34th America’s Cup: New AC72 class, the fast, spectacular, wingsail catamaran unveiled
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Written by Chelsea Smith
Encapsulating the 34th America’s Cup – the best sailors in the world on the fastest boats – the AC72 will be a physically demanding boat capable of top speeds twice the windspeed.
The new AC72 class is the first-ever wingsail catamaran class for the America’s Cup and the fastest-ever class in the iconic 159-year-old competition. It replaces the ACC monohull class, which was created in 1988 and first raced in 1992 Cup.
The new AC72 catamaran which will be used in the 34th America's Cup. Credit - 34th America's Cup
The new AC72 class catamarans will make their racing debut in the 2012 season for the America’s Cup World Series ahead of the 34th Match in 2013.
A catamaran was selected as one element to transform and enliven the America’s Cup for the future. A multihull is the ideal dynamic class, capable of being raced hard in winds from 5 to 30 knots to minimize racing delays due to winds too light or too strong.
AC72 design parameters:
LOA 22.0 meters (72 feet) Beam 14.0 meters (46 feet) Displacement 5,700 kilograms (12,500 pounds) All-up weight 7,000 kilograms (15,500 pounds) Wingsail area 260 square meters (2,800 square feet) Wingsail height 40 meters (130 feet) Wingsail chord 8.5 meters (28 feet) Sail trimming Manual grinders Configuration Twin-hulled catamaran Crew 11 Sail trimming No mechanically powered systems Sail area reduction Removable top sections/leech elements Appendages Maximum of 2 rudders, 2 daggerboards Construction Minimum 600 grams per square meter outer-skin; High-modulus carbon-fiber permitted in wingsail spar
The AC72 Class Rule was drafted by a distinguished group of consultants, chaired by Pete Melvin, on behalf of US SAILING.
Melvin, formerly a designer of aircraft for the McDonnell Douglas Corp. is a champion multihull sailor, having twice won the A Class Catamaran World Championship. Morrelli & Melvin Design & Engineering, Inc., also designed the record-setting maxi catamaran PlayStation.
Organizers of the 34th America’s Cup believed it was essential that the first new class of boat to be introduced since 1992 should be developed independent of any of the teams competing. A Concept Brief was published in June setting out the performance and operational requirements.
The AC72 is a “box rule.” This narrows down the design parameters so that while teams have freedom to create their own boats, they will be similar in dimensions in order to ensure close racing.
Hulls and beams will have to be assembled in two days and disassembled in one to allow America’s Cup teams to move efficiently between venues. Replaceable “crumple zone” bow and stern cones will allow for quick repair in the in the cut-and-thrust of racing.
To fast-track all teams to a common level of technology, a new, smaller class of identical wingsail catamaran, the AC45, will be used for the 2011 ACWS season while teams create their new high-performance catamaran.
To ensure the fairest possible competition for the 34th America’s Cup, the draft of the AC72 rule is being made available to teams for feedback before it is finalized. A similar process was used to create the Protocol for the 34th America’s Cup.
Not only does this give all teams a voice in the rule creation process, but they will have all competition rules finalized before entering the competition – another first in the America’s Cup.
Once finalized, the AC72 Class Rule will be administered by the newly created independent organization, America’s Cup Race Management.
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Featured Stories | August 26, 2013
Inside the fastest boats in america’s cup history with mit meche.
By Genevieve Wanucha
“….It’s a clean start!” the America’s Cup commentator shouted yesterday . “And the Kiwis take the lead!” Two sailboats blasted through a foggy San Francisco Bay, dueling for a chance to race against the defending champion Oracle Team USA. Minutes later, Emirates Team New Zealand sailed to victory past Italy’s Luna Rossa Challenge, and now wait to confront their formidable rival in the finals on September 7.
The America’s Cup is the world’s oldest sporting trophy, backed by 162 years of sailing tradition. This year’s motto hints of something new: ‘Best Sailors. Fastest Boats.’ After winning the last cup in Valencia, Spain, in 2010, Larry Ellison, the billionaire entrepreneur and the owner of Oracle Team USA, pushed to reinvent the competition into a spectacular television-friendly event. He got his way—big time. The 2013 America’s Cup is now taking place much closer to the shore, within view of cheering spectators, music concerts, and grandstands. The biggest change is the newfangled boat design.
The new yacht, called the AC72 (America’s Cup 72 class), is unlike any sailboat that’s ever raced in an America’s Cup. The 72-foot-long, wing-sailed catamaran can travel more than twice as fast as the boats that competed in 2010. When the slick carbon-fiber crafts really get going, both hulls levitate out of the water and begin to fly over the surface on retractable underwater appendages called hydrofoils. The decrease in drag during foiling mode can boost the yacht’s speed past 45 knots, or 52 miles per hour. “It’s surreal,” says Team New Zealand’s wing trimmer Glenn Ashby.
Several professors in MIT’s Department of Mechanical Engineering , experts in naval architecture, marine hydrodynamics, and fluid mechanics, know a thing or two about sailboat design. Some have led the design of past U.S. America’s Cup boats. And they say that these AC72s have sailed straight into a new frontier in advanced marine technology. So, Oceans at MIT invited professors Doug Hart , Paul Sclavounos , and Jerome Milgram to answer a few questions about the fastest yachts in America’s Cup history. Knowing what they know will change the way you watch the race.
What makes the AC72 catamarans so fast and unique?
“In order to counter the side force generated by the sails, boats must have a wing shape below the water that generates a force in the opposite direction. Catamarans use long thin rudders and hydrofoils near the center of the hull called daggerboards. The AC72’s are unique in that they have rudders and daggerboards designed to push up on the hulls and lift them out of the water while, at the same time, countering the sideways force of the sails.
In addition, AC72s use “wing” sails rather than the typical canvas sails you see on most sailboats. These are structures built very much like the wings of an airplane. They are “monocoque”-type structures, which means that part of the load is carried by the outer skin. This support allows the sails to be very thin and ridged. This design provides a means of controlling and optimizing the shape of the sails in ways that traditional canvas sails can not be controlled or optimized.
Finally, as with all catamarans, the hulls are long and thin. The force on the sails acting to flip the boat is countered by the weight of the crew and the weight of the part of the boat that is upwind of the sail. The two hulls of catamarans can be separated by considerable distances providing significant leverage against flipping. The long thin hulls also generate little wave drag (drag caused by the generation of waves by the boat itself) and help to pierce oncoming ocean waves rather than slamming into them and decelerating the boat.”
Designing innovative yachts must involve a great amount of fluid mechanics or marine hydrodynamics. What specific research areas are critical for this kind of sailboat design?
Paul Sclavounos, MIT PhD ’81, Professor of Mechanical Engineering and Naval Architecture. Interests: Marine Hydrodynamics, Marine & Mechanical Engineering. Professor Sclavounos has been a design contributor to three America’s Cup syndicates.
“The design of the new AC72 boats is a complex process lying at the intersection of a number of disciplines; marine hydrodynamics, aerodynamics, structural mechanics, advanced composites, and optimization theory. Of these disciplines the ones that are critical for the design of AC72 boats are marine hydrodynamics, aerodynamics and carbon fiber composites. The fluid dynamics involved in the design of the AC72 boat may now he handled reliably by computer programs that solve the Reynolds Averaged Navier Stokes Equations reducing the need for extensive tank and wind tunnel testing.”
Jerome Milgram , MIT PhD ’65, Professor of Mechanical and Ocean Engineering, William I. Koch Professor of Marine Technology, Emeritus. Professor Milgram has been a design contributor to more than eight America’s Cup syndicates.
“For the hydrofoil boats, called foilers, the fluid mechanics of lift is paramount. It differs from the lift of airplanes in that there is a free surface (water) very close to the foils, whereas an airplane lifts in nearly an infinite fluid (air). Lift in the presence of a free surface is the new field of fluid mechanics for foiling boats. In an ordinary boat, there is lift in the form of side force generated to counterbalance the side force of the sails. However, most of the lifting surface of an ordinary sailboat (the downward-projecting centerboard ) is further from the free surface than is the case with a foiler, on which most of the underwater appendage is horizontal and close to the free surface. (See this video: Hydrofoils: Flying on Water )
The new AC boats have rigid wings instead of fabric sails. Their elliptical leading edges can have a suction force on them, which cancels out much of the drag. Thus, the drag coefficient of a rigid wing can be much lower than the drag coefficient of a sail. Furthermore, rigid wings can withstand small areas of pressure difference reversal that would cause an ordinary sail to luff, or flap. This increases in the amount of available control of the lift distribution.”
“Sailing yacht design is extremely complex. Sailboats are anything but simple – generally far more complex then airplanes. They are a balance of compromises between rules governing their construction, structural properties of the materials they are made from, wind and water forces, crew safety, and the controls needed to operate them. While a tremendous amount of modern technology and numerical modeling goes into the designs of these yachts, much of their design is based on practical experience, experimentation, and trial and error. Sailboat races are often won by fractions of a percent difference in overall speed. These differences can be the result of the ability to out maneuver the other boat, point slightly higher into the wind or any number of other factors. Such tiny differences are very difficult to account for by simple numerical modeling thus, yacht design is still very much an art.”
Are there any downsides to this AC design?
Jerome Milgram:
The interaction of a high speed boat with waves is different than the wave interaction of an ordinary low speed boat. When an AC boat traveling at high speeds has its bow hit a wave, the wave can cause an instantaneous increase in drag, slowing the boat with the air wing force and the inertial force of the boat slowing down can cause the boat to pitch pole. Unfortunately, there has been one death due to this kind of inertial and hydrodynamic interaction between the boat and sea waves.
There is some criticism of this departure from tradition and of the increased danger associated with the new design. But, others are excited to see this as more of a spectator sport and demonstration of futuristic technology. What is your personal reaction to this sea change in the America’s Cup?
Paul Sclavounos:
“There is a long and illustrious history of Americas’ Cup mono-hull yachts and many are nostalgic of this tradition. The innovations introduced under the IACC rule have led to outstanding boats that had almost exhausted every corner of the rule, leading to margins of victory often less than a minute for a three-hour race. The new Americas’ Cup rule represents an evolution that is, in a sense, a consequence of the maturity of the designs developed under the previous rule.
The design of the AC72 yachts draws upon advanced marine technologies, e.g. computational fluid dynamics and advanced composites, increasingly used for the design of other marine structures, e.g. fuel-efficient ships, composite mooring systems for offshore platforms and multi-megawatt offshore wind turbines. As has been the case in the past, the races of new AC72 boats will be exciting, and they stand to raise an awareness of the importance of technology in the design of advanced marine vehicles. As to the dangers associated with the new design, it is a risk that is hopefully small yet to a certain degree inevitable given that a new frontier in yachting is being explored.”
“I see both sides of this issue and each has merit. The boats do depart from tradition and are certainly dangerous, but they have the thrill of very high speed. I would not personally get on one of these boats. I have too much sense for that. Others see it differently.”
“While safety is certainly a major concern, as an engineer, I find these new yacht designs extremely exciting. My own feeling is that the America’s Cup races became too bogged down in rules and lost sight of what made them exciting. I hope these new yachts spark people’s imagination and usher in a new generation of young sailing enthusiasts.”
Published on August 27th, 2013 | by Editor
America’s Cup: What you may not know about the AC72
Published on August 27th, 2013 by Editor -->
By John Longley, 1983 America’s Cup winner After spending a week in San Francisco and having the opportunity to talk to a number of people who have actually sailed the extraordinary AC72s, I have gathered a bit of AC72 trivia to share…
* If you had an engine to power the hydraulics rather than grinders, you could sail the AC72s with 4 people rather than the crew of 11 they now sail with.
* There is really only one trimmer on board and he controls the wing. The helmsman controls the cant and rake of the board with buttons on a control pad in front of him but only has 3 seconds of stored power before he has to “throw bananas” into the grinding pit i.e. ask for more hydraulic power.
* They have seen 47 knots as the top speed so far but expect to see the 50 knot barrier broken in the Cup match.
* The boats go directly downwind 1.8 times faster than the wind. So if you let a balloon go as you went around the top mark you would easily beat it to the bottom mark.
* There is only 4 degrees difference to the apparent wind from going on the wind to running as deep as you can.
* If you lost the hydraulics while the boats were foiling they would be completely uncontrollable and would most likely capsize.
* It is faster to find the strongest adverse current going downwind because the stronger apparent that is then generated translates into more speed than if you were sailing in slack water. (Warning – this takes a bit to get your head around)
* When sailing downwind you look for the puffs in front of you not behind you.
* It is actually quite dry on the boats, unless you make a mistake and come off the foils, as you are flying a couple of metres above the water. Waves have almost no impact on the boat when foiling.
* In strong wind you carry negative camber at the top of the wing to “reef” or de-power the wing.
* All crew carry personal tackle so they can effectively rappel down the netting if the boat capsizes.
* Gennakers are only used below about 8 knots; the jibs only provide about 3% of the lift up wind.
* The foil on the rudder generates about 800 kg of lift with the rest coming from the center board foil to lift the 7 ton yachts clear of the water.
* The centre board foil’s tip comes out of the water so it effectively works like a governor on an engine i.e. as the board generates too much vertical lift it comes out of the water, the area is thus reduced so it goes back down etc until it finds equilibrium.
Tags: AC72 , America's Cup , John Longley
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Speed and Innovation in The America’s Cup
Get swept away in this awe-inspiring exhibit featuring the world's oldest international sporting competition.
About the exhibit:
Have you ever wanted to see a boat that can fly?
The America’s Cup isn’t just any run-of-the-mill yacht racing competition. Dating back to 1851, The America’s Cup has been the premier sailing event where the world’s top sailing teams battle it out on the water – putting their teamwork, athleticism, and engineering mettle to the test. In this exhibit, you can hear the story of one of the most notable moments in the history of the sport — Oracle Team USA’s victory in 2013 — an event dubbed “the greatest comeback in sports history!”
Not only will you get the chance to hear this phenomenal story, you’ll also see the actual 72-foot catamaran that Team Oracle sailed to victory during that fateful race. Come witness the story, and find out what made these boats “fly” out of the water at speeds up to three times faster than the wind!
What to expect:
- Test your might and see if you have the endurance needed to be a member of an AC72 sailing crew.
- Get up close and personal with the AC72 that won the 2013 America’s Cup race, which is also the largest boat in our Collection.
- Watch boats “fly” – and learn how they do it.
- Touch sample materials from these engineering marvels, like carbon fiber and Clysar film.
- Walk on the same kind of netting that the crew members did.
Discover the objects related to this exhibit through our online catalog.
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Meet the AC72
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- Updated: September 5, 2012
America’s Cup 72: Oracle Team USA
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America's Cup 2013: Oracle Team USA Optimizing Oracle Multihull Designs
2013 America's Cup Links: Basic Facts | Defender & Challengers | Schedule | Rules | The Boats: AC72 and AC45 | San Francisco
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| . Here Andrew explains how these advanced methods were adapted to the creation of large, foiling, wing-sail multihulls for the America's Cup; the thinking behind critical design decisions; and how this effort literally shaped the defending yachts:
Q: How did you get involved with the Oracle team and what role did you play in the design of Oracle’s AC72’s? I had worked with both Manolo Ruiz de Elvira and Mike Drummond at Alinghi prior to 2007 and I approached them in early 2011 regarding the optimization of Oracle’s hull designs. As a result of their support for the project I was contracted to the Oracle Racing design team from May 2011 to August 2012 to perform optimization of the hull shapes of the two Oracle AC72s. The optimization group comprised myself, Manolo, Joseph Ozanne and Michel Kermarec. Manolo provided the parent designs and performed the computational fluid dynamics (CFD) analysis, Joseph provided the velocity prediction program (VPP) and continually refined it during the project, and Michel helped define which parameters were varied and provided a sanity check on the outputs from the optimizer. What methods did you use for optimization? These were similar to those used at Alinghi for the 2007 Cup, an evolutionary optimizer linked to a VPP and a race modeling program which ran thousands of races between each pair of designs modeled. The VPP used Neural Network-based regression models for lift, drag, and other parameters, and these were derived from CFD results for a large number of parent design variations. The resulting models were capable of producing quite accurate lift and drag values for any design within the design space we had defined. Did the optimization project have a blank sheet of paper within the confines of the AC72 Class Rule, or were there some fundamental design decisions taken before beginning the process? By the time the optimization project commenced Manolo had already been developing AC72 hulls for several months, so we started with quite a refined parent design. From there we had to decide the limits on how far the optimizer could modify the parent design before it became impractical or risky for other reasons. These risks included undesirable or unquantifiable effects on seakeeping or maneuvering, as well as the possibility that the CFD may not accurately calculate the effect of extreme hull features. So for example, we imposed limits on minimum and maximum beam, transom immersion and longitudinal center of buoyancy position, to name a few. In the end we had about 10 hull shape parameters that we were varying, and we explored all of that 10 dimensional design space. For boat 2 we relaxed a few of the limits and locked other parameters where we were confident that we had close to optimal values. This reduced the dimensionality of the design space making the optimization process for boat 2 a little more efficient. How did you perform race modeling when for a long period the details of the racecourses were not confirmed? The courses had not been defined at the time optimization work started for boat 1, so we simply assumed a 50:50 split for upwind:downwind sailing. This was considered a reasonable assumption at the time given our expectations for the venue. By the time the courses had been defined, it was clear that the boats would be fully foiling downwind in all but light weather, and consequently we only needed to optimize for upwind performance. In this case the course design did not affect the optimization process at all.  Given the apparent wind speeds involved, was the aerodynamic performance of the platform an aspect of the optimization model, evolved genetically, too? No, we didn’t vary the platform aerodynamics or wing design during each hull design optimization phase, as this would have introduced additional variables that would have clouded the results. The hull shape optimization project took place quite late in the design process, and by this stage the major aerodynamic characteristics of the platform and wing had already been investigated in some detail. We used aero models based on the characteristics of the preferred rig and platform, so it is more accurate to say that the hulls were optimized based on the rest of the package. There has been a lot of discussion about the extent to which Oracle’s first boat was intended to foil. Can you clarify whether Oracle boat 1 was designed as a non-foiling boat? It was clear while boat 1 was being designed that some measure of foiling was possible. We were confident that the boats would not foil upwind, but whether the boats would foil some of the time or all of the time downwind was not clear. As a result, boat 1 was designed to cover a range of possible outcomes, with the hull shape being optimized for the entire speed range. By the time we got to boat 2, it was clear that the boats would be foiling most of the time downwind, and this resulted in the hull shape of boat 2 effectively being optimized for upwind work, as the hulls would seldom touch the water downwind. This means that the two hulls were effectively optimized for different speed ranges; hull 1 had to perform efficiently up to very high speeds, whereas hull 2 would only be immersed at speeds below about 25 knots.  Although superficially similar, the two hull shapes have some significant differences. Some of these differences were due to the different speed ranges and levels of immersion that the hulls were expected to encounter, while some were simply that the design team became more comfortable with relaxing limits for some design parameters that the optimizer had been exploring. Why are differences in hull shapes important at all, surely the hulls are going to be out of the water for the majority of each race? I think many people have underestimated the importance of having a fast boat in non-foiling mode – certainly if you were basing your opinions on the videos of the various teams training, you would incorrectly assume that the AC72s are airborne 95% of the time. The reality is that non-foiling performance is going to be an important factor in winning races. For the AC72, upwind speed made good (VMG) is about half of downwind VMG. Even though there are more downwind legs than upwind legs, the slower upwind speeds mean that 50% to 65% of the race time will be spent on upwind sailing in non-foiling mode. While an AC72 can foil by pulling away 10-15 degrees from its best upwind sailing angle, the increase in boat speed is not sufficient to produce better VMG. I suspect that it is the aerodynamic efficiency of the wing that makes it preferable not to foil upwind as the superior lift to drag ratio of the wing allows the boats to be fast at quite narrow true wind angles. I think that it’s quite possible that if the AC72 had been designed to use soft sails instead of a wing, the lower rig efficiency might have resulted in foiling at broader angles being the fastest mode for upwind legs.  The Oracle hull shapes are different than those chosen by ETNZ. Can you comment on the logic behind these differences? The Oracle hull shapes have clearly been optimized to be as slippery as possible upwind while having an adequate safety margin downwind. The hulls are fine, with quite rounded sections amidships and forward, while still retaining quite powerful stern sections. The optimizer was clearly happy to have the hulls contribute very little dynamic lift, preferring to use the main foil to provide this lift in the most efficient manner. The result is a hull shape that is low drag when immersed, and continues to have very low drag as the main foil generates more lift and the effective displacement of the hull reduces. This gives a design that minimizes the incremental drag as the boat lifts clear or re-enters the water in marginal foiling conditions or while maneuvering. In contrast the ETNZ hulls appear to have relatively flat sections along the length of the boat, and these will contribute some dynamic lift as the hull speed increases. However, in my view the generation of this dynamic lift is relatively inefficient and will incur a drag penalty. In particular I feel that these sections will not be as efficient when sailing upwind, particularly in fresh conditions when the main foil is generating enough lift to significantly decrease the displacement of the hull. In these conditions the flatter sections will not reduce their wetted surface area as effectively as the narrower, rounder sections of the Oracle boats, resulting in higher overall drag. As a result, it would not surprise me if the Oracle boats are superior to ETNZ upwind, particularly considering the attention that has been paid to the aerodynamics of the Oracle platforms. The combination of low hydrodynamic and aerodynamic drag should result in an advantage for Oracle on the windward legs. Could you provide a little more explanation of dynamic lift via the hull shape? A hull shape that is reasonably flat will generate some dynamic lift as the hull speed increases. This will result in the boat rising slightly until it finds a new equilibrium between its weight and the sum of its buoyant lift and its dynamic lift. If the boat is flat enough and the speed fast enough, the magnitude of the dynamic lift will allow the hull to rise up and plane across the water. Lesser amounts of lift may not produce actual planing, but may result in a significant reduction in displacement. Whether the resulting reduction in wetted surface area and wave-making resistance is greater than or less than the induced drag resulting from the generation of the dynamic lift depends on many factors. It is possible for the forward sections of the hull to generate dynamic lift, while positive curvature in the run aft may generate down-force. In this case the net lift may be negligible, but a significant trimming moment by the stern may have been generated, resulting in the hull squatting at high speed. This is undesirable, as is the opposite case of powerful stern sections generating more lift than fine bow sections, resulting in bow-down trim at speed. One of the things we were able to do during the optimization process was constrain for minimal changes in trim throughout the speed and displacement ranges. Trim changes at different speeds are undesirable in general, but for a foiling hull they can potentially change the angle of attack of the main lifting foil, so this was a useful side-effect of the optimization process.
For a hull without lifting foils, flat sections may be the best route to high performance if the boat is sufficiently light and has sufficient propulsive force. For a boat that has lifting foils, lift may be more efficiently generated by a high-aspect-ratio, immersed foil than it could by a low-aspect-ratio (i.e. long and narrow) hull surface. The optimizer appears to concur with this view, clearly favoring rounded, low-wetted-surface-area hull shapes over the flatter sections adopted by ETNZ. Some would argue that this view is contradicted by trends in classes such as the F18 and A-Class catamarans, and the International Moth. The F18 and A-Class cats have both seen a trend to wider, flatter hulls in recent years. However, this occurred prior to the successful use of efficient lifting foils. I would not be surprised if, once full foiling becomes more commonplace in these classes, a trend back to more conventional displacement-type hulls occurs. For the International Moth, certainly the class that has done the most foiling over the past 10 years, designers have favored quite flat sections throughout the length of the hull since foiling was first introduced in the class. However, it is interesting to see that some of the more recent designs, such as the British Exocet , have adopted rounded, low-lift, low-wetted-surface-area sections. The Exocet has been highly successful, filling the top 5 places at the recent European Championships and 7 of the top 10 in the U.K. Nationals. What are the limitations of the optimization approach taken for this project? All computer simulations are limited by the assumptions and simplifications they make. It is essential to validate and verify the methods used to ensure that results are accurate simulations of reality. In the case of the optimization project at Oracle we were dependent on numerical simulations at two different levels, CFD analysis of hull shapes and VPP analysis of the performance of a particular boat configuration. CFD programs for hull analysis are now quite mature systems, but a trade-off still exists between systems having high performance with questionable accuracy, versus those having excruciatingly slow performance but high accuracy. At Oracle we used a combination of CFD systems, and were comfortable with the approach adopted. Great pains were taken to carefully validate the predictions made by the optimizer using detailed CFD analysis of the optimized hull shapes. While the programming of a VPP for low-speed, displacement yachts is not a difficult problem, the design and implementation of a VPP for high-speed craft is another matter. In particular, high-speed craft may have multiple equilibria, or modes, in their performance. Determining whether a step from one mode to another is possible is not always easy.
A simple example of this is a lightweight dinghy in marginal planing conditions. The boat may be stuck in non-planing mode until a small amount of additional energy in added to the system, such as a small gust, a pump of the mainsheet or picking up a small wave. Any of these may be enough to get the boat on the plane, resulting in lower hull resistance and higher apparent wind speed that is sufficient to keep the boat planing in conditions identical to those in which it was formerly stuck in displacement mode. For high-speed foiling catamarans there may be several modes available at any given time, but determining which of those is the fastest achievable for any given wind strength and direction is a non-trivial problem. Fortunately we had access to Joseph Ozanne and his VPP, which has been developed and improved over several years, including its use in the design of USA 17 , the Oracle trimaran which won the 2010 America’s Cup. Joseph refined the VPP continuously during the optimization project, validating it initially against the performance of the AC45, both with and without lifting foils. As a result we had a great deal of confidence in its accuracy. What do you see for the future of optimization methods in yacht design, and particularly the America’s Cup? I think we have barely scratched the surface so far. One limiting factor has been the availability of accurate CFD analysis at reasonable cost. This is still an issue, but the continuous gains in the performance/price ratio of computer hardware improve this situation each year. Thanks Andrew! -- © 2013 CupInfo.com/Andrew Mason  Links of Interest : Do you want to learn more about Evolutionary Optimization in yacht design? Andrew Mason explains the principles of Evolutionary Optimization of America's Cup Class yachts in detail in this 2011 article at CupInfo, including the role the analysis played in the 2007 America's Cup, and how the techniques might be adapted to multihulls. Also included is a guide to some of the technical terms and concepts, and links to Andrew's technical writings which present the subject at a professional level. Read Article "Optimizing America's Cup Yachts with Andrew Mason: Genetic Modeling Advances America's Cup Performance" at CupInfo CupInfo Home 
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The AC72 (America's Cup 72 class) is a class of wingsail catamarans built to a box rule, which governs the construction and operation of yachts competing in the 2013 Louis Vuitton and the America's Cup races. ... The boats have been used in the 2013 Louis Vuitton Cup and the 2013 America's Cup.
Here, we take a closer look at the AC72, in an effort to demystify this amazing boat. Use the numbers on the image and compare them to the numbered design elements listed below to learn what, exactly, makes this boat fly. 1.PEDESTALS shift between pumping oil to the hydraulics and driving winches via mechanical linkages
Encapsulating the 34th America's Cup - the best sailors in the world on the fastest boats - the AC72 will be a physically demanding boat capable of top speeds twice the windspeed. The new AC72 class is the first-ever wingsail catamaran class for the America's Cup and the fastest-ever class in the iconic 159-year-old competition. It ...
The AC72: The AC72 is a 72-foot catamaran with a wingsail. These are the boats which will be used in the 34th Defense of the America's Cup in 2013, and in the challenger selection series of the Louis Vuitton Cup regatta. Yachts will be designed and built starting in 2011, launching July, 2012, for early testing, and begin racing in 2013.
The biggest change is the newfangled boat design. The new yacht, called the AC72 (America's Cup 72 class), is unlike any sailboat that's ever raced in an America's Cup. The 72-foot-long, wing-sailed catamaran can travel more than twice as fast as the boats that competed in 2010. When the slick carbon-fiber crafts really get going, both ...
The AC72 (Americas Cup 72 class) is a wing sail catamaran box rule, governing the construction and operation of the yachts to be used in the 2013 Louis Vuitt...
AC72 Guilain Grenier / Oracle Team USA. Calling the AC72 the most technologically advanced sailboat is not hyperbole. Upwind, on their slowest point of sail, the 72-foot catamarans can hit 25 ...
* The boats go directly downwind 1.8 times faster than the wind. So if you let a balloon go as you went around the top mark you would easily beat it to the bottom mark.
As the 34th America's Cup draws nearer, the development of the America's Cup 72 catamaran moves into overdrive. Emirates Team New Zealand hit the water first and fast. Dave Reed interviews ...
The ones used in the AC72 design, and with many other racing sailboats, are specially designed to provide balance to the entire sailboat while actually pushing the boat out of the water. Having the ship leave the water is beneficial for speed because drag caused by the movement on the water is replaced by drag from the much less hindering air.
Program for Australian TV to promote America's Cup participation, featuring John Bertrand, skipper of Australia II, wing keel winner of the America's Cup in 1983, and narrated clips of AC72 catamarans in 2013 by John Navas. For those who want to understand the basics of AC72 sailing, this is an excellent primer on both the basic and finer points of AC72 sailing.
In the 34th America's Cup the best sailors in the world will meet their ultimate match; the fastest boat in the world. Technology returns to the fore with the AC72 wingsail America's Cup catamaran, capable of regularly exceeding speeds of 30 knots. The AC72 will excite fans as it zips around the racecourse with one hull in the air.
The wing: AC72 Catamaran. The wingsail is bigger than the wing of a 747 jumbo jet and generates enormous force powering the boat at more than twice the windspeed. Bigger than the wing of a 747, the rigid wing sail is 130 feet (40 meters) tall and has five times the surface area of the wings that were used on the AC45s.
Sept. 9 (Bloomberg) -- As the America's Cup defender, Larry Ellison's team Oracle got to set the rules and choose the type of boat for this year's races. Bl...
Other foiling boats have stacked "ladder" foils intended to overcome the same issues. No such luck for the America's Cup teams. Keeping a boat sailing fast and true on foils like those of an AC72 is no easy matter. You want to keep the foils immersed at all times and in a San Francisco Bay wind-over-current chop, that's a real challenge.
The AC72 is a 72-foot catamaran with a wingsail. These are the boats which will be used in the 34th Defense of the America's Cup in 2013, and in the Louis Vuitton Cup regatta which selects the Challenger for the America's Cup. Yacht design and construction began in 2011, with the first launch permitted in July, 2012, for early testing, and ...
Get up close and personal with the AC72 that won the 2013 America's Cup race, which is also the largest boat in our Collection. Watch boats "fly" - and learn how they do it. Touch sample materials from these engineering marvels, like carbon fiber and Clysar film. Walk on the same kind of netting that the crew members did. our online ...
More: AC72, America's Cup, Photos, Sailboat Racing, West Coast; Advertisement More Racing; A Dynamic and Proving Day 6 of Louis Vuitton Cup America's Cup Match Racing at High Speed
While an AC72 can foil by pulling away 10-15 degrees from its best upwind sailing angle, the increase in boat speed is not sufficient to produce better VMG. I suspect that it is the aerodynamic efficiency of the wing that makes it preferable not to foil upwind as the superior lift to drag ratio of the wing allows the boats to be fast at quite ...
You could fit six AC45s in the space of an AC72. When hydrofoiling at speeds over 40 knots, the aerodynamic drag of the hulls becomes even more important than the hydrodynamics! Of course, when the boats come off the foils, the volume in the bows is crucial to preventing a pitchpole. Ergonomics. Perhaps the sleeper issue in AC72 design, deck ...
Best of the AC 72 that will compete for the Louis Vuitton Cup and the America's Cup in San Francisco in July, August and September 2013. Oracle, Luna Rosa, A...
AC72 - New Zealand fully lifted on her L-Foils and sailing on the Waitemata Harbour, Auckland, New Zealand. America's Cup - Day 1, Emirates Team NZ sailing on Leg 3 of Race 2, with the trademarked stylised Silver Fern licenced by the NZ Trade and Industry. Bob Fisher and David Schmidt raising a glass together at the 34th America's Cup.
Don't call it a revolution. The TF10, designed by Pete Melvin, the author of the AC72 rule, was created in 2018 for the express purpose of allowing a relatively average sailor to do what until recently was only possible for the world's elite—competitive racing aboard a large foiler—and what I learned on that wet afternoon on Narragansett Bay is that foiling has now broken the barrier ...