FOIL FOCUSED

March 6, 2013 - Behind the scenes at Oracle Team USA, Joseph Ozanne crunches numbers using mind-numbing equations all in the name of a faster time around the racecourse for his team’s AC72. Ozanne is the team’s wing design leader and is also responsible for the performance prediction functions. Much of his work in the current campaign involves the daggerboards, which he believes will be critical to a team’s success in the 34th America’s Cup. Now on his third campaign with Oracle, the 34-year old Frenchman has had plenty of experience working with the best in the game.

What’s been the biggest change for you over the last three campaigns that you’ve worked with Oracle?

JO: As a designer, the biggest change from what I was working on in 2007 is that back then we were dealing with the unit of speed as a meter per minute. We considered that if a boat was gaining 3 meters per minute [compared to a training partner, for example], it was super quick. It’s much more exciting for us now because we are dealing with massive boat speeds and speed differences. Instead of 3 meters per minute, we are talking about 40, 50, or 80 meters per minute. These are massive differences because there is a lot to gain.

Did you bring much from the last campaign, with the 90-foot trimaran, to the current campaign?

JO: Same as with the ORMA [the French offshore multihull circuit that spawned so much innovation from 1996 through 2007]. We spent a lot of time on the big trimaran and studied things a lot more carefully than in the past, so we have a lot of knowledge on the multihulls. Since the 33rd America’s Cup, I think multihull design has taken a new step forward. There’s much more work involved, and for us, we had done the wing sail before, so we knew where to go with that.

Is the wing more important that the foils on the 72s?

JO: No. You need to consider that the foils are now the main driver of performance on these boats. It’s critical to have it right. Last Cup I was a wing designer, and then everybody believed that the wing was the key but that’s not true. The reality is that on this boat, the multihull, we try to minimize the drag. That’s the goal overall. Where you can really make big gains is under the water, and you really need to have it correct. The foils and the windage are two areas where you have to focus because boats are going 40 knots, and the faster you go [the more] you’re going to create drag. The most efficient way to do that is to lift the boat to reduce the volume of the floats, so you need to lift your boat out of the water. You can do that with foils, but you can’t do that with the wing because it is vertical.

You trained with Juan Kouyoumdjian. Are you surprised Artemis Racing [where Kouyoumdjian is the lead designer] didn’t adopt foils earlier?

JO: First it’s a multihull, and these guys have never designed a multihull before; it’s a quite different exercise. What I understand from them is that they didn’t evaluate the value of lifting your boat; it’s not whether you are flying or not, it’s the gain of reducing the amount of volume you’ve got under the water. There are some key areas where you can gain performance, and you need to identify these areas and focus on those. It’s surprising to do this change now, but you have to do it. It’s good that they’ve realized that and can change now, rather than in July. These are super complex boats. There are a lot of parameters involved, and it’s really a complex equation. I believe that if you are not that familiar with multihulls, it’s not easy to get it right the first time.

It’s been suggested that summer conditions on San Francisco Bay may not be conducive to foiling—fast boats, short courses, big breeze, significant current. What do you think?

JO: As always when you design a boat, compromise is wind-related: light versus strong, etc. The aim is not to “fly” at any price; our goal is to reduce the drag on the boat. For particular conditions and a particular moment of the race, it’s going to be a consequence to foil because we try to reduce the drag and foiling is the consequence of this particular design package. In some conditions the best set-up is to fly, but if you end up with the wrong angle and you go too high or too deep, it’s not adapted to the race. You may be fast but you need to be fast in the correct direction. Perhaps with Artemis, the call was that it was never going to be efficient. If you look at the boats right now, ETNZ is going to be very good in very strong winds, Artemis will be good in light air. The problem is we really never know what the wind is going to be for racing.

What’s the best scenario for the foils to work optimally?

JO: There are two parameters: the wind strength, and if you are upwind, downwind, or reaching. There’s an optimum shape depending on the conditions, and when you want to lift your boat out of the water you need to have a certain boat speed to do it, so you need to have enough wind to reach these boat speeds. You’re going to reach these boat speeds mostly downwind or reaching, so I don’t see there’ll be any boats flying upwind because you don’t go fast enough.

How many sets of foils are you allowed?

JO: The Protocol allows us to build 10 boards maximum. As usual in the design world, you can get good boards for light air, good boards for flying, good ones for upwind, good ones for downwind, etc. There are multiple combinations. In a perfect world, if you know the conditions in advance, you can choose the best set for your race. In reality, it is a matter of range: which set gives you the wider range regarding the conditions that you will very likely get during the race. Each team will probably end up with one or two good sets and will choose few days in advance which one is the best for the coming races.

How have you observed the transition to the focus on foils?

JO: I’ve been working on multihulls for a long time, even before the Cup. I’ve been working on the ORMA 60 and have done a lot of work since 2001 with Michel Kermarec, who is the main foil designer here at Oracle. Foils have always been a big focus. Using the sails as an example, the sailors have always been very involved in the sail design as many used to be sail designers and sail trimmers so there is a strong connection. But, on the hydro part of it—the foils—because the sailors don’t see the foils, they have less implication. That’s started to change because everybody understands the importance of this design, so there’s more interaction. We’ve seen it on the dinghies, the catamarans, the Moth; there’s a strong focus on the foil because there’s a lot to gain here. We need to see that as a big driver; what you do with your sails, you do the same underwater. It’s an equivalent amount of work that you need to do in the package.

How have you trained the sailors to use the foils?

JO: We give them targets, for example, when they go sailing, we say in this condition you need to have this angle, trim it this way. We give them some numbers to start with, which they usually follow, then they will come back to us with feedback. We have a constant communication with the crew on this. It’s very important, and we don’t always speak the same language. As soon as you put an equation or formula on the table you just lose your audience, so you need to find a way to talk to them. You need to convince them that your design is correct and explain to them that this is the design and how you can trim it. It’s kind of like a user guide that we give them. It’s complex because you have a lot of parameters to play with.

What’s your impression of the 72?

JO: They’re amazing boats and very impressive machines. They are much more powerful than the ORMA 60s, for example. The development is much more refined, much more accurate.

What’s your day-to-day routine?

JO: It’s busy in phases mostly. You’re super busy when you need to finalize the boat, the shapes. In my case it’s the shapes. I do performance predictions; you’re constantly using them as tools to predict performance when we need to design a new shape, so it’s kind of busy right now. I’m not personally involved with the prediction itself, but when the boat is sailing it’s very busy because you collect data so that you can validate the assumptions you did months before when you were designing the shape. There is a lot of value when the boat is sailing because you’re getting feedback from the sailors, and it’ll be like this until the end. When you see something happening on the water we need to be able to explain it: why it's faster, why it's slower, why you need “this” set up, so we are very busy with that.

Who drives the decision to design a new shape?

JO: Michel K is responsible for the new shapes, but it’s actually very simple: We have a certain amount of money for the campaign; we have a deadline, Sept. 13. With the budget we decide we’re going to build X boats, so we’ve got a deadline for the boat and the shapes--that’s how it essentially works. You will give your shape with your base knowledge at this stage. Obviously we have much more knowledge at this point than we did a year ago with the first boat. You’re constantly processing new information.

Boat 2 won’t be out of the shed until April; do you feel like you’re behind schedule?

JO: Not really. We had a tough time with the capsize, but I think we took a lot of positive from that, and I think we are stronger now than we were because we know the limits, and we know what happened and were able to react. I’m happy with where we are now. I’m very confident that we have the correct boat.

By Michelle Slade, originally published at: http://www.sailingworld.com/blogs/racing/americas-cup/foil-focused