Cup Critiqued: INEOS Britannia and Mercedes-AMG's first ever yacht design.
by Richard Gladwell Sail-World NZ 1 Nov 2022 10:45 UTC
29 October 2022
INEOS Britannia launch prototype - T6 (LEQ12)- 27October, 2022 - Mallorca © Ugo Fonolla / America's Cup
Last Thursday, INEOS Britannia - the British Challenger for the 2024 America's Cup launched their surrogate/test yacht from the team's sailing base at Mallorca, Spain.
The team will relocate 110nm to the 2024 America's Cup venue at Barcelona when their permanent base has been constructed.
At the launch, team CEO and Skipper Ben Ainslie said the surrogate boat was the result of "a lot of work between ourselves and Mercedes F1 - a collaboration with the two teams - is the start of a long journey of testing between now and when we finalise our designs for RB3, and then the combined components for RB3, our race boat for the America's Cup."
"It's an exciting day for the team. We're looking forward to getting into serious winter testing ahead." The team's sailing operations will run out of Mallorca, while the design team will remain at the Mercedes-AMG facility, with full access to the F1 team's resources in Brackley, UK.
"We wanted the opportunity to build to design and build not only the hull but obviously all of the components that go with it with this new partnership with Mercedes. I guess it's the first true boat that Mercedes could say that they've ever designed and built."
Ainslie emphasised that T6 "is a test boat. It's not designed to be the fastest 40-foot foiling monohull around. But it will give us invaluable insight into our performance tools, and validation of those tools," he added.
That's long-hand for the painstaking process of testing their tests.
The British team were the first to launch a test boat in the 2021 America's Cup cycle with a 28ft production hull modified to become a foiling monohull. It was not intended to be an easy boat to sail - with its main function being to upskill crew.
American Magic followed with the design, build and launch of "The Mule" - just under the 12 metre length restriction for a Surrogate boat. The Kiwis followed with Te Kahu, and Luna Rossa followed with a boat that was little seen.
In this America's Cup cycle, with the teams only allowed to launch one AC75 raceboat, the surrogate boats have become a lot more sophisticated, and assume a more significant place in the Cup cycle.
Even though the America's Cup class is now a monohull, the "Platform" concept - which comes from the multihull world - is a better way of thinking about the component development and testing approach.
T6 looks like it will be a handy test platform - above and below the water. Despite Ainslie's comments T6 not being "the fastest 40-foot foiling monohull." The hull shape has to be in the same ballpark as the state-of-the-art AC75s but is not supercritical - as its main function is as a testing platform.
As most Cup-watchers will know, the Brits were caught with their pants down at the start of the last America's Cup, with an AC75 which had serious foiling issues at the bottom end of the wind range. With the assistance of their friends at INEOS, the Brits' ability to turn that situation around was quite remarkable and a real pinch-me moment for Cup aficionados.
Against that run of form, the first day's results in the Prada Cup saw INEOS Britannia scoring back-to-back wins. To the surprise of everyone, and probably themselves, the Brits went on to win the Qualifiers with five wins from five races and progressed straight into the Prada Cup Finals. That outcome was a massive turnaround for a team that just over three weeks earlier was lapped in their final race of the Christmas Cup.
At the time, it was not surprising to see Ainslie's team leveraging off their F1 relationship with Mercedes-AMG Petronas, along with other resources and synergies available in the INEOS group. What was remarkable was that the situation could be turned around so quickly.
Of course, just over a year later, Mercedes-AMG had a few design problems of their own, with their F1 cars porpoising and bouncing for the first three months of the current season.
Against that backdrop, along with the recruitment of Martin Fischer, a lead designer with Luna Rossa, the unveiling of the Brit's test boat was awaited with a level of intrigue.
A couple of shining sensors protruding from the foil wing bulbs provided the first talking point.
"Those sensors give us much more accurate data feedback in terms of what's going on under the water, along with the foils and the performance of the boats. It's an incredibly well-sensored boat," he added.
T6, like Te Kahu, Emirates Team NZ's test boat of the last cycle, has distinctive multiple hard chines and angles, along with flat hull sections. It is a fair bet that the INEOS Britannia race boat - RB3, will have much softer and rounded lines.
After the Cup moved away from the 12 Metre class, the International America's Cup Class rule was developed by a group of designers working as a committee. The IACC rule was used for five America's Cup cycles covering a period of 15 years. Towards the end of the cycle, the designers all moved into the same corner of the rule producing narrow boats, with length governed by the tradeoff against sail area.
One of the surprises of the recent launchings of a fleet of surrogate/test boats is that the team designers don't seem to have started moving into the same corner of the AC75 class rule and began producing similar hull shapes.
There are maybe a couple of reasons - first, that these are just test boats, and second that the designers obviously feel there is plenty of speed left on the table.
Images 1 and 2 above shows that the aft half of the deck of T6 is like a tennis court. At its forward point is the full-width jib track, and with the full-width mainsail traveller at the after end. In between is a very straight sheerline, with little outboard shape in it - causing the maximum beam to be carried right to the transom.
The deck is flat without the centre-line cockpit trench present in the AC40's of Emirates Team New Zealand or the LEQ12 of Luna Rossa Prada Pirelli.
The crew cockpits shown in the deck images above, look a little larger than normal, otherwise, the deck layout is similar to Te Kahu. The close-ups of the cockpit give no indication as to whether cyclors will be used - and if so, whether four or six crew will be carried. As well as their relationship with Mercedes-AMG Petronas Formula One Team, INEOS Britannia also have a strong relationship with the INEOS Grenadiers professional cycling team.
The mast is deck stepped, and with this deck layout, the Brits will be unable to test the advantages of a lowered central deck or centreline trench used by Emirates Team NZ in its Cup-winning AC75, and also featured on Luna Rossa's LEQ12, launched recently in Sardinia.
That will come from the AC40, of which INEOS Britannia have acquired at least one. The AC40 does feature the centreline trench, and INEOS will be able to test the lowered rig concept on that boat, and make comparisons with T6, which is also an LEQ12 under the Protocol which governs the next America's Cup.
Drop down to Image 12, and we can see T6 has a very flat aft section underbody similar to Te Rehutai, the AC40 and Luna Rossa's LEQ12.
There is a centreline bustle, which looks like a skeg from some angles. It is disguised by interesting hull graphics, but viewed from astern, it has some volume - as do the other teams have with their LEQ12s.
Images 4 and 5 show a slab sided topside hull shape - which is typical of test boats, and indeed the AC75s. The foil arm pivot is contained within the hull without being faired into the hull in any way, which happens on the AC75.
There are no beam restrictions in the AC75 class rule, and the only restriction, which effectively controls beam, is that the distance between the Foil Cant Axis point, is set at 2050mm from the centreline, with a very small +/-2mm tolerance. Hull volume beyond the foil arm pivot point is free - but is obviously slightly heavier and may add some drag.
In Image 10 we can see the hull tapers away to almost nothing at the transom, which is a nod towards aerodynamics and drag reduction, as well as assisting with the objective of the hull being an endplate on the rig.
Images 7 and 9 show the volume of the hull bustle is quite a contrast to the view of the same appendage shown in Image 11. However, the bustle illusion is caused because the appendage is nicely tapered at both ends - with its volume in the centre.
Images 3, 4 and 5 show the Brits are initially testing the same minimum section, low lift, high-speed foil wings concept favoured by Emirates Team NZ and America's Magic in the 2021 America's Cup.
The unusual feature on the foil wings is the prominent forward protruding sensor, with a further sensor in the wing body. The Mercedes-AMG designers bring a strong body of knowledge of F1 aerodynamic knowledge - which appears to be crossed over into the America's Cup projects. It is likely that they will be picking up on where they left off with their AC75's foiling issues in Auckland, and will be looking for data from the wings on the LEQ12 to understand the issues and test solutions.
Wind tunnel testing is illegal in the America's Cup and has been for a couple of Cup cycles. But it is still legal and a key part of the F1 design process. Given that INEOS Britannia is in a technology partnership with Mercedes-AMG Petronas Formula One Team, it is not too much of a stretch to see some of their designers, who can "see" air molecules, turn their thinking to water and how they would measure denser fluid flows, and come up with some new approaches to reducing the incidence of foil cavitation.
We've not seen this style of sensor previously in the America's Cup. But it's the same approach that got Emirates Team NZ into the simulation in the build-up to the 2017 America's Cup and then into the use of artificial intelligence in the last America's Cup.
Images 8 and 9 show an interesting bow shape where the designers have married a forefoot bustle for lift-off assist, with a flared bow to provide emergency lift in a nose-dive situation. The design team have used the sheerline to nicely blend the canoe body of the hull into the deck.
Next up is the usual tow testing to check foils and flight control systems.
"We'll do quite a bit of tow testing, and more testing that we've seen the other teams do," Ainslie explained in a dockside interview with the AC37 Joint Recon team at the launch. "We want to take these aerodynamic variants out of our tow testing results."
"We'll go through that, over the next week or so, and then get the rig into the boat and get sailing and start having some fun with it."
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.