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America's Cup: Emirates Team New Zealand reveal hard chine test boat

by Richard Gladwell/Sail-World.com/nz 23 Jan 2020 00:53 PST 23 January 2020
Emirates Team New Zealand launch their test boat - a 12Metre design that is very similar proportions to the AC75 used in the America's Cup. The hard chine hull will carry 3-5 crew © Richard Gladwell / Sail-World.com

Emirates Team New Zealand played a wild card in the 2021 America's Cup, with the launch of a 12metre (38ft) test boat in Auckland on Wednesday afternoon.

The launching took place in a team-only ceremony.

In 2018, the America's Cup Defenders elected not to follow the lead of three of the Challengers, whose first move in the current Cup was to launch prototype boats to both test the foiling monohull concept, and build a knowledge base for their first AC75.

Instead, the Kiwi team played to their strength and enhanced their already formidable design systems and simulator which had played a decisive role in the 2017 Cup win in Bermuda.

Emirates Team New Zealand's test boat, christened Te Kahu, will be used to plug a big gap in the team's sailing program, created by some unfortunate but unavoidable timing.

Design chief, Dan Bernasconi describes Te Kahu as "mainly as a development platform, to keep learning and experimenting through the year, whilst Boat 1 is on tour".

The Defender is now believed to have locked off many of major design decisions for its second AC75 - a milestone the Challengers passed several months earlier.

The team's first-born AC75, Te Aihe, is being decommissioned earlier than expected for a 60-day voyage to Cagliari, Sardinia, venue for the first America's Cup World Series Regatta in late April.

Standout feature of Te Kahu is the chined hull, which sits very comfortably with older Kiwi sailors - given the historical links back to top designer and builder John Spencer, a strong advocate of hard chine racing boat designs and their ease of construction.

Emirates Team NZ design chief, Dan Bernsaconi admits the team opted for a hard chine hull because of the ease of construction, but also notes that the style would be also legal under the AC75 rule.

"We wanted to concentrate 100% on getting that first boat right," Bernasconi said. "We thought there would be more value for us in having a "1.5" - halfway between (the AC75's) Boat 1 and Boat 2. This boat is a stepping stone to what we want to do next time," he added.

The test boat Te Kahu (named after the NZ harrier hawk) will sail with 3-5 crew instead of the 11 required for the AC75. A self-tacking jib is one indication of a break with the otherwise closely scaled version of the 75fter.

Te Kahu does little to indicate the direction of travel that the New Zealanders will take with their design for the second AC75.

Her main role will be to test further options with systems, appendages, foils, sails - almost everything other than hull shape. Promising developments can then be taken across to the two full size AC75's.

Under the class rule for the AC75 a number of components, such as wings, are restricted in number. Undertaking development on the prototype skirts around these AC75 restrictions allowing more options to be trialled and the successful ones promoted to the race boat.

ETNZ remains an AC75 class outlier with the choice of full width wings without a bulb or fuselage. "There are pros and cons," explains Bernasconi. "Without a bulb, you need thicker wings to enclose the same amount of volume and achieve the same total weight. Thicker wings are a disadvantage in performance, but so is the extra wetted area of a bulb."

Getting a definitive answer to the wings question may be on the worklist for Te Kahu and the design team.

Because of the size difference between AC75 and the 38ft test boats Emirates Team New Zealand have not been to work the same angle they did in June 2016 with the launch of their test AC50. There they were again the last team to launch a test boat, and used a metre-long rudder gantry off the back of the permitted AC45 hulls to get very close to the foiling geometry for an AC50. The ETNZ test boat used AC50 sized crossbeams and wingsails effectively gaining an extra six months full size testing on the water.

This time, "there are no common components except some of the electronics and some of the crew," says Bernasconi.

Of the four AC75's launched - INEOS Team UK and NYYC American Magic opted for a scow shaped hull, while Challenger of Record Luna Rossa and Defender Emirates Team New Zealand both opted for skiff hulls.

Which type is better may be answered at the first of the two America's Cup World Series Regattas. However INEOS Team UK skipper, Ben Ainslie in a recent podcast published by Yachting World admitted a hankering for the Luna Rossa hull shape with her "V" skeg.

Ainslie claimed that the UK team had used a process knows as photogrammetry to build CAD models of the three other teams designs and could then run those against their performance analysis tools.

"The design of the Italian boat is a more aggressive boat than the New Zealand boat. I think that once it is out of the water it can be a really strong boat. I really liked a lot of the ideas on the Italian boat. They have pushed the boundaries on creativity which is really cool to see."

He added that both the Defender and Challenger of Record may have had a better and earlier knowledge of the AC75 rule than NYYC American Magic and INEOS Team UK. Ainslie says the British and US teams orientated their first designs around displacement sailing and using the hull form to get the AC75 foiling as quickly as possible.

While the Auckland spring and summer sailing weather have not been as expected - with substantial periods of strong winds, and more recently several days of light airs, Bernasconi says they have made the most of the time available - working some long days on the water.

"We never stop learning with the boat, so when conditions are good and the boat is going well, everyone is keen to keep pushing and learning more. Time is short, and we all want to make the most of it," he said.

With technology and communication improvements for this campaign in Auckland, Bernasconi confirmed ETNZ's designers/engineers did have the ability to make software changes to the systems aboard Te Aihe, working from the team base in the Viaduct Harbour while the boat was on a break between test runs in the Hauraki Gulf.

Bernasconi wouldn't make any comment about changes made to the AC75. Te Aihe is conspicuous for her above deck simplicity, leading to the conclusion that bulk of the systems lie below decks.

Olympic juggling

Two Olympic campaigns are running within the ETNZ America's Cup program. Indeed the team can boast of two current World Champions in their respective Olympic classes - the 49er double-handed skiff and the singlehanded Finn class.

The four sailors involved have 2020 world championships coming up in February (49er) and May (Finn) interspersed with training plus build-up regattas in Europe ahead of the Olympic Regatta in Enoshima, Japan starting in late July.

Against that backdrop of other sailing commitments and timing the Kiwi team would have had to draw on a wider sailing squad, if it were possible to take advantage of the summer and autumn sailing season in Auckland using their first built AC75.

Regardless of how she performs in Sardinia and Portsmouth, Te Aihe will always be remembered for being the first AC75 to capsize, preceded by a spectacular leap skyward where the boat cleared the water at a launch angle steeper than a commercial airliner on take-off.

Remarkably there was no structural damage to the Kiwi's AC75, and she continued sailing for a four hour session in fresh breezes, after being righted.

Bernasconi says the lift-off and capsize, just off North Head, at the start of her final sail before the Christmas break, wasn't part of a prescribed test plan.

"It wasn't planned, although we had carefully rehearsed on paper what we would do in the event of a capsize - which we expected to happen at some point."

"The crew are not tethered in, but with the relatively deep cockpits it's quite easy for the crew to hold themselves into the boat," he added.

In the two previous America's Cups, there was plenty of talk of nosedives with the wingsailed foiling catamarans - and there were some spectacular incidents in both the 2013 and 2017 America's Cup cycles.

In the 2021 America's Cup buildup the word "nosedive" has been replaced by "splashdown" - and spectacular they are too. On the AC75's Emirates Team NZ are the only ones to have been caught on camera.

With the AC50 there was always a degree of trepidation as the boat went through the "Valley of Death" as the boat accelerated rapidly during a turn downwind. Does this situation occur to the same degree with the AC75, we asked Bernasconi.

"A bearaway from upwind to downwind is usually when the highest speeds are reached, and when some parts of the boat are the most loaded," he replied.

"So it is a manoeuvre that is considered right from the start of design in any high-performance foiling yacht – and one which is certainly approached with care when sailing."

"There is not a huge amount of difference between the behaviour of an AC75 and an AC50 in this respect."

Quite what will happen on the racecourse with the high-powered AC75's remains one of the most intriguing questions of the 36th America's Cup.

Currently Emirates Team New Zealand are involved in decommissioning Te Aihe and doing the pack out for the two America's Cup World Series regattas. Once that process is largely complete, Te Kahu is expected to make her debut on the Waitemata.

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