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Cup Spy Sept 25: Luna Rossa resume testing, Swiss expected to shift to AC75 soon.

by Richard Gladwell/Sail-World NZ 26 Sep 2023 01:05 PDT 26 September 2023
Alinghi Red Bull Racing - AC40 - Day 8 - Barcelona - September 25, 2023 © Paul Todd/America's Cup

Two teams sailed on Monday - Alinghi Red Bull Racing off Barcelona, continuing their development program from last week. Luna Rossa resumed sailing off Cagliari, in their LEQ12 test boat.

Gautier Sergent - lead for aero and sails on Alinghi Red Bull Racing, and Hamish Wilcox, coach and meteorologist for Luna Rossa Prada Pirelli, comment on the two sessions.

What happened in the Cup - September 25, 2023:

  • Alinghi Red Bull Racing - sailed off Barcelona in marginal foiling winds, conducting sail testing and 'model validation' - verifying their computer based performance models against the data recorded on the water.
  • Luna Rossa Prada Pirelli - sailed off Cagliari in a 8-12kts breeze in their LEQ12.
  • INEOS Britannia - no report from their Recon team.
  • Emirates Team New Zealand - no report from their Recon team.
  • American Magic - no report from their Recon team.
  • Orient Express Racing Team - no report from their Recon team.


After Monday's sessions had concluded, the Michele Melis, the AC37 Joint Recon Panel member assigned to Luna Rossa Prada Pirelli, spoke with Hamish Wilcox, a top Olympic coach and weather guru working with the Italian team.

He described today's session as a shakeout and working through the "gremlins that creep in after almost a month of not sailing. We found a few," he added. Obviously, we have to shake some rust off the sailors because it's been a while since they sailed. This boat is very tricky to sail and we needed to shake some rust out of the boat as well, and find some problems to fix."

"Luna Rossa's LEQ12 is a tricky boat to sail. So I think it's going to be really good training for us are moving to the AC75. I think the transition out of that boat to the '75 will be a smoother one than it would otherwise be."

Wilcox's impression of the AC40 was that with an auto-pilot to handle flight control the AC40 provided a "level-playing field". The AC40 did not have the quirkiness of the AC75's which are performance focused, and which the sailors have to learn to sail to the boat's potential, rather than the more forgiving nature of the AC40 - which was also designed for Youth and Womens sailors operating at a lower skill level than the America's Cup crews.

The sailors in Cagliari sat in the middle of a thermal breeze battling with an incoming seabreeze, but by picking their locations, found 8-12kts of workable wind pressure. Off Barcelona the breeze was hovering around 6kts - below the minimum for racing, and in which the AC40s usually get a tow-up onto their foils.

Gautier Sergent who is the sail and aero lead with Alinghi Red Bull Racing was philosophical about what can be achieved in today's conditions. "The breeze was very unsteady, was really puffy and very marginal as well. She's sailing in a breeze of six to seven knots, and then all of a sudden, you have one less knot, and you're in a touchdown - it's not enough to keep the bottom clear of the water," he told AC37 Joint Recon Panel member Elia Miquel.

The Swiss team used the day to evaluate sails, and two jibs in particular.

"As you can see, we have a lot of telltales on the sail, so for us, that's a first visual check," he said explaining the sail evaluation process. "And then obviously, we put all the data coming in from the boat that we are analyzing and compare it to our models."

That is a standard approach - tuning the computer model to reflect the expected and actual boat performance, enabling various design ideas to be tested ashore, with the more promising versions being taken further on a simulator and into a test part. Of course the underlying issue is the scalability from a 40ft test boat to the larger and heavier AC75, with a taller rig.

On Monday the team tested a couple of J1 and J2 jibs. "Essentially, there's just a difference in size and structure, just because it's [the J2] is made for a [stronger] breeze," Sergent explained. On AC75s in the last Cup, the key with the jibs seems to be to carry the smallest possible for the wind strength, as once foiling the apparent wind increases significantly the sails have to be effective through a wide wind range, without adding drag, and with sufficient strength to handle expected sailing loads, and shockloads. So far we have seen three occasions when the clew has been torn out of jib during a violent nosedive due to the shockloading being greater than the sail engineers anticipated.

"A big part of our job is to validate the model," Sergent said. "So when we go in the water, we call that 'model validation', which is making sure that what we see on the water is what we see in the models, and if we gain confidence on the 40s - that means whatever we do to the AC75 will also be applicable," he added.

It would seem that the Swiss AC40 test program is drawing to a close, for the time being. Responding to a question on their AC75 program Sergent replied "I don't have the exact plan but yes, our next move will be sailing in the AC75. I don't know the exact day."

Alinghi Red Bull Racing have to ship one AC40 to Jeddah to compete in the next Preliminary Event in late November, and may ship a second to enable two boat testing to be undertaken in steadier winds and flatter seas expected at the next venue.

AC37 Joint Recon Team Reports:

Alinghi Red Bull Racing AC40-4/LEQ12 - Day 8 - September 25, 2023 - Barcelona

Alinghi Red Bull Racing (ARBR) went for another sailing session with their focus on aero test in marginal wind conditions.

ARBR rolled out their AC40-7 at 11:30hrs equipped with one design foils. The yacht was subsequently craned in and placed alongside the chase boat. After pre-sailing checks, the team proceeded to dock out at 14:05hrs with Arnaud, Maxime, Yves and Bryan on board. They hoisted the main and the J1 inside the port, where they commenced a tow which has taken them two nautical miles away from the coast.

Wind conditions were marginal during all the session. Light and unsteady 6 kts breeze from 110º accompanied by a 0.1m flat sea state with a 3sec period.

At 14:45hrs the AC40 started foiling upwind in a straight line on their port tack after one assisted take-off. They did one tack and after 15 minutes they stopped because of not enough power on their sails. At 15:06hrs they did another assisted take-off which lasted 10 minutes and ended up in a touch down gybe. Followed by another tow, this time sailing downwind-upwind 6NM away, were they reached the 30kts and ended up in the same way.

With an unsteady 6 knots breeze, the sailors were trying several times to go from reaching to 30 degrees upwind, without losing their flight, which was apparently not possible, as they were touching-down instantly. By the time they lowered the J1 and hoisted the J2-2-LE the Recon boat had to leave the session to go to the fuel station. Once back, they were towing the boat back inside the harbour, without any crew configuration change. They lowered the sails inside the port and docked in by 17:40h.

The team spent three hours on the water, covering 40NM, of which 60 minutes were spent sailing. Six maneuvers were performed, four of them were fully foiling.

Crew: Arnaud Psarofaghis, Maxime Bacheline, Bryan Mettraux, Yves Detrey

Session Statistics: Alinghi Red Bull Racing AC40/LEQ12 - Day 8 - September 25, 2023 - Barcelona

  • Weather: clearing skies 22°C
  • Wind Strength 6kts
  • Wind Direction:110°
  • Sea State: Flat from 160°
  • Crane In: 1130hrs Dock Out: 1405hrs
  • Dock In: 1740hrs Crane out: 1820hrs
  • Total Tacks: 3 - Fully foiling: 2; Touch & Go: 0; Touch Down: 1
  • Total Gybes: 3 - Fully foiling: 2; Touch & Go: 0; Touch Down: 1

Luna Rossa Prada Pirelli - LEQ12 - Day 87 - September 25, 2023 - Barcelona

After almost four weeks of keeping the LEQ12 in the shed, the Italian team LRPP rolled out their prototype at 11:15, craning it in twenty minutes later.

The appendage configuration seemed to have remained unchanged compared to D86 with the removal of the inboard tip winglet on the portside anhedral wing and flat Wing-03 on starboard. During routine checks the team seemed to be spending most time on comms check, rudder rake checks from all four crew pods and, even more intensively, testing board rises/drops, perhaps running into some issues on the FCS.

At 13:15 the offshore Maestrale breeze was still quite present in the bay, approx.8-10 kts from 330°TWA (True Wind Angle). The team towed up their LEQ12 after having locked in newer mainsail M1-2 pairing it with their biggest J1-1 jib.

The LEQ12 was boarded by four crew only and towed up on starboard tack by Chase2. The breeze had turned very light within 4-6 kts and, unable to keep the yacht foiling, this procedure was repeated several times before a tow run of some minutes at a speed of 25kts was recorded.

Once back hullborne shortly after having released the tow line, the team took a quick break before setting course towards closer inshore with increased offshore breeze approx 10-12kts. Just outside the harbour the LEQ12 found some steady breeze and was able to sail for two short stints even completing some foil-to-foil maneuvers end-plating the hull on the flat waters.

After trimming up, the LEQ12 suddenly decelerated and lowered the sails, perhaps due to a speculative issue on the hydraulic systems. The day was called after a total of 7 tacks, 3 gybes, and approx. 14 total minutes foiling time [Michele Melis AC Recon].

Crew: Marco Gradoni, Jimmy Spithill, Vittorio Bissaro, Andrea Tesei

Session Statistics: Luna Rossa Prada Pirelli - LEQ12 - Day 87 - September 25, 2023 - Barcelona

  • Weather: clearing skies 28°C
  • Wind Strength 8-12kts
  • Wind Direction:315° - 325°
  • Sea State: Flat
  • Crane In: 1135hrs Dock Out: 1310hrs
  • Dock In: 1450hrs Crane out: 1630hrs
  • Total Tacks: 7 - Fully foiling: 2; Touch & Go: 2; Touch Down: 3
  • Total Gybes: 3 - Fully foiling: 2; Touch & Go: 1; Touch Down: 0

Weather conditions at Barcelona September 25, 2023:

According to the Predictwind readings taken at the entrance to Olimpic Port, Barcelona enjoyed a funky breeze of between 4.5 and 6kts average, gusting to 8kts between 1500 and 1530hrs. The wind softened to 3kts around 1800hrs - about the time Alinghi Red Bull Racing stopped sailing for the day.

While variable in strength the breeze was mostly in the East, swinging briefly to the South around 1600hrsthe breeze peaked at an average of 13kts gusting 15kts or so - around 1500hrs. The on board recordings state the breeze was 6kts 110°.

  • Sea state: Flat 0.1mtr from 160°
  • Conditions: 22° Sunny

Additional Images:

This commentary was written and compiled from video, still images and statistical content extracted from the AC37 Joint Recon program and other material available to Sail-World NZ including photo files, and other on the water coverage from the 2010, 2013, 2017 and 2021 America's Cups. Its format is intended to give Sail-World readers a snapshot of all teams' progress on a given day or period.

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