Fly Higher. Travel Faster. Last Longer. - Part Two
by John Curnow, Sail-World.com AUS Editor 25 Aug 09:00 BST
Gitana 18, the new Maxi Edmond de Rothschild © O.Michon / GITANA S.A.
In Part One of wFly Higher. Travel Faster. Last Longer. we got to see just how Gitana 18 is different, and most importantly, why. So then, let’s get straight back into it… Let the sub-headings take it away.
Alphabet soup
When it comes to appendages, we've had so many letters of the alphabet already; C, T, L, J etc. The U rudders have always intrigued me. The answer lies in the higher flight of Gitana 18, meaning the rudders too are a half to one metre longer, and yes they are careful about specific numbers, for a reason. More stability would be required, so as to provide better flight more often, and in more waves, with utterly immense loads to be controlled.
"Structurally, there were tradeoffs with the classic T. The idea of the U came from Guillaume (Verdier) at the beginning. There are two reasons, with the first being that obviously the elevator stays horizontal when the rudder takes on load, which aids in stability via more sustained lift (Gitana 18 flies 500-750mm higher), and the second one is that you have a much better control spherically of the boat, because your rudder doesn't deform as much on the load. So when you accelerate or jump a wave, your rudders aren't moving under you. In some of the AC videos, as soon as something like that happens, you see that the boats lose control. Finally, the autopilot should also have a better time in controlling it all," stated Sainson.
Personally, I never tire of listening to sailors tell me how they live on board given those kind of speeds, the shocks and the forces. It could be a bit like turbulence on a commercial airliner where your beer can goes from your table to the roof in under a second. Caudrelier says, "I think life on an Ultim is better than on an IMOCA boat because the boat is huge (32m LOA with a 23m beam!!!), and foiling gives you more stability, so there's less movement, and it also reduces the impact of the wave on the hull."
"Compared to a monohull like an IMOCA, when it falls down in a wave, it has its big bow to stop it. We have very narrow hull, so it doesn't stop the boat, except if you have a huge nose dive, which has never happened to me, or if you hit something very big, so you never have some big reduction of the speed. So I think life is not so bad on board, and it is way better than an ORMA 60 or MOD70. I prefer to be on an Ultim, and also you sail with no heel, so you feel very safe."
"Also, you are far away from capsizing. It can happen, if you have to material failure, but the size and the foils give you really safe control of the boats. We work a lot on managing the loads, especially when you do manoeuvres and move some appendages, so the systems use the speed of the boat to the lift of the appendages. We found with Gitana 17 that we could do manoeuvres in perhaps two minutes. I think this is one of the reasons why we were performing so well, especially single-handedly. We have fantastic systems, working perfectly together, and I could tack in five minutes, and then get on with tuning the foils, whereas some boats put 20-25 minutes to do foil up and foil down on the other side."
"We also work a lot on ergonomics of the cockpit. We have improved on the fantastic cockpit of Gitana 17, and worked with the VR to help design the simplest cockpit for a single handed. Even when crewed it is still better, by virtue of simplicity, and it is all about a better life on board. Better sleeping, cooking, eating and so forth, which ultimately leads to better human performance to make the boat go perform better."
Clearly, if you have less load on the human(s), they're going to be less tired, make better decisions, and so forth, and this is being played across all the systems of the boat to look after the human, thereby continually achieving the highest possible speeds.
Caudrelier adds, "Exactly, if you spend 25 minutes to tack, which means 20 minutes to grind your foils, you are exhausted, so at the end when you are finished to grind the foils, you have less power to trim the sails. I remember I tacked probably 10 or 15 times during a day, because of the ice limit, and I don't think the other one were able to do it at this moment, so that also gives you a possibility to make a better tactical play, because you are not afraid to tack. Sometimes the question of the guy who is doing the routing, and they ask, 'Are you able to tack two times, or are you exhausted?' I say okay, because I know it's easy and I can do it."
"Many times I've seen the opponents not to do as many tacks or gybes as me, because I think it's too tough on board their boat. It's part of our background, our experience, and it took us a lot of time to develop this system, and I have to admit that on Gitana 18, everybody said, 'Oh you have so many systems, you are going to be exhausted', but I think we've done a fantastic job. Yes, it's a bit more complicated than the other boat, but because we knew about that, and we thought about it, we managed to produce some very efficient systems."
Smarter in every way
Sainson added, "It was top of mind when we did the U-rudders, the big foils that have to be hidden behind the fore beam, the canting centreboard, and everything else. The proportion was, 'It has to be easy to manoeuvre and fast', so as Charles said, that could be with releasing things by the water help you, or reduce friction, and even when we designed the appendage shape sometimes."
Sainson also points out that, "If you lose 20 minutes in your tack or gybe, and you do five or six in the day, as theses boats do 35 knots, sometimes you lose more on five gybes than you would lose with one percent performance on the foil. In the last Route du Rhum, Charles got 40-50 miles ahead of the other boats very quickly just because he manoeuvred better, and quicker."
Clearly, the experience is unlike any other that most sailors will ever get to comprehend, even with a good go at the simulator. So what is like to foil, not really dropping off, and it is predominantly stable, with the bulk of the turbulence going on underneath you. Do you really don't notice that you are actually flying that high?
Caudrelier said, "No, you don't really feel it. We have not sailed that much in big sea state for the moment, but we've had the feeling, compared to Gitana 17 and flying higher where we met two or three metre seas, that there was no sea state! In the discussion on board, I was saying that I didn't think the sea state is so big, even though we were watching the model showing, 2-3m, and we were surprised that the boat was flying so well in these conditions. It was like three was no wave."
"We knew with Gitana 17 when we got past 2m. Now we think the same point is 3m or a bit more," added Caudrelier to demonstrate the differences. "We are waiting for the moment to fight against our opponents, but for now we are not ready. We need to work on our side, improve the boat, and find how it works, because we don't have the perfect playbook, and it's really different in behaviour compared to Gitana 17, especially as we have a less leeway, and it has really changed the behaviour of the boat. So, we have to adapt the way we trim the sails, and the way we drive the boat, and understand her reactions, which are very different."
"I have not managed to push the boat, as I was with Gitana 17, because I knew it perfectly. She never had a bad reaction, or put me in danger, but the new boat is more nervous, and everything is also stiffer, so you feel it on board. Sometimes you have the feeling that you are pushing the limit too much. Every single day we sail, we discover that we can push more and more, but for now I'm not sailing at the same level as I was sailing on Gitana 17, but every day I improve."
Talking with one person, who has set a record on an ORMA 60, and the comment was that they felt safer at 39 knots, than they did at 31 knots. We'll call that harmonic resonance; the natural order. So, Gitana 18 is stiffer, is it therefore harsher?
By way of explaining, Caudrelier says, "When you have speed, you are never in danger, except if you go too fast. The first problem is cavitation, especially on the rudder, then on the foils. It's not so bad, because you fall down, but you have the hulls and the boat is stable. However, when you have cavitation on the rudder, you've lost control, which means you don't know which direction the boat's going to go. If you are sailing downwind with a big gennaker and the boat comes up, then you are in danger, and equally, if you are sailing upwind and the boat bears away very quickly, you are in danger."
"We certainly felt it more in Gitana 17 at very high speed. Now we are safer between 35 and 40 knots, because we have more control of the boat. The problem is when the speed drops, then your upwind angle increases a lot, and the boat wants to accelerate, or the autopilot tries to accelerate. Then you have this transition between non-flying or bad flying, and then you fly, which is really dangerous. This is where you feel it."
Parameters
"So, when you have steady high speed you are comfortable. I remember when driving Gitana 17 above 42/43 knots that you felt the sensation that the limits were really close and you were scared to lose control. The new rudder system means no more problems. I was surprised one day that I was driving Gitana 18, and I was not watching the number because the screen was off, and I had the feeling I was at 35 knots, and then I saw the speed, which was at 42, and I was feeling no fear. The control was perfect because of the U rudder."
"It really has changed the game. It's like a car that has poor suspension and bad tyres. You slip and you are in danger, you can lose control. I think we will be able to really push Gitana 18. We have not yet done 45 or 46 knots in a very big sea state, but my first sensation is that we are safe until at least 35 knots, because we have a perfect control of the boat with this rudder."
"We will gain 10 or maybe 15% in these conditions over Gitana 17."
Sainson added, "In the Southern Ocean where the boats would accelerate a lot in waves, we would set the limit at 43/45, for otherwise it would go off easily to 47/8/9 knots. So we set a 10-knot band of 33-43. Gitana 18 should be more like 37-47, and clearly make 50 under acceleration. If Charles feels safe, then maybe just let it go. Often when going around the world, Charles was saying I'm more trying to slow down the boat, than make it accelerate. Now, as much as possible, we might be able to leave it to go the speed it wants to."
A lower drag window such as having the foil tucked up behind the beam will assist, because of aerodynamics, and it won't get hit by as much of the wave action, which adds to durability, as well, and that is clearly part of the overall design ethos.
Saison added, "The foil is very important on two fronts. When you watch videos of all the big trimarans sailing, the windward foil is always hitting a lot into the water in the big waves. Firstly, it takes off a few knots, and then you have to re-accelerate., so that was the first thing. Next, we realised more and more that we were damaging the foils a lot, especially the foil that was not used. There's the bearing, but also the paint and even the carbon finish by getting damaged. On the round-the-world, we discovered that between the beginning and the end, even if you haven't broken anything, the loss in performance is really significant."
"By the end of Charles' last RTW, he still managed to fly, but it was more difficult to fly because the foil was not the shape anymore," said Sainson. Then Caudrelier also recalled, "The last day when I did the delivery after the end of the Arkea Ultim Challenge, we had perfect conditions for flying. We were struggling to reach 80% of the polar, and most of the issues were coming from the appendages. I was between 70-75% of my normal performance in this condition. So, a big loss."
So clearly a foil that is essentially out of the water, presenting a scant profile, and predominantly protected by the beam will be super advantageous from both an aero POV, and over time from a degradation POV. Equally, locking in some of your 10-15% gains over the older boat just makes sense. Again, part of the design ethos is to keep the maximum performance of the systems for the longest possible period of the RTW trip.
Part Two is now complete. Never fear, there is more to come. Loads more as it turns out... Stay tuned for the finale with Part Three!
Want more in the meantime, well here is the link to the Gitana Team channel, and below is a list of the great content you can find there -
Flying Offshore Web Series
This series captures the high-stakes journey of the Maxi Edmond de Rothschild as the team prepares to defend their Route du Rhum title.
Episode 1: In the Beginning - The transition from carbon reality to the liquid element as the boat hits the water.
Episode 2: Step by Step - The technical "first steps" involving rigorous stress-testing of the latest foils and rig.
Episode 3: Ehe Sailor and the Machine - A deep dive into the physical and mental preparation required for Charles Caudrelier to master the high-tech 32-meter giant
Episode 4: First foil, first flights | Flying Offshore - A behind the scenes look as the team head out offshore to try foiling for the first time on the first foil
DNA Web Series
This series delves into the entire creation process of the Gitana 18, from the initial concept and design to the final manufacturing.
Episode 1: Conception - Focuses on the initial design and the hydro/aerodynamic risks taken during the project.
Episode 2: Construction - Details the physical building phase of the vessel.
Episode 3: Artistic Identity - Explores the visual and aesthetic design and the "kinetic" livery.
Episode 4: Du Virtuel au Réel - Features the transition from digital models to the physical boat.
Episode 5: Expertise Internationale - Highlights the innovation hub in Lorient and specialized testing tools.
Episode 6: Teamwork - Showcases collaboration between the hydraulics, electronics, and design departments.
Episode 7: Reveal - The official unveiling of the finished Maxi Edmond de Rothschild.
John Curnow
Sail-World.com AUS Editor