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Cup Spy August 25: AC75s line up in Barcelona

by Richard Gladwell/Sail-World NZ 25 Aug 2023 17:36 PDT 25 August 2023
Emirates Team NZ and Alinghi Red Bull Racing - Day 37 - Barcelona - August 25, 2023 © Job Vermeulen / America's Cup

[Updated Edition] Today was a rinse and repeat of Thursday at Barcelona. The notable feature of the day was seeing two AC75s on the America's Cup course at the same time.

What happened in the Cup - August 25 2023:

  • Emirates Team New Zealand sailed their AC75 in light winds - similar conditions to yesterday. The stand-out statistic from the day is off the Kiwis' takeoff - getting the boat up to 19.5kts in 4.5kts of windstrength (at sea level) - which if accurate is 2kts below the 6.5kts minimum for a race start, and even more remarkable considering the Kiwis are using the same minimum wing foils they used in the 2021 America's Cup.
  • Alinghi Red Bull Racing sailed their AC75.
  • American Magic sailed two AC40s continuing their testing from Thursday.
  • Luna Rossa Prada Pirelli did not sail out of Sardinia
  • Orient Express Racing Team - no report of the French team sailing, however they were spotted in some other images shot by the AC37 Joint Recon teams, and included in this report.
  • INEOS Britannia - no report of the British team sailing.

Commentary: Kiwi cant

Much comment has been made in the various AC37 Joint Recon team reports about the "cant angle" of Emirates Team New Zealand and other AC teams.

In the image above, it is easy to gauge the degree of cant - or heel to windward - of Te Rehutai by comparing the angle of the mast with the buildings in the background, which are dead vertical. As the boat is almost equidistant between the two buildings, it is even easier to visualise the angle of cant.

Another way of checking the angle of the cant is to look at the two "hulls" or crew cockpit islands against the horizontal sea wall in the background. The cant angle is significant but may appear less significant than without the vertical and horizontal guides of the buildings or seawall.

Judging by the number of stern view shots of Emirates Team New Zealand in the Recon File System, there is a keen interest in how the Kiwis are sheeting their sails.

The shots (taken just before Te Rehutai sailed into the position between the two buildings) show that the sails are very twisted and that the jib appears to be sheeted further outboard than the top shot would indicate.

There are several reasons for carrying this degree of twist, one of which is wind shear.

However, if the Recon report today of ETNZ being able to take off in 4.5kts of breeze is accurate, then clearly, the Kiwis have made some gains with the setup and trim of their rig since the 2021 America's Cup. Then (as for the 2024 AC), the minimum windspeed before a race start was 6.5kts, and while the AC75s could get foiling in that windstrength, it was not easy.

However, this is all part of the America's Cup guessing game, to which Peter Blake used to have the standard media response on technical questions, "That is ours to know, and yours to find out".

Also, a factor is that in training the AC75s, there are no tactical or racing considerations, and the "runway" length can be much longer, allowing the apparent windspeed to be built and takeoff achieved in maybe a lower windspeed than would otherwise be the case. Plus, the AC75 only needs to pick up a stray puff of wind above the 4.5kt measurement, and the takeoff equation changes quickly.

Two words that we have not recently heard mentioned in the ETNZ context (or other teams) are "Artificial Intelligence".

The Kiwis revealed they used AI in the last campaign. Once they understood how it could be used, they developed some confidence in AI as an extension of their lateral thinking.

They had been forced into adopting the lateral thinking approach in 2015 when the team had little money and was close to closing its doors. They had to think smart rather than indulge in building multiple test boats, as did some other teams. That was when the simulator and performance prediction tool were developed, and the Kiwis built confidence in them - they had little option to do otherwise.

Burns Fallow, a key sail designer for North Sails who worked closely with the Kiwi team for their campaigns up to 2017, commented, in a Sail-World interview, when he rejoined the team in 2018 for the 2021 Cup that he was surprised at how much weight, or confidence the Kiwis had in their simulation and performance systems as a basis for design decision making. Others commented on always trying to improve some design feature that was accepted as being fast.

Just before the 2021 America's Cup, the Kiwis and one of their partners, McKinsey and Company, revealed they had been using AI and had got some tangible benefit from it.

The other teams are assumed to have gone down the same path in the current Cup cycle. Some said they were forming partnerships. But currently, AI use has yet to be mentioned - well, from what we've seen to date.

With the Kiwis sailing their AC75 extensively in Auckland and Barcelona - having been upgraded to Version 2 of the AC75 class rule, it will probably be a story for after this Cup as to how far they have been influenced by the use of AI and its suggestions for design and performance tradeoffs, and also as they claimed in March 2021, on improvements in crew sailing technique.

The way they are canting the AC75 is one example of AI use, and trading off the negative of dragging the windward wingfoil tip against the performance gains - and being able to balance the cant to perfection. The windward cant angle has several benefits including maximisation of lateral resistance which translates into reduced leeway.

That equation also has to consider wind strength and calculate the optimum heading. In minimum windstrength, the calculation also has to determine whether it is worth investing in sailing at right angles to get the AC75 foiling and whether the apparent wind generated can be carried when the crew turn down to head for the bottom mark.

If not, their failed attempts to generate apparent wind adds to the distance the team has to sail, making winning the race much easier for their competitor.

Of course, the performance data verified and gathered by Te Rehutai from any accepted AI suggestions can be incorporated into a test script for the 2024 AC75 raceboat - which can be checked in Auckland and then in Barcelona.

AC37 Joint Recon Team Reports:

Session Statistics: Emirates Team NZ - AC75/B2 - Day 37 - August 25, 2023 - Barcelona

From the AC37 Joint Recon Team:

ETNZ rolled out their B2 AC75 from the shed at 09.33hrs. The boat was craned to the water at 10:08hrs and the team docked out at 11.05hrs, as planned. The M1 [mainsail] and the J2 [jib] were hoisted inside the port at 11:12hrs and 11:16hrs, respectively.

The intention was to train in light wind conditions before the development of the sea breeze, at least for a part of the session. To begin with, the team sailed against their targets for approximately 45 minutes, mostly on a straight line, both upwind and downwind. Similarly to yesterday but different to last week, on the upwinds ETNZ sailed slightly more heeled to windward, with the leeward foil wing closer to the surface and the wing tip coming out of the water an 80% of the time or more.

On the windward side, the windward foil remained on the limit of touching the water surface, event hitting it at times. However, when comparing to yesterday, there was much less water spray and turbulence coming out from the rudder, possibly related to a less aggressive rudder rake.

At 11:55hrs there was a short stop to execute some minor adjustments on the clew of the J2. Immediately after, the training continued with the focus on maneuvers.

Many tacks and gybes were carried out. On the gybes and trying to take advantage of the flat-water conditions, ETNZ tested to bear away and change their course slower than usual on the first part of the gybe, when going from VMG downwind course until they got to dead downwind course. As a result, downwind direction distance was noticeably gained, but not sure if it is enough to pay-off in terms of downwind VMG (Velocity Made Good) while gybing.

At 13:35hrs there was a second break, in which the J2 was dropped and replaced by the J3 due to the increase of the wind intensity. Also, a cyclors rotation took place.

After performing some extra tacks and gybes with the J3, the wind dropped again for a short period of time, and ETNZ decided to change back again into their J2 at 14:30.

Before closing the day, three complete starting sequences, starting in between their two chase boats and rounding a virtual top mark, followed by a short two lap upwind-downwind course were executed. On each of the upwind legs they complemented with three to four tacks, and with two to three gybes on the downwinds.

Te Rehutai was sailed back to the entrance of the port, where sails were lowered at 15:20hrs, the boat was back in the dock at 15:35hrs, craned out at 16:10hrs and back in the shed at 16:40hrs.

The team plans to take the weekend off from sailing, and to continue their activities on Monday next week.

Sebastian Peri Brusa – Recon on ETNZ

Session Statistics: Emirates Team NZ - AC75/B2 - Day 36 - August 25, 2023 - Barcelona

  • Weather: 32°C Sunny
  • Wind Strength: 4.3-9.2kts
  • Wind Direction: 165° - 295°degrees
  • Sea State: 0.28metres, flat
  • Crane In: 1008hrs Dock Out: 1105hrs
  • Dock In: 1535hrs Crane out: 1610hrs
  • Total Tacks: 39 - Fully foiling: 38; Touch & Go: 1; Touch Down: 0
  • Total Gybes: 37 - Fully foiling: 33; Touch & Go: 2; Touch Down: 2
  • Takeoff Speed: 19.5kts Windspeed: 4.5kts

Crew: Nathan Outteridge, Peter Burling, Andy Maloney, Blair Tuke

Alinghi Red Bull Racing - AC75 - Day 82 - August 25, 2023 - Barcelona

Alinghi Red Bull Racing's AC75 was rolled out at 09:15hrs, with mast stepping and craning completed by 09:40hrs. The shore crew measured the distance from the bottom of the bowsprit to the water surface at 980mm. Further work was carried out below deck, with data analysts, IT, electronics and hydraulics all working on board before pre-sailing systems checks.

The team docked out at 12:00hrs and hoisted the M2-2R mainsail and J2-2L jib within the port. By 12:40hrs, sailing began just outside the port entrance. The 'Garbi' South Thermal Wind ranged between 7-12 knots, gradually increasing throughout the day, with a few lulls every now and then. The sea state was consistent, with waves from the south measuring 0.4-0.6m and a 3s period.

During the initial stints, the team seemed to focus on system tests and adjustments. The team started with a short reach on starboard, underwent system adjustments, and undertook several upwind and downwind runs in the following stints. Despite short pauses between these sessions, personnel from the hydraulics and electronics departments were identified on board, suggesting work on synchronizing controls and refining close-loop systems.

Pre-start practices and tow-starts featured in the subsequent stints. Cyclors Arthur Cevey and Florian Trüb were swapped in for Théry Schir and Barnabé Delarze at 15:00 for the final hour and a half of sailing.

In the latter two stints, the team completed two-lap runs in of the 2NM course set at 190 degrees. With a minor wind increase, the J2 jib was exchanged for the J3 ahead of the final stint.

An impressive 'Jk' manoeuvre around the starboard leeward gate was performed after the first downwind, and after finishing the second lap, the team sailed a final upwind return to base.

The team concluded the day with sails lowered at 16:35, arriving back at base 20 minutes later.

Data from the recon boat showed 58 Nautical Miles covered while following ARBR over five hours on the water, with 160 minutes dedicated to sailing. The AC75 completed 81 tacks and gybes, marking its highest single-day count. Of these, 80% were fully foiling, with gybes 15% more consistent, amounting to an average of 30 moves per hour.

Session Statistics: Alinghi Red Bull Racing - AC75 - Day 82 - August 25, 2023 - Barcelona

  • Weather: Sunny 32°C
  • Wind Strength 6kts-12kts (from AC37 Recon boat)
  • Wind Direction: 190 degrees-195 degrees
  • Sea State: 0.4mtr - 0.6mtr
  • Dockout: 1200hrs Dock In: 1655hrs
  • Total Tacks: 43 - Fully foiling: 31; Touch & Go:7; Touch Down: 5
  • Total Gybes: 38 - Fully foiling: 34; Touch & Go:1; Touch Down: 3

American Magic - LEQ12 x 2 - Day 58 - August 25, 2023 - Barcelona

American Magic team rolled their AC40's from the shed at 10:45hrs with a new version of their port wing foil AM-LEQ-FW3 #3 v.D as they announced in today's Component Declaration.

They proceeded with the mast stepping procedure and by 12:00hrs both boats where in the water. The team docked out at 13:00hrs with the #Main 3 and outside the harbour they hoisted #J2.

Today's session was planned to continue testing on their foils and aero with higher and different wind conditions but it ended being similar as yesterday's conditions.

At 13:32hrs they did six warm up gybes for 4minutes and then Magic continued sailing alone.

By 13:53hrs with 9kts from 180° they both sailed upwind-downwind for 1hrs 05mins doing in total 10 tacks and 18 gybes, standing on their foils on all of them except for one touch-down gybe. They seemed very comfortable and completely under control in these wind and sea state conditions.

At 15:12hrs they changed batteries and America took advantage of checking on their port foil and applying some product. After that, they ended their training lined up with 24 tacks in a 38minutes long upwind.

At 16:52hrs they went sailing back to the harbour and sails lowered once inside the port.

The team plans to continue their sailing sessions Tuesday next week.

[Elia Miquel - Recon Unit NYYC AM]

Session Statistics: American Magic - LEQ12 x 2 - Day 58 - August 25, 2023 - Barcelona

  • Weather: Sunny 28°C
  • Wind Strength: 7.8 - 9kts
  • Wind Direction: 185° - 200°
  • Sea State: 0.26mtr Flat
  • Crane In: 1045hrs Dock Out: 1300hrs
  • Dock In: 1700hrs Crane out: 1820hrs
  • Total Tacks: 41 - Fully foiling: 39; Touch & Go: 2; Touch Down: 0
  • Total Gybes: 20 - Fully foiling: 19; Touch & Go: 0; Touch Down: 1

Crew: America: Tom Slingsby, Lucas Calabrese, Riley Gibbs, Andrew Campbell; Magic: Paul Goodison, Bora Gulari, Michael Menninger, Severin Gramm

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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