During Leg 4 of yesterday’s last Louis Vuitton race, as Luna Rossa crossed in front of American Magic’s bow, an audible crack was heard, and the Italians lost pressure in their rig due to a failure in the mainsheet hydraulic control.
How did it all come to this? American Magic, on a starboard gybe and hitting over 35 knots, cut across Luna Rossa’s course, holding right of way. Luna Rossa, approaching from the port side, was under intense pressure to make a critical cross in front of the US challenger and secure right of way before both teams headed for Mark 4, with two legs left to sail. At the moment of the incident, Luna Rossa was flying at 40 knots.
Although the AC75 wasn’t moving particularly fast, the rig was under considerable strain as Luna Rossa tried to gain enough speed and angle to cross in front of American Magic. It is speculated that there was 20 tonne of pressure on the on the mainsail traveller. One potential factor could have been the confused sea state caused by a mistral further out in the Mediterranean, which may have subjected the system to earlier shock loading. Still, the boat seemed stable at the time of the incident.
In the immediate aftermath of the incident, skipper Jimmy Spithill noted that the traveller appeared to be intact and hadn’t torn away from the hull. The most likely culprit seemed to be a failure in the hydraulic mainsheet system, which controls the tension on the double-skinned mainsail.
Ironically, it was Luna Rossa who, back in the 2021 America’s Cup, pioneered the removal of the two running backstays that typically help tension and support the rig. There was some debate about whether their removal, which reduced wind resistance, or pinning them against the mast, was legal. In the end, the backstays had to be carried as part of the official rigging. However, just like a few other innovations from the Italians during that campaign, this design change was adopted as standard in the Version 2 AC75 for the 2024 Cup.
Luna Rossa had more experience with this rig style than any other team, meaning they should have been well aware of the loads in this area of the boat. This suggests that the issue was likely caused by a single component failure rather than a system-wide problem. Unsurprisingly, some hydraulic cables were damaged during the incident.
Max Sirena, Luna Rossa Prada Pirelli’s skipper and team director, explained: “It wasn’t the day we expected, but that’s sport. The first race was really close—we had a great start and led for most of it. Then, the wind dropped, and we fell off the foils. The second race was neck-and-neck with plenty of lead changes. On the second downwind leg, when we were ahead, we suffered damage to the mainsail control system, which stopped us from finishing. We’ll assess the situation and get ready for tomorrow. These boats are pushed to the limit, and unfortunately, things like this happen. Our morale is still high, we’re sailing well and we’re fast. Tomorrow, we’ll be out to bring the point home.”
In recent years, all teams have experimented with various mainsheet hydraulic designs to reduce wind resistance while still providing enough force to tension the rig. These hydraulic mechanisms, typically hidden within the sail, are complex, and it seems a component failure led to the breakdown. The Italian design team will need to investigate what forces were at play and replace the faulty part with something stronger.
The race itself had been thrilling, with frequent lead changes, showcasing the best of grand-prix foiling racing and the Louis Vuitton 37th America’s Cup, until disaster struck Luna Rossa. On leg four, the traveller system suddenly failed, bringing their race to a premature end. NYYC American Magic sailed on to complete the final two legs and notch their second win of the day.
Jimmy Spithill remained confident in Luna Rossa’s ability to bounce back. “This is high-level sport, and this is exactly what you expect. You’re always going to face a few curveballs, but champion teams deal with it, and we’ve got a champion team. Our shore crew is fantastic, and I have no doubt we’ll be back. I’d bet the farm on it—we’ll be out there tomorrow.”
At the moment we believe that for Luna Rossa to fix yesterday’s mainsheet hydraulic control issue, the team will first need to thoroughly inspect the system to identify the exact cause of the failure. Whether it’s a broken hydraulic line, a malfunction in the pump, or an issue with the control unit, they’ll need to replace any damaged components. Once those parts are swapped out, the team will have to recalibrate the hydraulic controls to ensure everything functions smoothly under racing conditions. Before heading back out, they’ll run tests under load to confirm the system can handle the intense pressure of high-speed sailing.
Additionally, they’ll check for any other potential damage that might have been caused during the incident, like strain on the rigging or sails. Given the urgency of competitive sailing, the shore crew will need to work quickly and efficiently to get the boat back to full strength without leaving any issues unresolved.
