Cup Spy: Cup champions test out the AC40 performance edges at 45kts - Day 5
by Richard Gladwell/Sail-World.com/nz 30 Sep 2022 19:55 AEST
30 September 2022
AC40 - Emirates Team New Zealand - Waitemata Harbour - September 30, 2022 © America's Cup/Adam Mustill
Emirates Team New Zealand's champion America's Cup crew found the limits of the AC40, the hard way, triggering the first serious capsize and setting a new top speed mark of 45kts.
Five of ETNZ's sailing team were aboard - Nathan Outteridge, Andy Maloney and Josh Junior - all driving and with Peter Burling and Blair Tuke listed sail trimmers.
"For me, it was my first day on the boat, and it was great to be to be able to hop on the wheel and drive it," said double America's Cup winner and Finn Gold Cup champion Josh Junior interviewed ashore.
"Just to feel the speed and how easy everything's working is really cool," he added.
"Now it's all about pushing harder and finding where the limits are. It's been a been really cool day."
Today was the end of the second week of sailing in the AC40, in which two different crews have sailed. Today's crew Burling, Tuke, Junior and Maloney were on SailGP duties last week in Cadiz.
"It's an amazing boat. The team has done a great job putting the boat together and getting it on the water. We've now done three or four days of pushing the boat really hard," Josh Junior explained. They were joined by Nathan Outteridge.
"Unfortunately, we did have a capsize today," he confessed.
"We started to push the boat a little bit harder. We've started to jack it up or get higher on those foils. And, by doing that, when you do a bear away, the rudder gets much closer to the surface. And if you don't quite get it perfectly right, it cavitates, and you're into a bit of trouble."
"So that happened to us today. It's about finding that edge and continuing to learn the boat, as it's the one design class, we need to find out where those limits are, and how hard you can push them."
"It's good for us to learn those limits."
The critical point on any America's Cup foiler comes when the rudder unloads if it breaks the surface by lifting too high on the main foils, or by breaking out while sailing through a wave, or ventilating in some way.
Whatever the reason, the outcome is the same - a full face-plant which is sudden and spectacular, as the boat 'trips' over the main foil arms and nosedives.
American Magic demonstrated this feature of high performance foilers early in their 2021 America's Cup campaign, when their test boat "The Mule" rose high on its foils and face planted, as soon as the rudder aileron exited the water, and stopped applying a lot of downward pressure on the aft end of the boat. In AC50's used in the 2017 America's Cup this downward load was around 500kg. A significant downward pressure. In aeronautical terms it is the same as if an aeroplane in flight had its tail drop off.
It is not known if the crew were flying on automated flight control, or were running it on manual to force the AC40 to foil high. On previous test days the crew have been testing the automated flight control, trying to "break" it while sailing in waves.
Unfortunately for Cup fans, the Recon team were changing storage cards in their camera and missed the nosedive sequence.
The rest of Day 5's test sail was routine if that term can ever be used in the AC40 context. A couple of jibs were tried.
"We had the #3 out for most today. It was pretty windy out there, and the boat was really ripping around," Josh Junior said.
"Then we checked in on the #2 jib.
"We haven't hoisted many of these sails that often, so we're just checking the geometry and ensuring everything's in the proper position.
"It's been a really good day just of ticking things off and learning the limits," he added.
The other significant achievement was hitting 44-45kts of boat speed - which is quite remarkable given that 45kts was the top-end speed predicted by the design engineers when the AC40 concept was first announced.
Hitting that target speed with the AC40 sailing in one-design mode is quite an achievement. It compares favourably with the 53.31kts set by American Magic's AC75 Patriot in the Semi-Finals of the 2021 Prada Cup and the 54kts set by the French SailGP team in Saint-Tropez in late July.
"The boat's really going really well," Josh Junior said in a concluding understatement.
Today's test was conducted in an NNE (onshore sea breeze), recorded by Predictwind's observation function as puffing to around 15kts.
It sent a clear message to the Youth and Womens crews wishing to compete in their two America's Cup regattas that the AC40 will certainly showcase their skills. But it will also punish their mistakes most spectacularly.
Session Statistics - Auckland October 7, 2022 - Emirates Team NZ - AC40 in One Design mode
- Wind Strength (PM): 10-20 knots Wind Angle: NNW
- Current: Outgoing
- Dock Out: 11.45 (Dock In: 1600)
- Total Tacks: 17 – 16 foiling, 1 splash down and go Total gybes: 9 – 9 foiling
- Helms: Nathan Outteridge, Andy Maloney, Josh Junior, Crew: Pete Burling, Blair Tuke
- Sails: M1 (used for 3.5 hours) J3 (used for 20 mins) J4 (used for 3.2 hours
- Upwind VMG: Stable and pointing high 45-50 true wind angle
- Downwind VMG: A little unstable in ride height, however fast most the time
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