When Emirates Team New Zealand defended and retained the America’s Cup in March 2021, the team counted Ansys simulation among its preferred engineering tools. Te Rehuta, which means “spirit of the ocean” in Maori, was officially christened in November 2020 as the ETNZ entry for the 36th America’s Cup. The team has a long relationship with Ansys. For this campaign, Senior Consulting Engineer Douglas Weber-Steinhaus spent time embedded in the group. Engineering.com had a chance to talk with Douglas about his experience in the 36th cup campaign, how engineering simulation helps a team’s performance and facing a global pandemic in New Zealand.
Ansys’ History with America’s Cup
The first America’s Cup occurred in 1851, and the organization calls itself the oldest trophy in international sport, beating the Olympics by 45 years. Team New Zealand has worked directly with Ansys as far back as the 1999 contest, and Weber-Steinhaus said that Aero Coordinator Steve Collie and other team members have been using the software for decades. The 2017 Bermuda campaign saw the team using structural simulation along with fluid dynamics to build their models.
Douglas comes from the team that worked on the development of Ansys Composite PrepPost (ACP), and some of the work on that tool came directly from the company’s involvement with the cup teams. After a meeting discussing the new features of ACP, Team New Zealand expressed a need for an engineer to help with composite analysis. It gave Douglas the chance to go to Auckland and work for six months.
He said that the opportunity to work with ETNZ was great and that New Zealand may have been the best place to wait out a pandemic. Two regattas planned in Italy and England were scrapped due to COVID-19 concerns, and a pre-Christmas race was one of the very first times that actual boats could be officially tested in water.
Innovation through simulation. (Video courtesy Leap Australia.)
America’s Cup Has New Rules That Focus on Simulation
Weber-Steinhaus said that America’s Cup teams are very strong technological partners to work with, and teams have more than two decades of experience in simulation. Previous versions of the cup tested different sail configurations with wind tunnels, computational fluid dynamics calculations and head-to-head testing in the water. Today’s teams have a much tighter focus on time, and computational testing is done more often than water testing or physical prototypes.
ETNZ won the 35th cup and the right to create the charter for this 36th competition, and the team wrote the rules in a way that favors simulation. The 2021 rules stated that no wind tunnel or tow tank testing could be used. Prototype build was allowed, but the prototypes were required to be half-scale models.
These rules shifted focus from a prototype build and iterative design mentality to a simulation and computation approach to refine the sail and hull designs before any parts were fabricated.
Douglas said that the new rules for construction changed the way simulation has to be run—normal displacement modes of a hull in the water can shift from a fluid dynamics problem to an aerodynamics simulation when the foils are in the water and the hull acts as a fuselage.
Team New Zealand has a proprietary simulator called the Velocity Prediction Program (VPP) that lets the team try out different versions of foils and hulls. This tool helped ETNZ develop a monohull structure with foils and build a rule from that data to give them a competitive advantage.
For Weber-Steinhaus, it was exactly what Ansys wants to see—their tools used at all stages of a product development cycle. Team New Zealand is using standard Ansys software without any tweaks, but the Ansys team has met with the teams to get input for future developments.
Simulation Is a Tool for Success at America’s Cup
One of the most interesting parts of the simulation was the wind speed data. How do teams get historical data for wind speeds and direction? Speaking from experience, with hot air balloon teams, the one thing that’s constantly beat into team members’ heads is to not count on the wind. Teams can have a good idea of where the wind is coming from and how fast it’s coming, but until they’re up in the sky in the middle of it, they won’t really truly know.
Douglas talked about Team New Zealand’s meteorological weather expert who has historical knowledge of wind data in general but also good data for Auckland’s Waitemata Harbour. Predicting the wind and choosing the right sails definitely gives a team a competitive advantage. The other side of the equation, he said, was the foils. Teams need to declare which foils will be used six days in advance of a race, and that is the limit of a wind prediction window.
When a team is involved in a cup campaign, the full experience can feel like a project management exercise. Teams are in tight developmental windows and work to optimize the time and money spent while fielding the best boat possible. Bringing a boat to competition that isn’t as fast as the competitors will give a team a fundamental disadvantage. Physical prototyping has been a stumbling block for timing in the past, but different configurations can now be tested in a virtual environment to get better answers more quickly.
Benchmark data is also notoriously difficult because actual physical tests are done with specific water and wind conditions. Thus, bringing a different sail or hull configuration an hour or a day later might not be using the same conditions for testing. The benefit of simulation is that the simulation environment is held constant over multiple tests, giving a straight comparison to different shapes and arrangements.
Over the past few decades, there has been a visual shift of focus from physical testing to simulation but also growing confidence in the results teams receive from virtual calculations.
Douglas also pointed out that cup teams aren’t focused as much on top speed like a drag race but the fastest lap time over a range of speeds. Figuring out how to get the best possible performance over the full lap both with and against the wind gives a team the best results.
Simulation can’t be a perfect reflection of reality, but it can come very, very close. The sailors on Team New Zealand were well-versed in using engineering judgment for which details needed to be the most accurate and required the most time investments and which details could afford to be a little looser.
Watching America’s Cup
Although Weber-Steinhaus wasn’t physically present for the races in Auckland, he was able to wake up at 4:00 a.m. and watch the contests. He was pleased to see that some of the parts he worked on made it to the final iteration of the boats that competed for the cup.
Among the various races, this one from the Day 7 highlights provides excellent insight into the huge amounts of technology that goes into the competitions, from the instantaneous speeds shown on the screens to the courses superimposed on the water to the support boats following the competition boats.
Highlights of Day 7 of the 36th America’s Cup. (Video courtesy of America’s Cup.)
Engineers can be proud that their simulation tools are helping teams like Emirates Team New Zealand squeeze out the best competitive advantages possible. As ETNZ wins by getting a competitive advantage, Ansys gains knowledge about how its software is used out in the world and has a great story to tell about its tool embedded into a full-design process.