America's Cup: Kiwis to use Cup champion as AC75 test boat for Barcelona 2024
by Richard Gladwell, Sail-World.com/nz 16 Feb 2023 05:14 PST
The AC75, Te Rehutai sits alongside Emirates Team New Zealand's LEQ12 on the right - February 2023 © Emirates Team New Zealand
Emirates Team New Zealand has followed a predictable path with its announcement, on social media, that the 2021 America's Cup champion "is back in the shed and will be back out foiling around the harbour with one or two new configurations in due course."
The expected move was confirmed by the team, with a photo posted on social media with the winning AC75 sitting in the team's Wynyard Point Base alongside the wingless test boat LEQ12, which has 17 days of test sailing in its logbook.
It was a serendipitous moment with the image and short comment, a day short of the fifth anniversary of the team unveiling its cyclor positions five years ago on February 17, 2017
The announcement follows a familiar path to the 2007, 2013, 2017 and 2021 America's Cup campaigns, where an effective two-boat program has been run, regardless of the intention of the America's Cup rules at the time.
In 2007, prior to the development of simulators by the AC teams, it was the usual practice to build multiple America's Cup class yachts and run what was known as a two-boat program. That involved engagement of two sailing crews and tedious months of testing one configuration against another, before doing a rinse-and-repeat cycle on the other boat to verify a speed or sailing angle gain.
In 2013, following a change of America's Cup Class, the ETNZ's first build of a full-size AC72 wingsailed catamaran, was fitted with foils - something not contemplated by the rule-makers. The move resulted in complaints to the America's Jury by Emirates Team NZ after an adverse ruling from the Measurement Committee effectively ruled against daggerboards being used as foils.
ETNZ's complaint that the Measurement Committee had exceeded its jurisdiction (and effectively created a new Class rule) was upheld. However, the Kiwis had prematurely revealed their hand, and the other three teams followed suit. But the America's Cup was changed forever.
In 2017 Emirates Team NZ found a neat way around the rules by developing a test platform using the required AC45 hulls but added an almost metre-long rudder gantry, which gave the team the foiling geometry of an AC50 which was the America's Cup Class for the 2017 Cup in Bermuda.
That move gave the Kiwi team a six-month head start with AC50s on the other teams, which were allowed to launch only one AC50 wingsailed foiling catamaran. The Kiwis gained the advantage by using full-size AC50 components on the test boat. Some of these were transferred across to the race boat, having been thoroughly "road=-tested".
It was a similar story in 2021, following yet another change in America's Cup Class, where two AC75 boats were permitted to be built. Te Aihe (now used as a trial horse by the Alinghi Red Bull Racing team) was developed, and many of the working systems were transferred across to the raceboat, Te Rehutai and the development which started on Te Aihe was transitioned to the race boat, and continues until it is no longer practical.
The practice of using a top yacht from the previous Cup as a trial horse stems back to the buildup to the 1958 America's Cup, when the Match was sailed for the first time in 12 metres. When the Brits used a couple of existing 12's to get the team rolling prior to the construction of their challenger, Sceptre. The game then moved on to the design and construction of specific development boats as well as the raceboat. That practice became prohibitively after America³ built four boats to the then new IACC rule, as well a computer modelling every challenger. The expensive practice was restricted to construction of just two new ACC boats was until 2013. Ironically when the bills are totted up at the end of a campaign, the spend on a development boat is often more than the race boat. They can be an expensive learning experience.
Under the current America's Cup rules, Emirates Team New Zealand can't sail Te Rehutai against their new AC75 raceboat, but ashore they can sail it against the simulator computer. The latest performance data from Te Rehutai can also be used as input into the AI-based system developed for the 2021 Cup, which will likely be extended for Barcelona2024.
On the water, ETNZ can sail against their LEQ12 development boat, which is a turbo-charged AC40 hull taken out of one-design class configuration.
ETNZ, who designed the AC40 hull, took the courageous option of designing it as a step-on from Te Rehutai, and gained some advantage from it being of the same design genre, to the Cup champion, rather than producing a more radical boat. The tradeoff with that approach was they also part-revealed their future design thinking to their competitors.
Those competitors also have the option to do exactly what ETNZ have done - sailing an LEQ12 based on the AC40 hull against an existing AC75 and gaining an insight into the Cup winner's design thinking.
The recon team reports that the LEQ12 is nearly as quick despite being almost half the size of an AC75. However, the primary use of Te Rehutai will be to measure its performance data against the Version 1 AC75 configuration against various performance benchmarks that ETNZ, and all teams will have developed.
Lighter and better
The Version 2 of the AC75 class rule has several changes to the Version 1 AC75 used for the 2021 America's Cup. Te Rehutai will be a full-sized test bed for some of the Version 2 rule features.
One of the changes will be the testing of the use of cyclors, continuing the work of then-rookie performance engineer Elise Beavis, who was assigned to the secret project soon after she joined the team in 2015 - straight from the University of Auckland with a Bachelor of Engineering degree with First Class Honours.
While cyclors were not illegal in the 2017 America's Cup, other teams did not move on them for various rumoured reasons. By using cyclors, Emirates Team New Zealand made a significant gain in power and speed of hydraulic pressure replacement.
That crucial tack in the 2013 America's Cup, when the AC72 almost capsized due to a lack of hydraulic pressure, probably points to much of the Kiwi thinking, taking more risk than the other teams. A comment from one team member who left the NZ team after the 2013 Cup and rejoined for the 2021 campaign, was that he was amazed as to how much reliance the Kiwis placed on simulators and performance prediction, and the reliance/confidence they had in the outcomes.
Bond on board
The Kiwis virtually confirmed their direction of travel for the 2024 Cup with the announcement at the end of January of triple Olympic Gold medalist rower Hamish Bond and three others with strong cycling, rowing and multi-sport backgrounds. They joined a team of returning cyclors/grinders - part of the winning team from the 2017 and 2021 America's Cups. Bond's last role was as the stroke of the Gold medal-winning Eight at Tokyo2020. Between Olympics, he switched to cycling, winning a Bronze medal in the 2018 Commonwealth Games road time trial.
Pedal power was not allowed in the Protocol negotiated between the Royal New Zealand Yacht Squadron (ETNZ) and the then Challenger of Record Circolo Della Vella Sicilia (Luna Rossa). However, it is now legal in the current Protocol, which was negotiated between RNZYS and the AC37 Challenger of Record, Royal Yacht Squadron (INEOS Britannia).
The bottom line is that ETNZ will enjoy the benefit of applying learning from a previous campaign. The other teams are starting with a blank piece of paper regarding the application of leg-powered technology in the America's Cup.
New York Yacht Club's American Magic does have a cycling partner in SRAM - one of the world's most innovative bicycle component manufacturers and has fitted cycling stations into their test AC75 - Patriot - the team's challenger from the 2021 America's Cup.
There were no published shots of the cycling systems used in the 2017 Cup. So far in the 2024 Cup, despite the many cockpit shots of American Magic's cockpit, there is nothing in the Reconnaissance File System (RFS) that shows Patriot's cycling system. The black carbon fibre backdrop of the cockpit interior provides a very legal disguise.
Other design avenues
Another difference in the Version 2 AC75 Class Rule, which the Kiwis will need to verify full size, is the effect of the reduction of boat weight by around 900kg.
Gains from putting the AC75 on a weight reduction program are achieved by several means, including removing the Code Zero foresail and bowsprit. (That effectively reduces the AC75's length from 75ft to 69ft).
Another is the reduction in crew numbers from 11 sailing crew to eight, who are expected to be split across two cockpits. Part of the testing will be whether those crew remain at their allocated station, as in the AC40s. Or cross to the windward hull and add to the righting moment, as they did in the 2021 America's Cup cycle.
Under AC75 Version 2, the total crew weight is set at 700kg for eight crew members, down from the 990kgs total permitted under Version 1. That, in turn, equates to a slight reduction in average crew weight from 90kgs to 87.5kgs.
The wing foils are permitted to be bigger under Version 2, and the overall depth of both the standard supplied arms and wing foils to be 200mm deeper.
The weight reduction and increase in wing size are expected to reduce the difficulty of AC75s to get foiling in minimum racing winds strengths while keeping speed-sapping drag to a minimum.
Part of the investigations with cyclors on the upgraded AC75 will be around the weight and configuration of systems used and making those as efficient as possible.
In the 2017 Cup, one primary cyclor was used, Simon van Velthooven, always at the front of the AC50 peloton and joined by two or three others. One benefit of cyclists over grinders is that a flight controller like Blair Tuke can provide leg power if required. How this will work out in the AC75 needs to be tested full size. Cycling stations are not fitted into the 39ft LEQ12.
Other areas of full-size investigation will include a new jib sheeting system now that self-tacking jibs are permitted. The British team have been testing a very elegant solution to the jib sheeting function.
Similarly with mainsheet systems - in the 2021 Cup, the Kiwis were the first to dispense with the traditional mainboom in favour of a boomless clew sheeted, hydraulic control of the double-skinned mainsail. The other teams have emulated that concept on their AC75 or LEQ12 (40ft) test boats.
An open spy system
What the Kiwis have up their modified AC75 will be watched closely by the other teams, except in this Cup cycle they have to watch through the lens of the AC37 Joint Reconnaissance team. Individual team espionage units are now not permitted to operate on the water or land, aside from casual photos taken from onshore by a mobile phone.
Using high-powered binoculars by shore-based team spies appears to be quite legal while a team is rigging and launching. Based on these observations or an analysis of the daily content in the RFS, a team spy can request specific shots from the local recon team member.
The pressure is expected to go onto the local recon team, with the Challengers expected to sign off on their final raceboat designs in a month or two.
In the days when there was little restriction on recon teams' activities, some very aggressive RIB driving was commonplace as the spies jostled to get into the best position to shoot images and report on new developments. It was not unusual to see crews following team New Zealand and on the phone back to their base in Europe or USA during a sailing session. Obviously, with current technology, it would have been easy to send live images back during the session and receive further shooting viewing instructions, speeding up the efficiency of the reconnaissance process.
It remains to be seen if other teams also opt to re-launch first or second-generation AC75s.
American Magic have decommissioned their second generation AC75 Patriot, which was partially upgraded to the suit Version 2 of the AC75 Class Rule. They have over 40 days sailing in their log book - mostly very useful speed training in flat water.
The Challenger of Record, INEOS Britannia, have donated their AC75 2021 Prada Cup finalist to the Cowes Museum.
ETNZ's modifications to Te Rehutai will be closely followed in the coming weeks.
On the basis of their past history some novel developments can be expected if ETNZ continue their overriding approach, as explained by team boss Grant Dalton after the 2017 Cup win, which is 'to throw the [design] ball out as far as we could and then see if we could get to it'.
We will keep you informed.