Using simulation to reduce development costs and power sustainable support vessels for America’s Cup competitors

Helping America’s Cup entrants succeed

Caponnetto Hueber provides innovative naval architecture solutions, fluid dynamics services and products for the maritime industry. The company employs cutting-edge methodologies and tools for naval architects, yacht designers, startups, shipyards and ship owners to improve design, performance and efficiency and reduce energy consumption and emissions. For over two decades, Mario Caponnetto and Francis Hueber have supported teams competing in the America’s Cup, a world-famous boat race that is the oldest international competition in any sport. In 2010 and 2013, they worked with the teams that won the competition.

Since 2010, the average speed of the boats has increased from around 10 knots, 20 kilometers per hour (kph) to 50 knots (92kph). The latest regulations require each team to have a hydrogen-powered support vessel (HSV) with a range of 180 nautical miles that can match the speed of the competing yachts. If the catamaran did not meet all the specifications, it would result in the team having points deducted in the final standings, which could make the difference between winning and losing.

With the fuel cell, battery and motor design fixed and unchangeable, they designed and optimized the hydrofoils to reach the speed and range targets. Caponnetto Hueber used Simcenter™ software, which is part of the Siemens Xcelerator business platform for software, hardware and services, to maximize efficiency and performance.

Rendering of HSV with free surface deformation.

Improving propeller design

Meeting the sustainability requirements of the support boat made reaching the minimum speed even more challenging. The team not only needed to generate enough power, but it also had to account for weight and space issues.

“Hydrogen itself is light, but carrying 4 kilos takes up a lot of space as it’s stored at high pressure and must be vented to ensure safety,” explains Caponnetto, cofounder and technical director of Caponnetto Hueber. “We had to accommodate this and the weight of the battery and also allow for potential changes if they decided that any components needed to be moved.”

Caponnetto identified the propeller design as the key to realizing the biggest efficiency improvements. “Cavitation is when water boils and vaporizes due to low pressure on the blade’s surface, which significantly reduces propeller efficiency and can lead to serious damage,” he says. “To overcome this, we designed a super-cavitating propeller from scratch.”

The time-accurate propeller behind the computation. This model features the VOF model for the free surface and the cavitation model for the vapor on the foils and propeller.

Speeding up iterations with simulation

Each iteration of a propeller design is usually tested in a towing tank, but this process can take years, which was time the firm did not have. Each cycle of the America’s Cup lasts three years, and then specifications are changed and new boats are built. Traditional testing would not have delivered results in time for this competition.

Therefore, Caponnetto Hueber built a digital twin of the propeller and simulated its performance with Simcenter™ STAR-CCM+™ software, Siemens Digital Industries Software’s computational fluid dynamics (CFD) solution. This allowed engineers to iterate much faster, experimenting with different designs as they reviewed the results of each simulation.

Miguel Brito, CFD engineer, says the most important factor was to ensure the accuracy of the cavitation prediction: “First we had to carry out takeoff and foiling analysis to calculate the resistance from the boat. Then we separately analyzed the performance of the propeller and combined both to get a reliable prediction of power output.”

Safety was at the forefront of the engineers’ minds and could not be compromised to meet the challenging targets. “We also modeled the possibility of hydrogen leaks during operation,” says Brito.

“The simulation results confirmed that if there was a leak, it wouldn’t cause a dangerous explosion.”

Analysis of the hydrogen tank compartment ventilation.

Rapidly achieving exceptional results

Once the team was confident their design would reach the required speed, the propeller was built, and full sea trials were carried out. These trials confirmed the vessel could reach a top speed of 50.8 knots, exceeding the minimum requirement and ensuring that no penalties would be incurred.

Without simulation, it would not have been possible to complete the project within the current cycle of the competition. “In the past, we spent up to two years sending designs back and forth, then building, transporting and testing prototypes,” says Caponnetto. “We used Simcenter to achieve the same results in just two months and 10 times cheaper.”

Caponnetto also highlights the open-source nature of Simcenter as an advantage. “Thankfully, Simcenter is designed to integrate with other solutions, so we were able to easily add our existing customized routines rather than having to spend a long time rewriting it.”

These significant time and money savings weren’t the only benefit of using simulation. “Even if you could test as quickly and cheaply in the towing tank, it’s not a fully accurate test,” explains Caponnetto. “It uses a scale model rather than full size. We do our best to replicate the physics, but it can never be quite the same. So in this respect, the CFD simulation is at full scale and is more accurate. The multiphysics modeling capabilities of Simcenter STAR-CCM+ are incredibly realistic. It gives a great illustration of the flow around the propeller to see exactly what is happening, which you can’t reproduce with the towing tank. This visualization gives much better insight into how to adapt designs for performance improvements.”

Free surface visualization in Simcenter STAR-CCM+.

A bright future

Caponnetto is confident that Simcenter will continue to be a vital tool in the marine industry and is looking forward to new developments that will make it even faster and better. “Increasing the use of GPUs will speed up computation further,” he says. “There is great potential for artificial intelligence to improve simulation and speed up optimization. It’s good to see that Siemens is investing in these technologies and I’m excited to see how they can help us.”