“It’s what the kids want to be doing,” says the America’s Cup skipper, wearing the Red Bull cap of his sponsor, a brand that promotes extreme sports. “These boats are awesome to sail,” says the skipper’s mate, pleased about the platform now used in the America’s Cup.

It’s foiling, and it’s all the rage.

Sailing has incurred progressive steps in equipment, from sails to cordage to spar and hull construction. The advancement of canting keels was significant, but foiling is the most transformative step I’ve seen in my lifetime. When a boat is fully foiling, it enters a different dimension. It is flying.

While hydrofoil technology is nothing new, it was Rohan Veal’s persistence to apply the practice to the International Moth, as well as volumes of video he shared online, that elevated foiling to the current conversation. When Veal became the first to win a Moth world championship with foils in 2005, the development class was never the same. It’s no surprise the foiling Moth was born from Australian thinking, as skiff sailing and lightweight keelboats are in their DNA, but the high-performance wave was already extending beyond their shores. Once stodgy keelboat fleets in the United States had new designs planing downwind, with upwind performance aided by “damn-the-torpedos” gut hiking.

This trend toward high-performance boats prompted another shift—toward expertise. These speedy designs require more skill to sail. Their tune and trim are twitchier, crew work needs to be sharper, and helming demands more technique. The game is becoming far more technical, resulting in the blooming industry of professional coaches and crew. More investment is being made to participate in what is meant to be a recreational pursuit. These boats may be more fun to sail, but they are catering toward a smaller market. It’s not a template to grow the sport, and now foiling is raising the bar.

The 34th America’s Cup demonstrated how a 72-foot boat could be lifted, balancing on a few feet of carbon foils, while retaining buoy-racing maneuverability. The application of foiling appendages seemed limitless. The smart people quickly got to work, designing foiling boats to bring to market for those people eager to ride this most transformative wave. As exciting as the future looks, with the advancement of high-altitude sailing in the sport, a few truths may hamper its growth.

Foiling boats are meant to fly, but when they’re not, their low-riding mode can be agonizing. Foiling appendages present more drag than traditional daggerboards and rudders, and hull drag is, well, drag. In the Moth class, they seek to race only when there is enough wind to foil, which is at least seven knots.

Paul Bieker, whose design reputation includes International 14 hulls and who was the foil guru for Oracle Team USA, sees this wind limit as a universal obstacle. “The lift a foil can produce is proportional to speed through the water squared, so using them to support the weight of the boat really only works efficiently at higher speeds,” he says. “My take on it at this point is that an efficient foiling boat will need to achieve a speed of at least 10 knots for take-off.”

Another obstacle to foiling boats is sea-state. Multihull designer Gino Morrelli, whose company worked with Team New Zealand during the 2013 America’s Cup, sees this as the undeveloped aspect of foiling appendages. “So far, for all the proven applications, from America’s Cup boats to Moths, these boats are geared for reasonably sheltered venues,” says Morrelli. “How fast and how far foiling develops beyond the thrill-seeking, race-type boats will depend on what we can learn and develop when sailing in open-ocean conditions. Short chop, steep chop, long swell, upwind and downwind. Right now, this is where we are finding the Achilles heel of the current foiling geometries and systems.” The notable exception to this is Hydroptère, the foiling trimaran that holds the D Class (over 300 sq. ft.) world speed record of 51.36 knots. “They have demonstrated how the configuration can handle certain ocean-type sea-states, but their design also has a lot of drag when not in foil-mode, and in general not very practical for general use,” observes Morrelli. “There will need to be superior solutions for us to fully overcome this roadblock. But I am hopeful. Right now, we are all just like the Wright Brothers; we are just learning how to fly.”

To what degree it can be overcome will be the question, as modern dinghies are already challenged when waves exceed their tolerance. During the 2008 Olympics, strong but sailable conditions for the final 49er skiff race saw the fleet of elite athletes scrambling to stay upright, with most failing. For the 2016 Olympics, the sailing venue includes an offshore course, but with the large swell that can develop, only the older classes like the Finn and 470 may have the seaworthiness to survive it. The newer classes like the skiffs and Nacra 17 require sheltered waters. Performance progress comes with a price.

Bieker is hopeful the sea-state conundrum can be overcome, but so far, foils that are more stable also have more drag. “It is a difficult thing to model, and for sure the ability to handle a sea state will have performance cost. The AC72s hated even the slightest groundswell at some angles.”

Much like air travel, there is also a financial cost to flying. Expensive materials are needed to build light hulls, the long, thin foils are complicated to build with the strength and structural integrity required, and foil-control systems are complex. The current foiling options include the Moth at $25,000, the Flying Phantom at $40,000, the Nacra 20C FCS at $55,000, the $450,000 GC32, or the 40-foot Gunboat G4 at $950,000. An entry-level foiling conversion for a Laser with Glide Free Foils costs roughly $4,000. For kiteboarders, foilboard packages start at $2,000.

While most of the marketable foiling boats are one-design, the day will come when boats with foiling appendages will seek to compete in handicap events. Not every foiling solution lifts the hull clear of the water; some are designed to reduce hull drag only. The transition for them to participate will not be smooth. Fair ratings are already a challenge as boats of various performance types gather. Increasing speed, particularly when that speed greatly varies amid windspeed and sea state, will heighten the task.

I think back to the growth of windsurfing, when smart people pushed the boundaries, developing boards and sails and masts that created more speed and excitement. But it also raised the skill and wind-strength required, limiting who and when one could sail. With boardsailing fully focused on the high-performance range, classes that were suitable for light winds and less skilled people were forgotten and soon faded away.

The growth of foiling will continue, but what is special now should not be forgotten by the excitement of this new development. “What matters most is not what kind of boat you are sailing…just that you are sailing,” counsels Ben Hall, who sails everything from A Class Cats to his Evelyn 32. “Being on the water, and enjoying the camaraderie of like-minded people, is what fuels our sport.”

We should consider the history of windsurfing as a guide: when we cater to the minority we risk losing the majority. It’s an important standard to remember.

@http://www.sailingworld.com/