America's Cup: Challenger and Defender explain some of their secret weaponry
by Richard Gladwell / Sail-World NZ 10 Mar 2021 10:39 AEDT
10 March 2021
Emirates Team New Zealand & Luna Rossa Prada Pirelli - Practice Day 1 - ACWS - December 8, 2020 - Waitemata Harbour - Auckland - 36th America's Cup © Richard Gladwell / Sail-World.com
The America's Cup Challenger and Defender both revealed some of the new developments yesterday in a short separate interviews, with Sail-World, in the Mixed Zone at the Prada Media Centre.
Emirates Team New Zealand helmsman Peter Burling elaborated on the team's new Code Zero, which has recently made a few appearances.
The sail is different from the standard Code Zero, which every team tried and was treated much like a big jib, capable of being sheeted hard.
"The new Code Zero is really a sail to allow us to try and finish races where the breeze has died down," Buring explained.
"Like the Xmas Cup one against INEOS - where the breeze completely died, and we couldn't get down the last run in time."
"It's there as a weapon to combat that situation," he added.
He's coy about the cloth weight of what is essentially used to be known as a [light air] floater, other than to say that compared to a standard AC75 weight. "It's definitely quite a bit lighter," is all he will say.
The cut of the Code Zero floater is quite different from the standard Code Zero - set part-spinnaker, part-jib. The key difference between the standard Code Zero - which has not been used yet in an America's Cup or Prada Cup race - is that the Code Zero floater seems to be able to be furled like a regular furling jib, and without the line-up of support crew on the foredeck to tight furl on the regular Code Zero.
Again Burling is rather coy about its use.
"It is a lot more downwind oriented sail - you can do what you like with it, put it up, put it down, furl it", he explains. Video of the sail shows the AC75 transitioning from sailing at displacement speed with the Code Zero floater, furling the sail and then foiling with jib set and the Code Zero furled.
The use of a lightweight cloth means that the Code Zero floater furls a lot thinner than the regular Code Zero, which is quite a thick furl, and creates a lot more drag when furled than the thinner floater.
It also seems that unlike the regular Code Zero furler the floater can be set from within the boat, while the practice has been to set the Code Zero with furler attached, lace the tack onto the bowsprit in some way, and then remove the furler. That process has to take place about 10 minutes before the start of a race, and because of the way that it is set up, the sail has to stay in place for the duration of the race.
The Emirates Team New Zealand system would appear to have overcome both of these issues, and gives the team another option in its light weather rigs. The Code Zero floater is flown from the bowsprit, without a lot of luff tension, and has the regular jib set inside it - which is the other big difference from the standard Code Zero setup, which has the jib removed from the forestay.
Anyone for a Batwing?
Emirates Team New Zealand have also been spotted sailing with a Batwing mainsail - following the lead of American Magic, which tried two of the sails, notable for their hollow cut leech and protruding batten ends - which give the sail the appearance of a "batwing".
It seems that the Jury is still out on the merits of the batwing mainsail as far as Emirates Team New Zealand is concerned.
"The upper-end wind limit is quite high," explains Burling. "We wanted to check in and see whether it would be an advantage to have a slightly smaller mainsail.
"We haven't fully decided where our cross-overs are with our mainsails - so you'll just have to wait and see if we use it or not."
The speculation is that the team can reverse the head of the batwing mainsail to produce righting moment.
Burling ducks the question. Either it is a silly one, or he doesn't want to say. "We can do a lot with our mainsails and the range we get out of them."
Luna Rossa's hidden main boom
For the past week or so, the speculation has been that Luna Rossa which appeared to have a floating clew mainsail, like Emirates Team New Zealand, instead had a mainsail boom, but it was below the curved cockpit deck, which lifts off like a cowling.
"Probably the biggest mistake we made was to be too good with the first boat. But that is part of the game," is Sirena's initial comment to the boom question.
"We pushed hard on aerodynamics from the very beginning. The [below decks] boom was always there. It was part of the design and thinking for Boat #1. We didn't want a boom swinging across the boat when we were sailing at 40kts.
"We always believed that Boat #1 could be used as a racing boat. We had the same boom setup on Boat #1 as well," he reiterates.
Before the Prada Cup Finals, the Luna Rossa skipper, came into the pre-series media conference with a list of new developments that had been put aboard Luna Rossa. They included new sails and a new mast, prompting the question that they had gone away from their backstay-less set used in the America's Cup World Series, and were now carrying a lot more rig and cunningham tension to induce pre-bend.
"We have made a lot of improvements all around it is obviously not just the rig, it is the systems - how fast and how well you can adjust the boat for the conditions. Plus the aerodynamics and sails," Sirena noted.
"Sails are huge", he adds, without elaborating.
However one of the many challenges of the AC75 is that the sails have to be powerful enough to work at normal windstrengths to get the monohull foiling, but then have to be capable of being flattened, without stretching, to be able to sail in 50kts of apparent windspeed.
"We are just at the beginning of this AC75 class," Sirena says, reflecting on the fact that the first AC75's were only launched in September 2019, and had not sailed a race until over a year later in December 2020.
"Every day we try something new and get performance gains," he says. "We are just at the beginning of the era with this class, and I hope we keep going with this boat", he adds.