America’s Cup: Geeks rule the world

Published on November 25th, 2022

Unique to the 37th America’s Cup has been the AC40 boat, essentially a scaled down version of the AC75 boats to be used in the 2024 event. The boat is freshly designed by the Kiwi defender, intended as a cost-saving platform for testing and racing. Here’s an update from the New Zealand camp:

Four days ago, Emirates Team New Zealand buried the bow of their AC40 while testing in waves on Auckland’s Hauraki Gulf, which resulted in damage to the forward sections of the hull and deck structure.

While the on-water team was recovering the yacht and returning to dock, the team’s engineers immediately began reviewing onboard data to identify the root cause of the issue.

“The first things we look at in this type of dynamic event are the accelerations and rotation rates that come from yacht’s inertial measurement unit (IMU),” explained Jamie Timms, Emirates Team New Zealand Structural Engineer.

“These readings allow us to infer the magnitude of the hydrodynamic loads on the hull structure, which we can then input into our structural simulations to estimate the stress state and structural margins of safety. We also use the data to validate our fluid dynamics simulations of high velocity hull impacts.


“During the 36th America’s Cup, we captured and catalogued the dynamics of every major event across the three yachts we sailed in that campaign and we enveloped those, with additional margin, to define the load cases for the AC40.

“Over the first 18 days of sailing the AC40, we’d seen a couple of events that generated large impacts. These had been lining up with our design load cases and the hull structure was performing as expected. However, this latest event saw accelerations that were far beyond all our previous records.


“The figures below compare the longitudinal and lateral decelerations from the AC40 crash against the largest event seen by Te Rehutai, the team’s AC75 from the last America’s Cup (pictured above). Not only did we see longitudinal decelerations 70% higher than the previous worst-case, but this was coupled with a simultaneous lateral loading of similar magnitude – the yacht came to a complete stop and yawed 90 degrees in just over a second.

“We believe it was this combined load state that led to an initial failure of the foredeck sandwich panel. The damage we saw in the hull and partial detachment of the bow structure is likely a consequence of the compromised deck panel, rather than a root cause.”

With this new data in hand, the team’s engineers have designed an internal structure upgrade package that will be rolled into all current and future AC40 yachts.

“Throughout the development of this class, we’ve seen the yachts become increasingly dynamic as the performance of the yacht and the skills of the sailors grows. As with any high-performance craft, there is a constant balance between reducing mass and ensuring reliability and safety, and as our understanding of the class grows, we evolve our approach to maintain that balance.

“This additional structure will restore full structural margins for the uprated load cases and allow the sailors to push the performance limits of the class safely and with confidence.”

The internal structure upgrade package will be built by McConaghy’s, who are building the fleet of AC40’s.

“The good news is there will be no change to the delivery schedule to the remaining AC40s currently in build and the bow upgrade package will be shortly sent from the McConaghy yard for retro fitting to the three AC40s that have already been delivered.”

Team New Zealand has the first boat, the second boat was sent to INEOS Britannia, with the third boat going to the Kiwi defender.

Following the publication of the AC37 Protocol and AC75 Class Rule on November 17, 2021, the AC75 Class Rule and AC Technical Regulations were finalized on March 17, 2022. The entry period opened December 1, 2021 and runs until July 31, 2022, but late entries for the 37th America’s Cup may be accepted until May 31, 2023. The Defender was to announce the Match Venue on September 17, 2021 but postponed the venue reveal, confirming it would be Barcelona on March 30, 2022. The 37th America’s Cup will be held in September/October 2024.

Teams revealed to challenge defender Emirates Team New Zealand (NZL):
INEOS Britannia (GBR)
Alinghi Red Bull Racing (SUI)
Luna Rossa Prada Pirelli Team (ITA)
NYYC American Magic (USA)

Additional details:

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