A familiar race hull arrives in a new home
Britain's GB1 America's Cup team has brought its AC75 race yacht RB4 to Naples, completing an 800-kilometre road journey over three days from Persico Marine in northern Italy. The arrival, announced by the team on 21 October 2026, moves a substantially refitted foiling yacht into the city where the next America's Cup will be contested.
The boat will be based at Bagnoli while the team finishes commissioning and prepares to resume sailing on the Bay of Naples before the end of the year. For a campaign whose equipment must be developed under tight rules and deadlines, the move from the refit facility to the operating base marks a practical transition from workshop work towards testing.
The Barcelona AC75 gets another racing life
RB4 is not a brand-new hull. It is the same 75-foot AC75 used by the British challenger at the 2024 America's Cup in Barcelona, when the team won the Challenger Selection Series and reached the match against the defender.
GB1 points out that the result gave Britain its first challenger qualification in six decades, and that the team's performance included its first race wins in an America's Cup Match in ninety years. Reusing that yacht gives the organisation a proven platform, but it also places a premium on detailed engineering changes because rival teams are working with their own established equipment.
Class rules change what is inside the boat
The rules for the 38th America's Cup require returning teams to reuse their previous AC75 hull, rather than commissioning a completely new one. That restriction shifts design effort towards the parts of a foiling race boat that can be changed, including appendages, control systems and the integration of equipment inside the available hull envelope.
One of the most visible differences will be the disappearance of the four cyclors who generated hydraulic power in the Barcelona campaign. GB1 explains that, under the new rules, a specified battery system will supply stored electrical energy, requiring a rethink of hydraulics, electronics, internal layout and the way sailors manage the yacht.
The move to battery-powered controls does not make the AC75 a conventional electric pleasure boat. Its primary propulsion remains wind through the sails and foils; electrical systems are part of the precise control infrastructure needed to change trim and respond quickly during manoeuvres.
Five sailors, a new crew configuration
The 2027 race configuration will use five sailors and mandate that at least one is female. A separate Guest Racer position is intended to let an additional person experience the AC75 environment without joining the operational team.
Those changes have consequences beyond crew numbers. Weight distribution, cockpit layout, communications and emergency procedures are all important when a yacht must foil at high speed, so the commissioning programme will need to address how people and systems work together on this revised platform.
Commissioning in Bagnoli
Following delivery, GB1 says the boat has entered final outfitting and commissioning at its Naples base. Chief executive Ian Walker has emphasised the work completed with Persico Marine and identified foils, systems and electronics as significant areas of further development.
The next major target is to get RB4 sailing in the Bay of Naples before the close of 2026. Reaching that stage will not in itself demonstrate race-winning speed: the team must still validate new systems, build reliable operating procedures and collect enough data to guide development through the approach to the 2027 competition.
Why the refit matters beyond one team
Even for leisure-yacht owners with no intention of stepping aboard a foiling racer, RB4 illustrates a distinctive engineering challenge. The same hull can be given a very different operational character when energy systems, hydraulic architecture and crew requirements change together.
The team's official announcement establishes the arrival and the intended testing timetable, but does not publish a new measured top speed or race-performance result for the refitted yacht. Those outcomes can only become clearer once RB4 leaves the yard and resumes controlled sailing trials.
Related event: Louis Vuitton 38th America's Cup, Naples 2027.
