RB4 rolls into Naples as GB1’s refitted AC75 begins final fit-out

The boat that took Britain to the 2024 Match has arrived at Bagnoli reconfigured for the new rules – no cyclors, replaced by battery-powered systems – and ready for final fit-out. GB1 aims to be sailing before the end of the year, a few weeks behind the French.

GB1's AC75 is back at an America's Cup venue. RB4, the boat that carried Ben Ainslie's team through the Challenger Selection Series and into the 2024 Match in Barcelona, rolled into the British base at Bagnoli on Tuesday 20 October at the end of an 800km, three-day road trip from Persico Marine in northern Italy, where it has been through an extensive refit.

The covered hull made the last leg through Naples at night on a specialist transporter before being backed into the shed under the team's “Challenger of Record” signage. Final fit-out and commissioning now start at Bagnoli, with first outings on the Gulf of Naples expected in November and the aim of having the boat properly sailing before the end of the year.

The hull is the same one Britain raced in Barcelona – previously known as ‘Britannia’ – because it has to be. The technical regulations for 2027 give each challenger one legacy hull and no new one, so the development money goes elsewhere. The four cyclors who powered the hydraulics in 2024 have gone, replaced by stored electrical energy from a specified battery system, which has meant reworking the internal layout, hydraulics, electronics and controls.

“The rules for this Cup mean we are reusing the same hull, but there is a huge amount of development taking place across the boat, particularly around the foils, systems and electronics,” says team CEO Ian Walker.

Each team can build three new wings, which must share an identical initial design, and five new flaps from no more than two initial designs, alongside their legacy parts.

Don't expect the recon spotters to see much of that. The cockpits will look different without the cyclors, but the visible changes are subtle until the race foils go on, and most of the work is inside the boat's control systems, well out of reach of any long lens.

GB1 shifted resources across to the AC75 after the Cagliari preliminary regatta, at the cost of AC40 training time before September's event in Naples, where they finished eighth of nine. The race boat came first, and the team went into PR2 having logged far fewer hours than the crews they lined up against.

The bigger picture is that the GB1 package will come together late in this cycle – an unusual position, and one the team is well aware of. With few days left between now and the first race, every one of them counts.

Until now GB1's designers have been in Portsmouth and the sailing team training out of Cagliari, and Bagnoli puts them under one roof for the first time.

The French are already well ahead of them on the water. La Roche-Posay Racing Team relaunched their modified AC75 in Lorient in July, then launched it in Naples at the start of this week, on Monday 16 October. Emirates Team New Zealand were first back on the water this cycle, sailing Taihoro on Auckland’s Waitematā Harbour on 13 March, and Luna Rossa followed off Cagliari on 10 June. Team Australia, by contrast, have only just finished rebuilding Te Rehutai and are not targeting arrival in Naples until February.

There is still the question of who owns the boat. In March Ineos said RB4 belonged to it and that it was taking legal steps to get it back, while GB1 maintained the assets belong to Athena Racing and have always been in its possession. Ineos Racing Ltd is suing Athena Racing Ltd at the High Court in London. Ainslie, for his part, maintains that Athena Racing owns the yacht and that he has no concerns about racing it in Naples.

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The Louis Vuitton Cup opens with fleet racing on 22–23 May 2027, with the match-racing round robins from 26 May and the America's Cup Match starting on 10 July. That leaves GB1 roughly six months between a November first sail and the start of racing to develop a boat whose package, by the team's own account, comes together late.