s better all round. The first time we went sailing on the boat, I really felt like the boat was less draggy in the water.

“If you look at the bow, it’s vertical at the sprit, at the very tip. Then we’ve got a hard chine all the way forward.”

Richomme also observed that the lower chine helps Macif take off at lower angles of heel, and lower speeds, for earlier flight.

A ‘drier’ ride

As well as a hard chine, there is a relatively deep ‘strake’, which helps wave deflection – keeping water off the bow and off the deck is key. Again, designers of the newest boats have tried to tackle this problem in different ways.

On Macif the deck has a slightly ‘gull-wing’ organic shape, rising to mounds on either side, with its higher freeboard also helping keep the bow out of the sea. Dalin says there are multiple gains to it: “Having a deck which is this shape gives it a natural rigidity. The water presses against it, and if it was flat, that would just break.

“It’s like the inside of a cardboard box; you find this little wavy pattern. This makes it more rigid naturally, so you can put in less carbon.

“The second reason is because you’re lower down in the middle of the boat, you’ve got smaller bulkheads as well. And also, you lower your centre of gravity on the deck.”

Structurally, getting the sides of the deck to take some of the loads and bending forces is advantageous, as he explains: “Basically, you’ve got 20, 25 tonnes pushing on the mast step. Then you’ve got the runners at the back and the stays forward. So the boat wants to bend. Having the sides of the boat higher means that some of the efforts are running on the side part of the deck.”

And because every part of the boat has been thought through in enormous detail, what looks like a simple toe rail is also structural trickery.

“We’ve added this little flange on the bow. With this feature, the water is just evacuated to the side. And it helps the structure for sure – instead of having something that’s useless inside the boat, like a horizontal stringer, this is multi-purposed.”

Cockpit evolution

The area where Macif most departs from the rest of the fleet is inside. Covered cockpits have become a huge trend, with everything from Ultims to Class 40s pulling protection further and further aft to keep skippers safer and drier. Alex Thomson’s Hugo Boss was probably the most radical IMOCA of the last generation for this, with a completely enclosed cockpit. Thomson’s ‘living’ space was something of an afterthought though – with a combination of bean bag and chair wedged in.

Skippers have gone for different arrangements this time around, with a raft of solutions to create a protected navigation and sleeping area. Sam Goodchild and Sam Davies both have aft-facing reclining and canting chairs in a central companionway, so they can view their screens while hurtling along, and won’t get thrown forwards. Alan Roura, whose Hublot is the former Hugo Boss, has a reclined ‘double’ chair behind the cockpit aft bulkhead so he can sit or lie on either tack. Richomme’s cockpit is entirely covered, and has a forward-facing chair with mountain bike suspension (Davies’ seat also has suspension based on that used on RIBs).

Dalin has gone for a unique solution: a covered cockpit forward, with an even more protected living ‘pod’, which he calls the studette (or studio) aft. The whole premise is based on reducing movement – both for efficient ergonomics, and the more dangerous involuntary movement of being thrown around as the boat nosedives or falls off a wave.

The less energy Dalin spends on clinging on, or staying warm and dry, the more energy and focus he can spend on eking out every fraction of performance.

The spaces are intentionally small – just 5m2 – and the number of steps between each ‘function’ has been carefully thought out. It’s just 1.5m from his bunk to the chart table, and 1.5m from chart table to winch column.
To create the spaces, a 1:1 scale model of the cockpit, including articulated coffee grinders, and living pod was set up in Dalin’s team base at MerConcept, Concarneau, while the boat was built at CDK, Port la Forêt.

In the cockpit, he opted for four winches rather than five for reduced weight, but the team worked hard on finessing the ergonomics. “On Apivia, we had the four winches in a line. At the beginning we thought that was a good set up. We tried, but it was not really working well with the tunnels on Macif. This set-up is actually better.

“The jib sheets, J0, fractional, the runners… everything goes through these tunnels. And for all these sheets, we can use three out of the four winches.”

Charlie says that on the last Vendée even a simple act like filling up his jet-boil to make food involved frustrating, energy-sapping scrambles around the cockpit. This time everything has been packed into a compact space with everything Dalin needs in arm’s reach from his mission control chair, like the pilot’s seat in an aircraft cockpit. The main screen is repeated in both the cockpit and nav station also.

Ventilated

Keeping the water out is of essential importance, but Dalin emphasises that ventilation was also given a lot of focus. He has two access hatches on either side of the cockpit which have a three-way closure that can keep out water sweeping down the deck, spray from above, or be fully closed/open. There are also aft facing portholes that can be opened for ventilation, and air circulation has been built into the studette. Forward facing perspex ‘look outs’ offer visibility.

Both his bunk and chair went through several iterations. The bunk is lengthways in the compact space, with Dalin’s feet up against the forward bulkhead, and a deep custom-shaped mattress that might just be the most comfortable racing yacht bunk ever.

His chair was created after a 3D body mapping process and built to his exact shape. A window aft lets Dalin keep an eye on conditions outside as well as the mainsheet track. It also means his is, he believes, the only IMOCA to offer a bed with a sea view!

Enjoying the process

For Dalin, who is a trained naval architect, the process of designing and building Macif has been fascinating and he was closely involved in all areas. “It’s such an amazing, interesting part [of the campaign] because you take decisions every day that are programme-changing decisions. Once you hit the button of your hull shape, that’s it. You’re committed for four years.

“I had something to say on everything. The hull shape, foil case positioning… things that are not impossible to change, but are pretty fundamental, and extremely expensive and time consuming to move. I think we moved the foil cases just at the last minute!

“I always loved to think and rethink about it during the night. Then in the morning, I’d come up into the design office and say ‘I had an idea last night. Maybe it’s bad, but listen up, guys!’ Sometimes we keep it, sometimes we bin it.

“But it’s such a fun project, such a fun process. You are making a boat just as you want. As a naval architect, it’s something I really enjoyed, both for Apivia and Macif. It was really cool.”

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