Design Optimization of Subcavitating Hydrofoils for America's Cup Class Yachts

To understand the latest design in the America's Cup, it is essential to recognize its innovative features. This design, utilized in the last two cycles of the America's Cup, represents a significant advancement in sailing technology. Previously, catamarans were favored for their speed, characterized by narrow hulls and foils that provided lift. However, these vessels were wide and lacked the elegance of the current design.

The current model is a monohull equipped with two large foil arms that adjust based on the wind direction. When the wind comes from one side, one foil is submerged while the other remains above water. The entire boat is supported by these foils, with the vertical force generated by the foils counterbalancing the boat's weight. While there is a rudder and a foil for trimming, their contribution to force is minimal compared to the main foils.

Each foil is constructed from solid steel, weighing 1.5 tons, which creates a substantial moment to counterbalance the force of the sail. This design allows the boat to maintain a straight course rather than leaning, significantly enhancing efficiency. Despite their high efficiency, these vessels are complex to operate and design, requiring extensive training in both aerodynamic and hydrodynamic forces.

To address these complexities, we focused on a small portion of the overall design, specifically the two foils. For this analysis, we employed the Mach framework, a tool developed within my team, which I previously discussed during the 85th anniversary of Professor Jason.