La Roche-Posay Racing Team's AC75, B1, capsized during a downwind run at Lorient at around 16:50, after a systems failure sent the boat over onto its port side to approximately 90 degrees at around 35 knots, the masthead resting on the water. The crew were unharmed, and the sailing and shore teams worked through the evening to recover the boat.

Co-CEO Bruno Dubois confirmed all crew were safe and accounted for, playing down the incident. "Everybody is okay. I would say the one who didn't capsize didn't sail a lot, honestly. This happens quite a lot. We have no keel on the boat. There's a few system issues on the boat, and the boat went slowly on the side, and everybody is fine, and it took some time to get the boat back together. But, yeah, it's fine."

The on-water recon team observed that little appeared to move on B1 through the capsize, consistent with a loss of onboard systems. Several attempts were needed to right the boat, after which she sat low on her waterline, bow down, with water aboard.

Smoke then came from several deck hatches and pods. No flames were seen from the water, though the smoke, a burnt smell and the attendance of SNSM crews with firefighting equipment were consistent with a fire on board. The team and SNSM worked to make the boat safe and pump it out before B1 was side-towed towards harbour, the water taken off found to be contaminated once ashore.

The SNSM (Société Nationale de Sauvetage en Mer) were quickly on scene, assisting the shore team and managing the situation with firefighting apparatus. Dubois remarked on the composure shown by everyone involved. "I think everybody stayed quiet, and it has happened quite a lot for most of them, so it's all fine. I would say that the AC40 capsizes easier than this one, so I hope we're not going to do that too many times. But the 'Road to Naples' is quite long, so it's part of the process, and I think we've done a good job with the team to get everything back on and put the boat back right and get the sails down and bring back to the dock. The boat's in the shed."

Dubois had been scheduled as the sixth crew member for the session. Having identified the system issue, he swapped out and remained on the chase boat, allowing boat captain Antoine Rucard to take his place aboard. "It was lucky he was there in my place. He's way more qualified than me to take care of that!"
Earlier in the day B1 had shown genuine progress. She launched at 11:10, docked out at 13:01 under tow, and reached the sailing area off the north-western end of Île de Groix. A technical issue then held the boat on the water for over two hours before sailing could begin. The first run started at 15:34, with the chase boat towing B1 onto the foils before releasing. A second run followed at around 16:11, on which B1 came up onto the foils without a bow tow for the first time in the observed campaign. The capsize came at 16:50 on the third run, during a fast downwind leg after the boat had been working upwind on port.
B1 docked back in at around 20:30, was lifted out at 22:15, and returned to the shed at 23:14, the sailing and shore teams working together throughout. Conditions were sunny with light air building from the WNW to around 12 to 14 knots by the final run, a slight sea state, and the tide near slack around low water.
Dubois summed up the team's attitude plainly. "We have some water inside, a little bit. So we'll dry the boat, take the boat out of the water, do a general check and go back."
The technical team is working to identify the cause of the systems failure and complete repairs ahead of the Louis Vuitton 38th America's Cup in Naples in 2027.