america's cup foiling catamaran

THE BOATS: AC75, AC40 & LEQ12

Although foiling feels like a recent revolution to take the world of watersports by storm, it has been at the heart of America's Cup racing for over 10 years.

It was August 2012 when the sailing world was turned upside down by a 72-foot catamaran flying in the Hauraki Gulf. Emirates Team New Zealand had brought foils to the America's Cup, changing the face of top-level yacht racing forever.

Six years later, in 2018, the publication of the AC75 Class Rule marked the beginning of a new sailing era. The engineering and sailing techniques needed to get the AC75 to fly completely differed from anything seen before.

During the 36th America's Cup in 2021, the AC75 proved themselves to be unique and kept millions of fans worldwide glued to their screens. It was then no surprise that the organisers were keen to continue with the AC75 rule for the Louis Vuitton 37th America’s Cup in Barcelona, albeit with several improvements to promote faster flight and incorporate upgraded technology. But the organisers went further. With a focus on youth and women being paramount to growing the sport into the future, a new class of boats was introduced–the AC40–specifically for this purpose. As the smaller sister-ship of the AC75, the AC40 launched in Auckland to much acclaim with speeds hitting the "high 40s" almost immediately straight out of the box under the skillful command of Emirates Team New Zealand in September 2022.

AC75: AMERICA'S CUP BOAT

On the 15th of November 2021, eight months after the Kiwis successfully defended the America's Cup, an updated 'Version 2' of the AC75 Class Rule was released.

The boats will be a step on from what we saw in Auckland in 2021. The foils will be larger to promote quicker lift and faster flight. The boats will be lighter and, onboard, the electronics and software systems will be vastly upgraded. To save weight, the number of crew on the AC75 has been reduced from 11 to 8. The move to reduce the crew means cycle power is again legalised, and the cyclors, introduced by Emirates Team New Zealand in 2017, might return to the game.

Several of the elements are strict one-design, such as the mast, rigging, foil cant-arms and cant hydraulics but the scope for design elsewhere is broad. To keep costs under control, it was also determined that teams would only be allowed to build one AC75 so the demand on getting the design right is at a premium. The boats will be expected to fly at speeds of 50 knots (with a record speed reported of 55.6 knots during racing) in winds that average 12 knots in late summers in Barcelona. 

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AC40: YOUTH, WOMEN & TRAINING

New for the Louis Vuitton 37th America's Cup, the AC40 is a multi-use foiling monohull that all the confirmed teams will use for sailing and testing purposes. The AC40 is also the nominated boat for both the UniCredit Youth & Puig Women’s America’s Cup events where they will be sailed in strict one-design. The confirmed teams will also use the AC40 in competitive events leading up to the America’s Cup and several of the teams have two boats on order. The AC40 is being built by McConaghy’s in China. The foils and systems are being delivered by the Emirates Team New Zealand North Shore Facility and delivered in strict order of entry to the America’s Cup. Teams may modify and test out componentry on the AC40, and for this purpose, they will be deemed as a LEQ12 (see below), but for competition purposes in the UniCredit Youth & Puig Women’s America’s Cup, they will be returned to one-design according to strict rules around those specific events. Early trials of the AC40 by Emirates Team New Zealand have been sensational with speeds recorded in the ‘high-40-knot’ bracket and it is anticipated that this new class will form a global circuit both before and after the America’s Cup. For the UniCredit Youth & Puig Women’s America’s Cup, aside from the confirmed entries from the America's Cup syndicates, yacht clubs from around the world are being invited to form teams on a strict one-nation, one-entry basis and the finals of the youth and women’s events are scheduled on key dates of both the Louis Vuitton Cup (Challenger Selection Series) and Louis Vuitton 37th America's Cup Match dates.

LEARN MORE ABOUT THE UNICREDIT YOUTH AND THE PUIG WOMEN'S AMERICA'S CUP

LEQ12: TESTING ONLY

Entrants for the Louis Vuitton 37th America’s Cup are required to build one AC75 and purchase at least one AC40 but within the rules there is also the opportunity for teams to build one, new, test boat with the stipulation that it must be ‘Less than or Equal to 12 metres in overall length.’ The term LEQ12 was thus coined and it’s a nod to a well used term in computing ‘LEQ’ and was the most accurate description of the vessel. These boats are loaded with sensors, cameras and measuring devices in order that the design team can collate data and calibrate their design software packages in a real-world environment. For the sailors too, it is an opportunity to hone monohull foiling techniques and have the ability to try new sailing styles as well as test new componentry in a relatively controlled environment–with far fewer consequences than trialling something new on a powerful AC75 at full scale.

How many new AC75s can a team build

When agreeing on the new format for the 37th America’s Cup, the Defender and the Challenger of Record were determined to keep a lid on costs and deliver a sustainable event that could attract additional entries without a very high financial barrier to entry. During the 36th America's Cup, teams were allowed to build two AC75s but in the final Protocol for the 37th America's Cup, it was agreed that teams could only build one AC75 to compete in the America’s Cup in Barcelona. The introduction of the AC40 class allowed for teams to purchase these for either two-boat training or as test boats and a further concession was permitted in that teams could build one specific LEQ12 for testing and training purposes. By implementing the one-boat build rule for the 37th America's Cup, a high premium is placed on getting the final design right as there is little opportunity to change the fundamental design of the boats after launch. The world’s greatest naval architects, designers and engineers have been employed by all the teams with several partnering with complementary sports engineering functions such as Red Bull Advanced Technologies and Mercedes F1 Applied Science. The design race for the Cup is therefore, as intense as ever.

Can older AC75s be used and/or modified?

The first-generation AC75s that were used at the 36th America's Cup in 2021 may be used for training purposes by all of the confirmed teams in the run-up to the Louis Vuitton 37th America's Cup in Barcelona. To date, two teams–American Magic and Alinghi Red Bull Racing–have opted to re-launch these first-generation boats and use them as test boats and in the case of Alinghi Red Bull Racing, the Swiss who were not present during the 36th America's Cup, purchased Emirates Team New Zealand’s first boat ‘Te Aihe’ to train in Barcelona. There are, however, strict rules on developing these first-generation boats with the number of foil wings, flaps, rudders, foil arms, masts, hull surfaces and sails being strictly limited. This could well be the reason why the other teams have elected to develop LEQ12s or to adapt their AC40s into LEQ12s, as is the case with Emirates Team New Zealand, where the limits on componentry and testing are far less stringent, affording more scope for design development and analysis.

When does an AC40 become an LEQ12?

As mentioned above, in relation to the AC40, these boats are delivered in one-design format, but some teams may elect to take them out of one-design to test out componentry, and in this case, those AC40s will be deemed as ‘LEQ12s’ until returned to one-design configuration again. Change anything on your AC40 outside of the very strict class rules on componentry, and it becomes a LEQ12. In order for it to be used in the planned pre-regattas or the UniCredit Youth & Puig Women’s America’s Cup events it must be returned to the agreed one-design. Immediately after the necessary commissioning process of the very first AC40 that was delivered to Emirates Team New Zealand in September 2022, the team made changes to the cockpit configuration and specific controls that the crew use; This immediately converted the Emirates Team New Zealand AC40 to a LEQ12.

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America's Cup - Dan Bernasconi explains the foiling AC75 - Part 1

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Eagle Class 53: The foiling cruiser inspired by the America’s Cup

• Matthew Sheahan
• August 6, 2019

Is this the future of sailing? The Eagle Class 53 is a wingmasted cruising catamaran designed to fly on T-foils

Not everything that flies is destined to scorch around an America’s Cup course. The future for sailing hydrofoils is surely about more than just racing. At least, that was the view of one owner who, having witnessed the America’s Cup foiling catamarans, saw a big opportunity.

“I’ve worked as a skipper for yacht owner Donald Sussman for 16 years,” says Tommy Gonzalez. “When he saw the foiling Cup boats he knew that this was what he wanted to have a go at. He is not interested in racing himself, he wanted to go cruising, but cruising on foils. He saw what had been created and believed that this had practical potential. Put simply he said: ‘I want one and I want to be the first.’”

As well as being a professional skipper, Gonzalez is the president of Fast Forward Composites, a Rhode Island-based composite building facility where the Eagle Class 53 was constructed. Understandably, the road to creating such an ambitious cruiser was never going to be straightforward. So the plan was structured around several key elements and stages, starting with an efficient and easily managed wingmast.

The hybrid solid wing and soft sail configuration means the rotating rig can be reefed. The entire solid wing can be rotated through 360° ensuring the rig can always be fully depowered – important for docking and close quarters manoeuvring

Of those two criteria, efficiency is easy to satisfy – wingmasts are by definition more efficient. It is the practicalities of handling them that usually causes problems. Reducing sail in breezy conditions and leaving the wing up at the dock are two of the biggest issues.

The solution on the Eagle Class 53 was to create a composite wingmast where 50% of the area is a solid D-section and the trailing 50% a soft sail that can be raised, lowered and reefed. Interestingly, it is a similar concept to that of the next generation of 75ft foiling monohull Cup boats, currently under development. “The rig is a little lighter than a conventional mast and sail set up, and significantly easier to handle,” explains Gonzalez.

“Because the sail can be raised or lowered we can reef the main, or even just sail with the solid section. The mainsheet loads are around 40% less than a conventional rig and because the sail can turn 360° we can let the wingmast fully rotate, which makes life simple when you’re docking. You just let it feather.

“In addition, because we have a part soft sail, which we have developed with North Sails, we can create twist which allows us to de-power the top of the sail, so we have plenty of control over this wing and the advantages that go with it.”

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The next stage was to work towards foiling. To do this the team decided to create a cat that had C-section daggerboards that would help reduce displacement at speed but not lift the boat entirely. Getting used to controlling the power and feeling the behaviour of the boat through various wind ranges and sea states would provide a solid understanding of the boat’s characteristics.

“Once we have got used to the way the boat handles, the next stage will be to fit T-foil rudders which will take us onto the next level,” continues Gonzalez. “With these we will be able to get used to the software system, the instrument displays and the feel and the control of that part of the programme without taking the boat to full flight.

“That will allow us to get her up on her toes like a ballerina and keep her there so we understand what she feels like before she flies. “After that, in the spring next year, we’ll remove the C-foils, put on the T-foil daggerboards with their elevators, and move on to full foiling.”

The wingmast has a solid D-section and trailing soft sail

The proposed T-foil daggerboards will be angled out which makes the overall platform slightly wider, which in turn makes for more stable and efficient foils. And while improving the efficiency of the lifting surfaces, the outward bend in the daggerboards will also help to generate more righting moment, and hence achieve greater stability.

The control system itself will be a form of fly-by-wire system that will allow autonomous flight to ensure that the boat sails within safe operating limits. “If you have some of the gods of sailing aboard you will be able to override the controls to some degree, but under normal circumstances the control system will automatically de-power and lower the boat back into the water when the speed gets to 35 knots,” he explains.

So far the project has gone well. After the boat was launched earlier this year she cruised in the Caribbean during the regatta season before heading north back to Bristol, Rhode Island. “We’ve been very pleased with how well the boat sails and how easy she is to handle,” said Gonzalez.

“When we’re on delivery trips we have just three aboard. Aside from myself, the other two crew are not highly qualified professional sailors and yet we are looking at boat speeds of around 15-18 knots upwind and then 22 knots off the wind.

“We have also been through a squall of 35 knots where we were sailing with just the D-section of the wing mast which was easy to control by feathering the wing. When we get to the foiling stage we anticipate that we will be able to fly in around 10 knots true.”

The Eagle Class 53’s roots lie firmly with the foiling America’s Cup catamarans. Even in displacement mode she’s an exhilarating ride. The goal is to achieve fully foiling performance

It is still early days for a project that Gonzalez describes as being “crawling before walking, before running and ultimately sprinting”, once the hydrofoils are fitted.

Yet during the development process it has become clear that there are others who are interested in the 53-footer, whether it foils or not. So, while the next big goal is to work towards building a 75-80ft long distance cruiser, currently called the 8X, interest in the Eagle Class 53 has been sufficient for the company to tool up for a limited production run.

“We have created carbon tooling for the 53 and are looking to build around seven of them,” said Gonzalez. “For the 8X, we are hoping to build three with the first being available during the winter of 2021-22.”

Gonzalez is a realist when it comes to the future. “As we all know, foiling has been around for a long time in military and public transportation, so we need to set an example to insurance companies and the likes that we are foiling safely and encourage others to follow. But the time has come. This is part of the evolution of our sport.”

Specification

LOA: 16.50m (54ft 2in) LWL: 16.08m (52ft 9in) Beam: 8.50m (27ft 11in) Draught: 0.41m-3.05m (1ft 4in-10ft 0in) Displacement (light ship): 6,000kg (13,228lb) Displacement (max load): 7,540kg (16,623lb)