ETNZ launched its first AC75 in Auckland in September. She’s a wonderful sight – sleek, racy, oozing attitude – and very other-worldly. But it’s hard to come away without pondering the delicate knife-edge on which this keelless monohull will fly.
The launching was a significant milestone – giving the world the first view of a full-size AC75 since the concept was unveiled in November 2017. It created quite a splash then – I suspect the ripples now have fresh impetus.
There’s plenty to digest: foremost among her features are those dangling, S-shaped arms with their sweeping, Batman-like foils – and the slim T-foil rudder which seems way too fragile for controlling the pitch on a 75-footer flying along at a projected 50 knots.
Equally intriguing is the cockpit arrangement – twin ‘boxes’ separated by a fair bit of real estate. How does the crew shimmy across during tacks and gybes? And what about that sweeping sheer? Viewed from the side, the deck profile from bow to stern looks uncannily like the ‘chord’ of an aircraft wing. Is the intention that at 50 knots even the hull will generate lift, helping to keep the boat on her foils?
So, plenty of questions and unknowns and much for the team to embrace – and quickly. The first event in the America’s Cup World Series takes place in Sardinia in April next year. When this vessel embarked on her maiden sail in September, it was the first time the team had collectively sailed since winning the America’s Cup in June 2017.
Other teams in the 2021 America’s Cup – INEOS Team UK, Luna Rossa and American Magic – have now also launched their boats. The fourth challenger – Stars and Stripes Team USA – is evidently not yet at a ‘launch point’.
THE AC75 CLASS RULE
This 75-foot, high performance monohull is governed by the AC75 Class Rule (published on 29 March 2018). The Rule is sufficiently flexible to guarantee a wide margin of freedom to the designers but also introduces certain one-design elements for cost containment.
The AC75 supplied parts – identical for all the teams – are the foil arms, the foil-cant system and the rigging. The shape and base laminate of the mast is also controlled by the Rule. The rotating mast is a 26.5m one-design D-shaped section that weighs about 300kg and serves as the leading edge of the doubleskinned mainsail. ETNZ’s mast has been built at Southern Spars in Auckland whereas the rigging package was built at Future Fibres in Valencia.
The two other one-design components are central to making the boat fly. The foil arms, built at Italy’s Persico Marine, are the result of a project led by Luna Rossa Challenge with the collaboration of all the America’s Cup teams and New Zealand-based composite engineering consultancy Pure Design and Engineering. Each 4.5m carbon foil arm has a wing attached to its tip. Foil wings are custom-designed and built by each team.
Driving the foil arms is the electronic and hydraulic foil-cant system, another one-design supplied part. It moves the arms and wings in and out of the water. The foil-cant system was designed by ETNZ and assembled in Auckland before being distributed to all teams earlier in the year.
The rest of the Class Rule is open and, being a new concept, leaves the design quite free as no proven path has yet been defined for these types of boats. Any ‘shrouding’ of the yachts is prohibited so teams won’t be able to hide their different design approaches and subsequent developments.
The most visible differences will be seen in the hull shapes and deck layouts. Despite a number of basic constraints such as the length, the hull has few significant limits on shape or structure. Design teams will be looking for a shape with minimal drag in light-wind displacement mode while also addressing the stability required to generate thrust for take-off.
Evident differences will be displayed also in the foil wings and wing flaps as they are also open to design and, being T-style foils, their shapes have been less explored than the L- foils used in the last two Cups.
The double-surface mainsail – a new innovation – will be key in the performance of the boat and many hours have been invested in its design.
The hydraulic and electronic control systems, powered and controlled by the crew, operate key components of the boat such as the foils and they have been subjected to important developments as well – but remain a very guarded secret by each team.
America’s Cup racing has always pushed the envelope – it’s a given. And if the foiling catamarans were a major departure, foiling monohulls takes the discussion into a completely different realm. “This is not just because it is another new boat,” says ETNZ chief operating officer Kevin Shoebridge. “When we won the America’s Cup in 2017 we quickly had to come up with a new concept of boat that would continue to push the boundaries of innovation and technology.
“So in the relatively short timeframe since November 2017 – when we published the concept – to seeing it in the flesh today is an amazing testament to the entire team willing to push things all the way from concept to design to build and fit-out.”
Led by ETNZ stalwart Sean Regan it has taken more than 100,000 man-hours to design and build the boat at the team’s bespoke production facility on Auckland’s North Shore. The team comprises about 65 people.
“Even for the most experienced boatbuilders on the team,” says Regan, “this has been a unique build because it’s such a sophisticated boat. But it is really encouraging that for a number of our junior and apprentice boatbuilders their first build has been on a boat that is really on the cutting edge of complexity in build, design and performance.”
ETNZ head of design Dan Bernasconi played a central role in the development of the AC75 Class Rule before turning his team of designers’ attention to the new boat.
“There’s a huge amount of innovation in the design and build of the AC75 – more than we saw in the AC50s in Bermuda,” he says. “The AC75 has presented plenty of challenges across many areas – but this is precisely what the Rule was designed to do – to push development to the extreme.
“We haven’t been conservative in any aspect of our design; it’s not long until we need to commit to the design of our second boat, which we will ultimately race in the 2021 America’s Cup, so we need to test as many of our ideas as possible in the yacht we’re launching today.”
Unlike the other main challengers, ETNZ has focused the development of its first boat entirely with its in-house simulator, rather than build a smaller-scale test boat to validate concepts on the water.
“It won’t be without nerves the first time we go sailing, but I am sure that is no different for all of the teams,” adds Glenn Ashby. “The AC75’s are big, powerful and fast boats so they will be a handful, but from our understanding through our simulations they are inherently a safer boat to sail than what we have sailed in the past two America’s Cups.
“As with any new boat it is all about slowly getting it up to speed, learning how to sail it most efficiently, pushing the development of the designs and then putting in the hours in getting ready to race in Sardinia in April 2020.”
ETNZ is now focused on testing the boat on Auckland’s Hauraki Gulf over the spring and summer months, having the advantage of developing and training on the race area of the America’s Cup to be raced in March 2021. Her performance will provide vital information as the team begins to make refinements for the second race boat.
The boat has been named Te Aihe (Dolphin), and stems from the whakatauki (proverb):
“Mā te Aihe e tuitui ai i te ngaru moana, mā te Rangatira e tuitui ai i te tangata”.
“As the dolphin sews through the seas so does a leader sew people together”.
May she leap and fly with the dolphin’s grace and agility.
