PIONEERING INNOVATION BRINGS AEROSPACE-GRADE CARBON TO THE WORLD OF SAILING: 3Di RAW 900

Emirates Team New Zealand and North Sails spent 18 months developing a material no one had ever put in a sail. Then they won the America's Cup with it.

Mankind’s greatest innovations are often borne from a simple question. For the scientists and engineers operating deep inside the Emirates Team New Zealand America’s Cup matrix, the question posited three years ago was indeed a rudimentary one that spawned the most important sail development of the 37th America’s Cup cycle. It happened during one of the countless team meetings, 18 months out from the team’s first race in Barcelona. A sailor raised his hand and asked, “Is there a way to take this even further?” What they were really seeking was a material that was lighter and stiffer than what they were already using in their 3Di sails—specifically, a high‑performance carbon fiber that could unlock the next level of performance.  

Burns Fallow, North Sails’ designer embedded with the team, pulled the man with the answer into the meeting. Dr. Chris Hickey, the team’s materials and composites specialist, quickly identified two or three candidate fibers that would be allowed within the technical rules. "The 3Di 880 product they'd been using was significantly below the top end of the AC materials rule limits, actually more than 20% below, according to Fallow. In the Cup world, that’s a gaping opportunity, and even more reason to work toward something better. That something better is now the North Sails flagship 3Di RAW 900 cloth, what Paul Westlake, Grand Prix Sales Leader at North Sails, considers to be the Holy Grail of high-performance sailing.  

But we’re getting ahead of the story. Let’s pause for a moment to talk layman’s carbon, starting with “modulus.” Modulus measures stiffness: how much a material resists stretching under load, and there are several grades when it comes to carbon. “Standard modulus" is the most common grade of carbon fiber that you will find in golf shafts, bikes, automobiles and so much more. It is plenty strong, stiff, light, and relatively inexpensive. The AC75 rules, however, allow teams to tap into the next level with what’s called “intermediate modulus” which can be used in both the sails and the hull and is stiffer and stronger than standard modulus. Next comes high‑modulus carbon, which is permitted only in the mast and is commonly used in mast construction.

For sail materials, therefore, teams are forced to play in the intermediate space, so the challenge for Hickey was to source a carbon grade at the upper limit allowed, but more importantly, define a variety of intermediate-modulus fiber that would work with North’s existing 3Di manufacturing process.

Hickey’s recommendation was ultimately a grade called T800, manufactured by Toray Composite in Decatur, Alabama, one of the world’s largest producers of carbon-fiber materials. Toray’s Mathew Thompson, PhD, who wasn’t involved with the Emirates Team New Zealand project, says T800’s application to high-tech sails makes perfect sense. Its high strength-to-weight and stiffness-to-weight is ideal for stiffness critical structures like airplane wings and fuselages where you don’t want much deflection or shape change. It’s Toray’s flagship aerospace-grade fiber, used on the Boeing 787 Dreamliner, for high-end automotive and racing teams, for defense and space travel, including the incredible Artemis II lunar mission. T800, Thompson says, is less brittle, easier to work with, and more forgiving in processing.  

“Typically, we talk about strength to weight ratio or stiffness to weight ratio,” Thompson says. “Sails are going to be stiffness critical; you don’t want the sail to change shape too much. That would be stiffness critical.”  

For Fallow, T800’s adaptability to the 3Di process and existing machinery was the critical factor for Emirates Team New Zealand and North Sails embarking on an all-hands-on R&D initiative set against an 18-month countdown from the Cup.  

“This is an incredibly tight timeline,” Fallow says, “to use a new carbon material which has never been used in the yacht world before.” 

There is a myriad of challenges around introducing a different material into the 3Di process, Hickey says. “You have to ensure that you can maintain the same level of quality in the tape, that the fibers are really well spread and impregnated.”  

Easier said than done—as it should be at the bleeding edge. Fallow says there were a few hurdles to bringing T800 from a promising fiber to a reliable 3Di reality, starting with fitting the fibers to existing machinery. The T800 is a much larger yarn, about twice the size of their normal carbon, he says. Traditional 3Di tapes are made by feeding as many as 30 yarns and spreading them across a 600-mm tape. “Switching from 12 small yarns to six big yarns risked uneven spread, heavy tapes, and loss of design flexibility.”  

The team in Minden, Nevada, led by Peter Jahrei, worked hard to overcome this barrier. With due diligence they got it to run through the machines without major hardware changes; it spread well in the process and adhered properly with the standard resin brew. “In spite of the fact that this T800 yarn was really large as far as yarns go, it actually worked really,” Fallow says. “And that side of things was pretty easy actually; it worked pretty well.”  

Now, let the testing commence.   

Once confident to push ahead with their top-secret T800 blend, ETNZ ordered raw materials in July 2023 and North specialists conducted their first tests in Minden, two months later. To get more data and confidence, Emirates Team New Zealand also triggered their own parallel testing in New Zealand. 

Once the project got going, it was less than a month after ordering and getting the material from Toray, says Dr. Stephen Collie, the Aerodynamics Engineer who manages Emirates Team New Zealand’s rig and sail program. The boat’s “aero package” is his domain. “The process of making the tape and then curing took a couple of weeks. At the same time, Burns was designing two different sails—one with this product and one with the original. When we got to the last test results [saying], ‘Yeah, we’re confident this is a better for the intended use,’ he pushed the button and sent it, and the rest is history.” 

Tests of the T800 3Di material include a baseline tensile test, essentially taking fresh material and pulling it to measure stiffness and resistance to stretch (“modulus” being the technical term). Second is fatigue testing, where strips of the material run back and forth through rollers for hundreds or thousands of cycles and then re-tested in tension to see how much stiffness they lose with “normal” wear. Third is fold testing, where samples are repeatedly hard folded through 180 degrees to simulate aggressive handling and creasing. Those pieces are then pulled again to see how much damage that sort of abuse does. For the T800, Fallows says, they compared all the results directly against 15 plus years of data from their standard 3Di carbon sails. He was plenty happy with the data plot curves.  

After three weeks of testing, they were confident enough to submit sail designs for their AC40 testing platform (in LEQ12 configuration), and by November 2023, the sailing team was doing dry laps, growing ever more confident that the sails were behaving as designed.

February 2024, Fallows says, was the go/no-go window. With the big AC75 launching in April 2024, they had to decide whether to commit a rules-limited inventory of six AC75 mainsails with this new material. That’s a pricy high stakes decision off the back of only a few months of testing and one season on the little boat. “If the first one of those [mainsails] is a disaster, you’ve really shot yourself in the foot,” Fallows says. “If you have to essentially throw one of those away because of a bad call, that’s really bad.”

Ring, ring went the telephone in Minden. And into the sailors’ hands—or at least their sail control modules on the AC75, went the most sophisticated carbon sails they, and their LIDAR eyes, had ever trimmed. Sails that barely stretch when loaded or filled with apparent wind give the sailors a “locked in” design shape. Less energy is lost to the sail deforming under load, and that power goes straight into driving the boat. Plus, there’s an astonishing scale of versatility built into the sails. The AC75s sail through an apparent wind range, from trying to foil in less than 7 knots of wind to surviving into 20 plus. T800’s stiffness allows the trimmers to pull much harder on corners (think Cunningham, vang and outhaul) without the sail losing its designed structure.  

“The actual range of depth we go through in these sails is much more than on any conventional boat,” Fallows says. “We end up pulling on corners so hard to extract every last bit of range we can.”  

The boatbuilders and engineers especially appreciate being able to take advantage of the weight savings of the 3Di, utilizing the new T800 fiber. Every gram saved aloft can always be put to better use. “If we could build a sail which was five kilograms lighter, that’s five kilograms of carbon that can go somewhere else in the boat,” Fallow says. “Emirates Team New Zealand’s lighter sails held their shape under insane loads, could be trimmed aggressively across an insane wind range, and they weren’t discarded into the dumpster after a short campaign. In fact, Emirates Team New Zealand is currently using them as they develop their next quiver for AC38 in Naples in 2027.  

Westlake is confident that North’s T800-based 3Di RAW 900, which is now available to all the current America’s Cup teams and grand prix programs, is a groundbreaking step, not just an incremental tweak to the 3Di line. “You’re getting more range out of the sail,” he says. “The more racing life you can get out of any given sail, is added value, and that’s very important for the continuation of the sport and for the strength of the sport.”  

Emirates Team New Zealand’s gamble on T800 delivered exactly what they needed: a higher modulus 3Di structure that stayed within the AC75 rule and obviously contributed to the drubbing of their challengers in Barcelona. But what if today one of their sailors asked the same simple question; is there something better?   

“Not at the moment,” Collie says. “They’re knocking on the locked door of the AC75 rule. With the current manufacturing processes, this is probably the pinnacle. The [AC75] rule is kind of designed around that. It doesn’t want us to push into higher modulus materials that would be more expensive and more prone to degradation and failure. The rule sets it all at what is quite a practical point for whatever the current fibers are.”

In other words, with T800 and 3Di RAW 900, we’re at the rule-intended ceiling of sensible, durable performance in grand-prix sails. Another leap would require new manufacturing techniques or changes to the class rules. Next question.