ETNZ's lead designer Dan Bernasconi comments after a ride on the AC75

After a week of, at times, monsoon rain that yielded to persistent inclement weather patterns and strong breezes out on the Hauraki Gulf, Emirates Team New Zealand had a sense of relief as Friday produced near-perfect conditions to take to the water in ‘Te Rehutai’ – the Cup winning boat, much modified, from AC36.

Crane in was early and super-smooth and the on-dock briefing from Ray Davies was short and to the point - this was to be a long day for the sailors and cyclors to hone their transitions, communications and technique. Once out of the Wynard Harbour entrance, the big M1 mainsail and J1 jib were locked into position and the team sat at tow getting the settings perfect before the chase was dropped and Pete Burling steered off on starboard tack hoping for a speed build with the breeze bouncing off the Auckland cityscape and tower blocks. It wasn’t to be, and the call came in for a tow down the harbour channel where ‘Te Rehutai’ quickly took flight and once clear of the commercial docks, was up and foiling with immense power on display.

As quickly as it started, it stopped just off the Devonport Pier. A mainsheet traveller bearing issue saw Chase2 head back to shore for supplies and the full team set to work on a repair. Impressive to watch, the ‘team’ mentality was on full display with everyone mucking in to get the issue fixed ASAP. Some 15 minutes later, Te Rehutai was back on her foils, blistering down the left-hand harbour turn, gybing and then flying out downwind towards the Eastern Coast Bays in 10-11 knots of breeze. Once past the red and white Rangitoto Light, and down to the southwest in clear waters, the boat came to a stop and took the author of this piece onboard for a highly memorable session.

The wind and sea-state gradually built, and Pete Burling and Nathan Outteridge had ‘Te Rehutai’ at the max, performing some impressive bear-aways up at Rangitoto and flying back downwind on the gybe angles towards Castor and Murray Bays. Round-ups were seriously fast as the crew pushed through a number of trim tweaks going from leeward heel to windward heel with Blair Tuke and Andy Maloney doing a stellar job to keep the boat flying through a myriad of foil-to-foil tacks, not dropping off the foils once.

With the sea state building to almost white tops and a solid 14 knots of breeze, the onboard comms started the conversation about changing down to the M2 mainsail and smaller headsail. It was a wise call, and the team brought the AC75 to a stop with the team taking the opportunity to re-fuel, rotate grinders, re-instate battery power and do a full sail change.

The opportunity to sail on a single day with two mainsails was highly valuable to the team as Dan Bernasconi, the lead designer for Emirates Team New Zealand, who also had a ride on the AC75 in the afternoon, commented afterwards: “Yeah it was good to see the range of conditions through the two mains, not that often you get the opportunity to sort of test them back-to-back in flat water where you can pick out the differences so yeah really, really, valuable day for us. It’s one of the last days we're going to have in the AC75 before we go to Barcelona… I don't get to go on the yacht very often so it’s good to check in occasionally, it’s bumpy, it’s noisy, extremely uncomfortable, yeah I wouldn't really recommend it…but it’s really cool and it is valuable to remind yourself, get away from the computer screen and remind yourself of the reality of it every so often. And there's always things that you notice that you haven’t really thought of, good opportunity to look at the foils first hand and actually sort of experience the movement of the boat which is something you don't really pick up so much from the chase boat. When you're looking at the boat from off the boat it looks like it's very smooth but there’s actually quite a lot going on, and quite a lot of movement and changes in leeway, the boat goes from side to side to quite a lot as the foils rise and fall.”

Dan was then asked about what we can look forward to, design-wise in AC37 in Barcelona and he gave an interesting response, saying: “I think there’s plenty of space in the rule, we've been looking at a real big range of hull shapes and the parameters have changed a bit from last time, there’s several things in the rule which have changed, the new stability constraints, the weight change, there's no runners, you know quite a lot of things which change the overall design parameters of the yacht. Obviously, I’m not going to say where we're heading towards, but I think there is scope for a range of different shapes, and I think probably we’ll see again in Barcelona 2024 reasonably big differences between the boats still. I don’t think we're going to get to that point where they all look identical because you know there are trade-offs, and you have to make decisions on those so it’s hard to guess exactly which way everyone is going to go.”

And after the reveal of the new Alinghi Red Bull Racing foil, Dan cast his designer’s eye and deep America’s Cup knowledge over it saying: “Really interesting. That sort of concept of the dimpled leading edge has been talked about over the years, there are some marine life with that characteristic and there's some theories about potential gains on it, so it's really interesting to see Alinghi Red Bull Racing try that. It looks really cool. Nice paint job as well.”

Emirates Team New Zealand have one further day of AC75 training in Auckland left and may well have a quick blast in their AC40s next week before the boats are loaded onto a ship and sent to Barcelona. It has been a valuable antipodean summer in Auckland for the defenders and today, the 18th day with Te Rehutai on the water, was another cracker.