The Engineering and Design Behind Modern Racing Yachts

The "America's Cup" is the world's oldest trophy in international sports.
Christopher McFadden

The "America's Cup" is the Formula One of the yachting world. The oldest and longest-running competitive yacht race in the world, the yachts of today could not be any more different from their early forerunners. 

As you are about to find out, the competition has pushed the boundaries of boat design to the limits, and modern racing yachts are some quite impressive, and complex pieces of engineering.  

What is the "America's Cup" boat race?

In 1851, a schooner called America won a novel sailing race around the Isle of Wight, England, against a fleet of British yachts. For this achievement, it was awarded a "100 Guinea Cup" trophy.

Also known as the "Auld Mug", this sailing race is widely considered one of the hardest yacht races to win. It is also the world's oldest yacht race. It is one of the longest-running, international sporting competitions, preceding the modern Olympics by 45 years, and the FA and Ryder Cups. 

In honor of the prestigious achievement, the cup was renamed the "America's Cup" to honor the winning schooner and her crew. The trophy was then donated to the winning yacht club, The New York Yacht Club (NYYC) under the terms of "The Deed of Gift".

americas cup trophy
The "Americas Cup". Source: America's Cup

Funnily enough, or frustratingly so (depending on your point of view), despite the inaugural race being hosted by the UK, the cup has never been held by a British team. 

The deed stipulates that the cup must be made available for perpetual international competition. The deed also sets out requirements for any other yacht club to challenge the current holder, and if they win, they gain stewardship of it — until successfully challenged, of course. 

Not only that, but the winning team also gets to set the rules for future races and the races' location. Unfair perhaps, but it has certainly driven innovation throughout the years (more on that later). 

The first challenge of the cup occurred in 1870, and races have been held 35 times since. 

The NYYC held the trophy between 1857 and 1983 when the Royal Perth Yacht Club, represented by the yacht Australia II, comprehensively won the race. NYYC remains the longest defending team record of the cup to date. 

When a challenge is raised, the race takes place between two yachts, one of which is known as "The Defender". This yacht represents the yacht club that currently holds the cup.

america cup challenge 2007

Image from "America's Cup" second race held in 2015. Source: Steven Vacher/Flickr

The other, known as the "The Challenger" represents the competing yacht club. 

Since that day, the race has inspired yacht designers and crews to push the limits of their craft for ever more impressive performances. It has become the most prestigious and highly prized sailing trophy around the world and is a true test of sailing skill and of boat and sail design. 

Competing in the race is extremely expensive, and modern teams can spend upwards of $100 million each. The 2013 winner spent roughly $300 million all-in on their entry, for example.

Previously only one challenging team could compete to win the cup, but since 1970, multiple challenging yacht clubs may compete in qualification rounds with each other until an outright winner is found. The winning team can then challenge the defending yacht club one-on-one.  

The cup is currently in possession of the Royal New Zealand Yacht Squadron, specifically Emirates Team New Zealand, who won the cup in 2017 and will attempt to defend the title in the 36th defense of the cup that will take place between 6th to 21st March 2021 in Auckland, New Zealand. They will need to defend their title against the Italian crew Luna Rossa Prada Pirelli Team who recently beat the British finalists, INEOS TEAM UK during the qualification finals. 

americas cup defender america
The 1992 defending yacht America. Source: Dale Frost/Wikimedia Commons

What kind of yachts can be used in "America's Cup"?

Historically, races were held between yachts of between 65 to 90 feet (20 and 27 meters)  in length along the waterline. This convention would ultimately culminate in the so-called J-class yachts (regatta) of the 1930s. 

World War II led to a hiatus of races for almost two decades, which resulted in the NYYC making changes to the "Deed of Gift" to allow smaller, less expensive yachts to compete. In 1990, a more formal standard, called the "International America's Cup Class" was introduced and used until 2007.

These rules were legally challenged in 2010 to allow 90 feet long (27 mt) waterline multi-hull yachts for the first time. This ultimately led to the 2013 America's Cup race between two AC72's, the Oracle Team USA's catamaran powered by a towering wingsail and Emirates Team New Zealand, which introduced foiling (wing-like foils mounted under the hull to provide lift).  

The current rules, AC75, have been agreed upon between the current champions and their challengers, Luna Rossa. These rules set out the allowed parameters of yacht design that are deemed eligible for the race.

americas cup 2012 lunna rossa
Source: Ciorra Photography/Flickr

The rules are to ensure a fair and exciting race, but also allow enough wiggle-room for designers to be creative with their designs. 

Without getting into the weeds, the main takeaways from the AC75 rules are (courtesy of "America's Cup" official site): 

  • Strict limitations on the number of components that can be built including hulls, masts, rudders, foils, and sails, thus encouraging teams to do more R&D in simulation and subsequently less physical construction and testing
  • Supplied foil arms and cant system to save design time and construction costs
  • Supplied rigging
  • One design mast tube

The main change from previous recent races is the move away from catamarans to monohull yachts with huge hydrofoils. 

In addition, the ‘soft wing’ mainsail concept that has been developed for the AC75 Class Rule is expected to have a trickle-down effect on sailing in the future.

americas cup ac75
Main design elements of an entry yacht under AC75. Source: The "America's Cup"

“The AC75 Class Rule sets the parameters for the teams to develop and race the fastest sailing monohull on earth. The rules are the result of close collaboration and a true partnership between Emirates Team New Zealand and Luna Rossa,” said Martin Fischer, Design Coordinator for Luna Rossa Challenge.

"America's Cup" yachts are like nothing else on the water

Being the most prestigious sailing race in the world, the race attracts the very best in engineering and skill the sailing industry has to offer. Previous years have pushed the technology of the sailboat to ever-extreme limits, and the 2021 race is no exception.

Under the current AC75 rules, teams have designed their boats to be even faster, and more complex, than ever before. Take the British INEOS entry for this year.

The team's two yachts, Britannia and Britannia 1, are both 74 ft (22.8 mt) long at the waterline and have been designed to cut through the water on massive hydrofoils that allow them to achieve speeds of 46 knots (85 km/h). These yachts are huge in comparison to recent races — especially those used during the 2017 cup. 

americas cup britannia
The Britannia. Source: INEOS

Each British vessel took around 46,000 hours to build, 90,000 hours to design, 75- to 100 thousand hours to CNC machine, and weighs around 6,450 tonnes. The yachts also include 17,300 individual parts, 140 sensors, and 787 ft (240 mt) of hydraulic pipes, and are sailed by an 11-person crew.

Interestingly, the hulls of these yachts are more akin to aircraft than traditional yachts. This is because, as they ride on hydrofoils, they spend most of the time out of the water. 

The hydrofoils themselves also borrow from aircraft design and, as stipulated by the rules, they must use flaps or elevator-type elements along the foils to control the boat. All well and good, but water is around 800 times denser than air, creating some real engineering headaches to overcome. 

Design and construction times have also been pretty tight for the current race. The rules were only formalized in 2018.

To speed up design and build, competitors in the current America's Cup have turned to multiphysics computer-aided design software to rapidly prototype and test performance virtually. This is a technique that is also pretty much standard practice in Formula One racing today.

Another major innovation from the "America's Cup", is that it gave a boost to the development of a novel form of engineering — mechatronics. The strict rules of AC75, and the requirement for big-hydrofoil monohulls, require the vessels to have very precise controls and other elaborate systems for "takeoff" and "flight" just above the water's surface. 

americas cup ac75 yacht
Example of an AC75-standard yacht. Source: The "America's Cup"

These design considerations have required the skills of a new kind of engineer, a mechatronics engineer, to critically assess and consider the micro to macro elements of yacht design. mechatronics engineer integrates software design, hardware design, electronics, and mechanics to create simpler, more economical, and reliable systems and to ensure smooth, and reliable interaction through an intricate system design.

Such is the required performance of yachts in the race today, that teams can win or lose based on how these systems are integrated and perform. Even a few seconds of delay can be enough to lose a race. 

The level of technological innovation and team skill required to design and build the yachts and win "America's" Cup" is very impressive indeed. Today the yacht design process could not be more different from when the race began and has more in common with aircraft design than ever before. 

The 2021 race is shaping up to be an exciting one, and it will be interesting to see if New Zealand can retain its title. 

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