Please select your home edition
Sea Sure 2021 - Transom Fittings - LEADERBOARD

Cup Spy: Alinghi Red Bull Racing make gains but AC75 is still a work in progress

by Richard Gladwell/ 5 Oct 18:22 PDT 5 October 2022
Alinghi Red Bull Racing's AC75 attempts a foiling tack - Barcelona - October 5, 2022 © Alex Carabi / America's Cup

Alinghi Red Bull Racing has spent two long days on the water off Barcelona, as the crew work up their first generation AC75, purchased from America's Cup champions Emirates Team New Zealand.

Both days have been typified by typical Autumnal weather for Barcelona with light winds, sometimes building later in the day. We are well into the final month of the 2024 America's Cup at Barcelona. Today the wind in the afternoon was estimated at 7-8kts, building from 5kts earlier in the afternoon.

Fortunately for the Swiss team the seas have been slight with little cross swell apparent from video shot by the independent reconnaissance team.

On Tuesday October 4, team principal Ernesto Bertarelli joined the team for a day on the water to check progress, he was reported as being well pleased.

The tracking shows the team covered over 40nm during the course of the day, however some of this was spent under tow as the team changed location in search of more consistent breeze going in the direction of the airport.

It is not clear from the available content whether the AC75 was able to get foiling unassisted in these conditions, when the required takeoff speed is around 15-18kts. The normal practice, when training in these conditions is to tow the boat onto its foils and then release to continue sailing in the same way that a glider is launched behind a drone, before it starts soaring for the rest of the flight.

The purpose of towing up is to lift the hull and reduce drag from the main foil arms, but also to allow the AC75 to generate it own apparent wind and keep sailing once the tow is dropped. However it is unusual to be able to execute a foiling tack or gybe at the end of a run in such light winds, and this is what happened to the Swiss.

When used the towline appears to be very thin indeed, to be almost imperceptible, and usually only be seen against a contrasting background colour.

Two foiling gybes and three foiling tacks were attempted. None were successful, which is the expected outcome in these circumstances and stage of the AC75 campaign. It is assumed that the Swiss have kept the first generation AC75 in the same mode required in the class rule, meaning that the Version 1 boats are about 1000kg heavier than the Version 2 designs which won't be seen for 12-15 months. The heavier weight makes foiling more difficult in the light conditions, which is what is being seen with the Swiss. It is not known whether they are sailing with eight crew permitted for the 2024 America's Cup, or if there is the full complement of 11 sailing crew permitted for the 2021 America's Cup. The difference in weight will be about 300kg more for the Boat Zero foils to lift in light conditions.

Session Statistics - Barcelona October 4, 2022 - Alinghi Red Bull Racing - AC75 Version 1

  • Wind Strength (PM): 7-9 knots Wind Angle: E (PM)
  • Sea State: 3
  • Temperature: 21 degrees
  • Crane in: 0900 Dock Out: 1300
  • Dock In: 1745 Crane out: 1815
  • Total Tacks: 3 (Displacement)
  • Total Gybes: 2 (Displacement)
  • Estimate TWA: 90 degrees
  • Sails: M1- 1R with J1-3L (1 hour 50 mins).

An improvement on Wednesday

On Wednesday October 6, the Swiss team was again on the water off Barcelona in similar conditions to the previous day, however the breeze built during the four hour session, with only a modest increase in sea state, being a slight wind chop, and possibly a small swell. Like yesterday the wind strength was estimated at 4-5kts early in the afternoon building to 7kts from the East later in the day.

The recon team reported that one of the six tacks attempted today did not result in a touchdown - which in the conditions is a significant gain. Both gybes resulted in a touchdown. The final tack of the day was marred by a foil operation error by the crew. Unlike the Emirates Team New Zealand crew which made the same error on their AC40, on the same day in Auckland, the error did not result in a capsize.

Wind conditions at the end of the session should have been enough for the AC75 to get foiling, however only one video clip shows this happening - in what appears to be an easy lift off, with minimal wash appearing off the main foil arms as the AC75 accelerated to takeoff speed. In the one clip unassisted showing lift-off, the AC75 gets foiling before the bow dips back into the water, possibly catching a swell, before lifting back out again and getting up to foiling trim and speed.

In the videos ARBR's Boat Zero appears to be sailing in a normal fore and aft trim and ride height - similar to Te Aihe when sailed by Emirates Team New Zealand, and without the bow down posture that ETNZ's second, and 2021 Cup winning design Te Rehutai adopted, and seen again on the recently launched AC40. The reason for the bow-down attitude on the later designs is to improve the end-plate effect between the rig and the water surface and improve aerodynamic efficiency.

It will be interesting to see if the Alinghi RBR design team adopt the same cutaway after section, used by principal designer Marcelino Botin in American Magic's second AC75, Patriot, to help get the boat clear of the water during lift-off. The draggy aft section is a noticeable feature of all video seen to date in marginal foiling conditions.

It is not known whether the Swiss are sailing under an automated flight control system, or are flying the AC75 manually - something that is cannot be seen on the video, and about which the team has not been asked to date.

The Swiss team are expected to resume sailing on Monday.

Session Statistics - Barcelona October 5, 2022 - Alinghi Red Bull Racing - AC75 Version 1

  • Wind Strength 5 knots (AM) 7-8 knots (PM)
  • Wind Angle: E (PM) Sea State: 3
  • Temperature: 21 degrees & sunny
  • Crane in: 1100 Dock Out: 1310
  • Dock In: 1750 Crane out: 1825
  • Total Tacks: 6 (Displacement) 1 (Foiling)
  • Total Gybes: 2 (Displacement)
  • Estimated Speed of take-off: 17 knots
  • Estimated TWA: 90 degrees
  • Sails: M1- 1R with J1-1R (3 hours)

Related Articles

Cup Spy Dec 2: Luna Rossa swims .. Am Magic flies
Luna Rossa capsized in a rapidly building breeze. American Magic foiled solidly for 75nm. Luna Rossa Prada Pirelli, the Italian America's Cup challenger capsized in 21-22kts winds after being caught in a rapidly building breeze and sea state. In Pensacola American Magic put another 75nm in their logbook foiling for 2hrs 43min. Posted on 3 Dec
Cup Spy Dec 1: American Magic caught short
Lesson for all teams as to how crucial the correct sail choice will be in 2024 American Magic spent over five hours on the water, covering 55nm, in lighter winds than expected. Unfortunately the team made the wrong mainsail choice, in the expectation of stronger winds, and had to do tow-starts 75% of the time. Posted on 2 Dec
Cup Spy Nov 30: Fun but Frightening
Italian Flight controller: "The boat is pretty scary in that condition." Plus a look at that Pole. The Italian challenger say they had a "productive practice day" on Wednesday, sailing in their strongest wind yet in their LEQ12 prototype. We look at the British team's battle over the legality of their Instrumentation Pole. Posted on 2 Dec
America's Cup: Match dates released
AC37 Event Limited (ACE) have confirmed both the intended race area and the race dates for the Ameri AC37 Event Limited (ACE) have confirmed both the intended race area and the race dates for the America's Cup Match 2024. The 37th Match will start on October 12, 2024 and racing is scheduled to October 27, 2024. Posted on 30 Nov
Cup Spy Nov 29: American Magic flies high
Motorsport mogul Roger Penske drops in on American Magic. USA and Italy clock up big miles. Motorsport mogul Roger Penske drops in on American Magic, and brings a fresh breeze to Pensacola Bay. USA and Italy clock up big miles on the water in Pensacola and Cagliari. Who will be the first to a 100nm day? Posted on 30 Nov
Cup Spy Nov 27: Luna Rossa sails, Brits tweak more
Luna Rossa went sailing unexpectedly on Sunday, as the Brits continue to twing and twang Luna Rossa Prada Pirelli's LEQ12 went sailing unexpectedly on Sunday afternoon, after being under repair since dropping their mast while rigging on November 6, and damaging the mast head. INEOS Britannia continued their mast setup in Mallorca. Posted on 28 Nov
America's Cup: Rigging the Silver Arrow
The INEOS Britannia shore team and technicians had a busy day dockside in Palma The INEOS Britannia shore team and technicians had a busy day dockside Friday in Palma with the crucial first-stepping of the ‘Silver Arrow' T6 LEQ12 carbon mast and rigging. Posted on 26 Nov
America's Cup: AC40 construction changes announced
Construction changes announced for existing and future AC40 builds following AC40 nosedive Emirates Team NZ have announced the design and construction changes to be incorporated into existing and future AC40 builds. The changes have been developed as a result of damage that occurred after the violent nosedive of the team's LEQ12, on Tuesday. Posted on 25 Nov
Cup Spy Nov 24: Brits foil testing again
Six days after doing their first towing test in Mallorca, INEOS Britannia did a second session Six days after doing their first towing test in Mallorca, the British America's Cup Challenger, INEOS Britannia, did a second towing exercise - with the delay between runs put down to inclement weather. Posted on 24 Nov
Cup Spy Nov 23: American Magic trials new main
American Magic trials new main, does plenty of dry tacks/gybes and gives cyclors a workout American Magic made further gains on the other four teams contesting the 37th America's Cup, with another strong day on Pensacola Bay, sailing in light winds with a newly recut, and larger mainsail. Posted on 24 Nov
Sea Sure 2021 - FLO - FOOTERJ Composites 2022 - J99 FOOTERCoast Guard Foundation FOOTER 2