Challengers | Ep 06 The Build

The road to the 38th America's Cup isn't only shaped on the water. Behind closed doors in Portsmouth, the next chapter of GB1's campaign is already taking shape.

Episode six of Challengers takes viewers inside the design and build programme powering the team's AC75 campaign, revealing the engineering, innovation and relentless attention to detail required to prepare one of the world's most advanced racing yachts.

Following the first Preliminary Regatta, the sailing squad returns its focus to performance on the water while, behind the scenes, work intensifies on transforming the team's AC75 ahead of its planned relaunch later this year.

Technical Director Nick Holroyd leads a design group of around 35 specialists, bringing together software engineers, computational fluid dynamics experts, mechanical engineers and performance modellers to develop every aspect of the boat.

"The range of skills required within our design group to execute these boats is quite remarkable," Holroyd explains.

With more than 15 years of America's Cup design experience, Holroyd knows success comes from balancing innovation with precision. Every design decision must deliver performance while ensuring the boat is ready on schedule for testing ahead of racing in 2027.

One of the biggest challenges facing the team is adapting the existing AC75 to meet the new class rules. Rather than building an entirely new yacht, teams are modifying their current race boats, making every design decision count.

The most visible change will be the redesigned cockpit configuration, reducing the sailing crew from eight to five while introducing a sixth position for a guest racer. Beneath the surface, however, the work is far more extensive.

Every system inside the boat—from its electrical and hydraulic networks to onboard computers—must be removed, redesigned and reinstalled. At the same time, engineers continue refining the foils, sails and control systems, searching for the smallest performance gains.

"Fundamentally, we have to keep making the boats more efficient," says Holroyd. "If we can reduce drag by even a small amount, we're going faster."

The episode also follows CEO Ian Walker as he visits the team's AC75 during its transformation.

Walking through the stripped-out interior, Walker sees first-hand the scale of the rebuild as the boat is cut apart before being reconstructed to the latest design specifications.

"It's always a balancing act in the America's Cup," Walker says. "The designers always want more time, and the sailors always want more sailing time. In the middle you've got the boat builders."

Finding that balance is one of the defining challenges of every America's Cup campaign. Delay the design too long and the sailors lose valuable training time. Commit too early and the team risks missing out on performance gains that could prove decisive in Naples.

With rival teams already beginning to relaunch their AC75s, GB1 continues to monitor developments through the shared reconnaissance programme while remaining focused on its own pathway.

"We don't know exactly what the other teams are doing," explains the sailing team. "Focusing on ourselves is key."

The episode offers a rare insight into the unseen side of an America's Cup campaign, where months of engineering, analysis and craftsmanship lay the foundations for success long before the first race begins.

As work continues around the clock, every decision is made with one goal in mind: launching a faster, more efficient AC75 capable of challenging for sailing's oldest trophy.

"If the stars align," Holroyd says, "I think we can pull off something exceptional here."