An In-Depth Exploration of AC75 Masts and Rigging Systems

Inside the America’s Cup: A Closer Look at AC75 Masts and Rigging

As the Round Robins progress and Barcelona delivers, the AC75 fleet showcases impressive speed.

The competitive performance can be attributed to several recent technical innovations, including cyclors, enhanced foil designs, aerodynamic improvements, and advanced control systems. However, one area that may not receive as much attention is the rig and rigging design. Since the introduction of composite materials into the America’s Cup, rigging has played a crucial role in team performance on the water.

Class Rules

The AC75 class rules set forth specific one-design aspects for mast design and construction. These rules dictate the shape (D-section) and dimensions of the mast tube. Additionally, they specify requirements for carbon fibre, including fibre modulus, areal weight, and resin content. The rules also define the geometry and materials of fittings, such as shrouds and spreaders, limit mast rotation to 45°, and set guidelines for the mast rotation ball’s height in relation to the waterline.

Mast Rotation

Teams can enhance power and performance through control of the 45° mast rotation. Notably, all AC37 participants have chosen North Sails due to the performance of their Helix structured luff technology. This innovative design redefines sail capabilities by optimizing power potential through controlled load distribution, promoting a positive sail shape.

With a mast design that adapts to sailing conditions by rotating precisely to maximize wind efficiency, the synergy between masts and sails has become increasingly intertwined in the AC75 class.

Thickness & Stiffness

Mast bend also significantly influences sail shape. While the basic laminate and core requirements are defined in the AC37 class rules, teams have the opportunity to modify their masts by adding more laminate for increased stiffness or altering the deflection response. This flexibility allows teams to optimize mast performance to meet the specific needs of their sail designs.

No Backstay

In a significant departure from previous designs, AC37 has introduced a fully one-design rigging component supplied by Future Fibres. A notable change is the removal of the backstay, which impacts how mast bend is controlled. As a result, the management of mast bend is now primarily achieved through sail controls. This alteration has increased loads on shrouds, leading to the need for larger cap shrouds and upgraded jib locks from 5t to 8t. Additionally, as mandated by AC36 rules, Future Fibres rigging packages are equipped with integrated fibre optic load monitoring for performance analysis.

Looking Ahead

Various design factors, such as luff tracks, batten stiffness, halyard locks, and mainsail controls, are under the purview of team designers. The unfolding events of the 37th America’s Cup will reveal which technological advancements will influence performance. However, one thing is certain: innovations in this prestigious competition will resonate throughout the sailing industry for years to come.

As Southern Spars’ General Manager Mark Hauser notes, “we are immensely proud of our close partnerships with the teams, committing ourselves to the pursuit of excellence. Innovations in the Cup reverberate around the industry for years thereafter, and we are proud to be leading the charge with the world’s most elite sailing teams.”