Precision Engineering: The Evolution of Foil Flow
The pursuit of speed in the America’s Cup is increasingly a game of millimeters. Recent testing by Emirates Team New Zealand on their AC75, Taihoro, highlights a shift toward hyper-specific foil adjustments to optimize water flow.
One notable development is the integration of little vertical fins fitted mid-section on wing foils. These components are designed to align cross-sectional flows over the wing, reducing turbulence and increasing efficiency.
To validate these adjustments, teams are relying on Pitot Tubes. These sensors accurately measure the speed of water passing over the wings, allowing performance analysts to turn raw telemetry into actionable design changes in real-time.
The Risk of Legacy Hardware in High-Performance Sailing
As yachts push the boundaries of physics, the margin for equipment failure narrows. A recent incident where a jib tack blew out during modest breeze testing serves as a critical case study in sail durability.
Analysis suggests that using legacy sails—such as those from the 2024 campaign—can introduce vulnerabilities when paired with newer, more powerful hull and foil configurations. The immense loads generated by modern AC75s can easily exceed the tolerances of older materials.
However, structural safeguards are evolving. The use of an independent forestay is a vital design trend, ensuring that a sail failure does not result in catastrophic rig damage, allowing teams to resume testing quickly after a setback.
Data-Centric Training Under Strict Limitations
The methodology of America’s Cup preparation is shifting from “quantity of hours” to “quality of data.” For the upcoming 38th America’s Cup in Naples, teams face tight restrictions on sailing time.
Emirates Team New Zealand, for example, is limited to just 45 sailing days on the boat between the current phase and January 2027. This restriction forces a strategic pivot toward longer, high-intensity sessions in specific weather windows.
This “data-first” approach involves long runs—similar to Olympic dinghy sailing—to feed massive amounts of information back to analysts on the chase boat. Every outing is now a calculated mission to eke out every possible advantage in pitch angles and exit speeds.
Mastering the ‘Carve Gybe’
A key focus of this data-driven testing is the perfection of “carve gybes” downwind. By optimizing these maneuvers, teams can maintain higher exit speeds, which is often the deciding factor in close-quarters racing.
Crew Ergonomics and Onboard Accessibility
Innovation isn’t limited to the foils and sails; it extends to how the crew interacts with the machine. The complexity of the AC75 requires sailors to access areas of the boat that were previously unreachable during active sailing.
The introduction of “soft ladders” allows crew members to clamber down the side of the wingfoil to inspect equipment or make adjustments. This focus on ergonomics reduces the time spent on maintenance and increases the safety of the crew during commissioning phases.
For more on the technical specifications of the latest yachts, spot our AC75 Technical Guide or visit the official America’s Cup website.
Frequently Asked Questions
What is the purpose of the vertical fins on the AC75 foils?
They are used to align the cross-sectional flows of water over the wing, which improves stability and efficiency.
Why is the sailing time limited to 45 days?
Current regulations for the 38th America’s Cup tightly restrict the amount of time teams can spend sailing their AC75s to ensure a level playing field and manage costs.
What happens if a jib fails on an AC75?
Since these boats utilize an independent forestay, a jib failure typically does not cause structural damage to the rig.
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