Cup Spy - May 5: Spectacular AC75 nosedive caught on video - more to come in 2024?
by Richard Gladwell/Sail-World NZ 8 May 2023 12:09 BST
7 May 2023
Alinghi Red Bull Racing - AC75 - Day 60 - May 5, 2023 - Barcelona © Alex Carabi / America's Cup
Firstly an apology to Cup Spy followers for an absence of a week, after I suffered appendicitis and was operated on late Monday night.
The Kiwi America's Cup program was suspended on April 28, for a week, while several members of the sailing team competed in the Season 3 Grand Final for Season 3 in San Francisco.
We understand that the plan is for the AC75 sailing to open up again for another week, before the AC75 is broken down and shipped to Barcelona, along with an AC40, ready to start sailing in July. ETNZ along with the other America's Cup teams, are permitted under the Protocol to only sail in Barcelona in the Period July 1, 2023 to October 31, 2023.
That final sailing week could be impacted by strong winds forecast for Auckland until the weekend, which will push the team up against shipping deadlines.
We will catch up with the Cup Spy coverage from the past week, with a priority on teams that are sailing AC75s, then LEQ12s, and then AC-40ODs.
From a quick scan of the Recon File System, used as a repository by the Joint AC37 Recon Team, the most interesting item, of the week was the nosedive of Alinghi Red Bull Racing, while sailing their AC75 on last Friday (May 5).
Will the 2024 America's Cup be dominated by the unpredictable Barcelona seastate, or is it is merely a bogeyman that has got the neurons churning in the refined atmosphere of the AC design departments?
Emirates Team New Zealand will be shipping their AC75 to Barcelona next month to get some first hand answers.
The Joint AC37 Recon team assigned to follow the Swiss team noted:
"Another day of Garbi thermal wind; starting at around 9 knots and peaking at 14 knots. The sea state was relatively flat, with a slight chop towards the end of the session.
"The yacht was towed North toward the Forum, where sailing commenced at 12:30, with the M2-2L ETNZ Legacy mainsail and J3-1R jib.
"The team sailed five stints, warming up with a tack to bear away and downwind to upwind, then a long downwind to Masnou. On the exit of the sixth gybe, the yacht lifted up high and nosedived, tearing the J3 jib from the foot about the tack. A minor injury was sustained by a cyclor, and following safety procedures, was safely returned to base via Chase Alpha.
"A battery change was carried out, Nico Rolaz moved into the cyclor pod and the J4-1R was hoisted for sailing to resume sailing just under an hour after the incident. The team sailed upwind towards the 1.5NM windward/leeward course (no gates), and drilled manoeuvres and mark roundings for the remainder of the day.
"An eventful day, and despite the setbacks, ARBR were able to have their most productive day sailing on the AC75 in the last three weeks. 38 tacks/gybes were attempted, 68% fully foiling.
"The recon boat covered 51NM over four and a half hours on the water."
Nosedives/capsizes and other spectacular drama are not uncommon on the AC75. Indeed Emirates Team NZ nosedived the same boat, on its final sail in New Zealand at a speed that was a tad under 50kts. Although the boat did not resume the training session, it was not a catastrophic incident.
The sight of an AC75 going down the mine at 40-50kts is rather compelling, and takes the America's Cup into F1 territory.
The cause of the latest incident looks to be a flight control issue. It is hard to believe as claimed elsewhere that it was triggered by the two different wingfoils fitted (legacy wing foils from American Magic and Emirates Team New Zealand.) It is usual for AC teams to sail with different wing oils for testing purposes, and the Swiss have used this set for most of the sixty sailing days in the AC75.
Yes, their flight control has been off-key at times with the AC75 porpoising, particularly when sailing to windward. However it is believed that the team did not purchase a flight control system, with the AC75, preferring to develop their own, which was the correct decision in the medium to long term as they could develop their own software for the 2024 race boat, rather than be forever modifying Kiwi code, eventually turning it into some hybrid system which no-one liked.
The previous day in more stronger (17kts) and similar sea state (Beaufort 3-4), the Swiss turned in their most impressive performance to date, with great flight control, every little submersion and on the video at least, Alinghi Red Bull Racing's Boat 1, appeared to be sailing the same way it did as Te Aihe, by Emirates Team NZ in similar conditions.
The more believable explanation was that the AC75 suffered a series of flight control issues, resulting in the AC75 being allowed to climb too high on the foils. (Both wingfoils are styled around minimum span, as opposed to the wider span favoured by INEOS and Luna Rossa in the 2021 Cup). In the seaway the rudder elevator must have cleared the water, releasing its downforce and the AC75 nosedived.
The boat came to a complete stop, with the increase in stress spectacularly bursting the J5 jib. The AC75 reversed out of the nosedive before luffing and coming to rest.
The Swiss team attended to an injured cyclor, replaced the jib, and continued sailing after an hour long break.
One of these AC75 nosedives has never been captured before on video, and the clip below has been extracted from a six minute sequence shot by the AC37 Joint Recon team who should be commended on their tenacity, coverage and content.
The video clip is in high definition (1080p) and Cup aficionados interested in the practical aspects of monohull foiling, can use the settings control in Youtube, to slow the replay rate to quarter speed, and observe the incident frame by frame - from the time that the AC75 is sailing under full control, to the back out.
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.