The hydrofoil concept is simple: put an aeroplane wing on the underside of a boat, so that as the boat sails or motors forward, it rises. As the boat rises, there will be less hull surface touching the water, meaning less drag and displacement, yielding more efficiency.
For almost as long as aeroplanes have existed, there have been historic attempts to make a boat “fly” through or over the water using hydrofoils.
“Foiling has been around for a long time – it is nothing new. The tools and the understanding of foiling have grown and now led to this current explosion of foiling,” says Simon Schofield, co-founder and chief technology officer of Ben Ainslie Racing Technologies. “It’s a combination of the computer simulation technology, the manufacturing techniques, the design, materials and the control systems, plus machine learning to make it all work.”
There is also the joy of intoxicating speed. “Dinghy sailing is changing rapidly,” says Mark Evans, General Manager of McConaghy Boats, an Australian brand name with a busy shipyard in Zhuhai. “Youth will not want to go slow in sailing.”
Evans reckons that as more kids start their sailing careers on foiling boats, like the foiling Moths that McConaghy’s has been building for years, they will not want to sit in a monohull dragging through the water. Foiling Moths – dinghies that fly completely out of the water – are most popular in Europe and the US. In Asia, only Japan has a small foiling moth association.
But that mood may shift.
In the 2010 America’s Cup, competitors Larry Ellison and Bertarelli went head-to-head in massive 90-foot multihulls, achieving incredible speeds. Their competition broke the mould of the America’s Cup racing, likely forever.
The 2013 and 2017 editions were fought in hydrofoiling catamarans, with each iteration of the race seeing updates to the design and the foils. This year’s America’s Cup is being contested in monohulls that deploy enormous hydrofoils and fly completely out of the water.
One of the downsides of (past) America’s Cup competitions was at the end of the racing cycle, when the teams dispersed to the winds. It was a great shame because all the tech and knowledge dissipated – John Cooper, CEO of BAR Technologies
The move to hydrofoiling yachts has also changed the America’s Cup image into something that more resembles F1 motorsport, with the focus on technology and computing power.
The speeds now achieved by America’s Cup yachts are remarkable and turning heads. But will hydrofoiling make it to the larger yacht market?
BAR Technology was co-founded in 2017 by Martin Whitmarsh and Simon Schofield, both America’s Cup veterans, to take the know-how earned during the rigorous campaigning for the cup and try to apply it to the yacht and commercial boat market. Whitmarsh, chairman of BAR Technologies, is an aerospace engineer by training and brings long experience as McLaren Group CEO to the table.
“One of the downsides of (past) America’s Cup competitions was at the end of the racing cycle, when the teams dispersed to the winds. It was a great shame because all the tech and knowledge dissipated,” says John Cooper, CEO of BAR Technologies. Sir Ben Ainslie remains a major shareholder in the company.
Much of BAR Technology’s current work is the commercial boating sector. A major project is applying foils to all-electric catamarans to create a highly efficient, non-polluting boat to service the world’s growing array of offshore wind turbines. Schofield thinks that it will be a combination of hydrofoiling and electric power that ultimately yields an emissions-free yacht.
Making a light, high-performance yacht fly on foils is much easier if you don’t have to worry about crew and guest comfort
The biggest foiling foray into yachting came down to a personal relationship between Whitmarsh and Princess Yachts Executive Chairman Antony Sheriff, who spent several years as CEO of McLaren Automotive.
Kiran Haslam, chief marketing officer for Princess Yachts, said he wanted to develop a sexy new, entry-level yacht for Princess Yachts in 2015 and found board-level resistance at the time. Then Antony Sheriff joined. “Antony is never afraid to try new stuff – he likes to experiment. He likes Monty Python. And he liked the R35 concept,” Haslam said.
According to Haslam, Sheriff then got Martin Whitmarsh on the phone about doing a sexy new boat for Princess, and Whitmarsh suggested foiling technology. “Some of the stuff they (BAR Technology) were doing was beautiful. They had developed and mapped out stuff that was incredible,” Haslam said. “Antony doesn’t sit still; he wanted something that was radically different.”
When it was launched, the Princess R35 might have been the most advanced motoryacht application of foiling yet. The foil can be retracted up to the hull. When deployed, onboard sensors are feeding information about the boat’s performance into an onboard computer that then makes minute adjustments to the foil trim at up to 1,000 times per second, in order to optimise performance.
An owner would never come to us saying ‘I want a hydrofoiling boat’. It’s always just a solution to another question – Perry Van Oossanen
The technology borrowed from America’s Cup technology, which used onboard computers to monitor the performance of foils and “suggest” adjustments to the crew.
The foils on the R35 were placed at the rear of the boat and provided what is termed “foil assist”, meaning that the boat’s hull does not leave the water completely. In fact, the foils are as much about stabilising the yacht when underway as providing lift.
In the end, only a very small number of R35s were produced. Sheriff says that another foiling yacht is not in the works yet. “When we did the R35, we were about eight years ahead of the curve,” says Haslam, comparing it to companies that came out with all-electric cars before they became the trend.
Wajer Yachts, the Dutch brand of superyacht tenders and sports boats, relaunched its 38-footer with a static foil assist, provided by Van Ossanen Naval Architects. Wajer claims that the foil, placed amidships and not deeper than the pod drives, reduces fuel consumption by up to 20% while speed increases by three to six per cent at the same power.
But the challenges are not over. Making a light, high-performance yacht fly on foils is much easier if you don’t have to worry about crew and guest comfort. To make foils practical and economical in production boats for a mass-market more focused on leisure is harder, particularly if onboard space is a key focus.
Beneteau Group experimented with a foiling production sailboat in its Figaro 3, which was introduced as a one-design racer for the Figaro race, a solo offshore race in France favoured by Vendee Globe winners and aspirants.
“Foils definitely have a turbo effect on any boat, but they take a lot of space inside and require systems that are not easy to install or maintain,” says Luc Joëssel, product manager of Beneteau Group, explaining the challenges of making such a boat for the mass market. “Foils are expensive and reduce the comfort (in terms of space), just the opposite of what a recreational sailor is looking for.”
Foils definitely have a turbo effect on any boat, but they take a lot of space inside are not easy to install or maintain – Luc Joëssel of Beneteau Group
Joëssel says that Beneteau Group currently has no plans to add foils to any other yachts in its range.
Beneteau Group had planned to build a 10-metre powerboat with a foiling system, according to Seair President Richard Forest, but the project was halted with the arrival of new management. Seair was founded in 2016 to research foiling technology and systems and sell that knowledge on to production sail and motoryacht brands.
Forest says that acceptance for foiling systems in the production boat market is just not there yet, in part due to price, recalling a meeting with Beneteau’s top management. “The target for powerboats is to have the price of a foiling boat not exceed 20% of the normal price. When we reach this target, the market will become more accepting.”
Seair has begun to focus on building its own range of foiling RIBs and sailboats, mostly for ultra-wealthy tech enthusiasts, and for the military.
While small and medium-sized yachts may struggle with hydrofoils in the near future, there might be more uptick among the superyacht set, where their sizes are bigger and there’s more space for customization and therefore, experimentation.
To create a one-off foiling design for Finland’s Baltic Yachts, BAR Technologies designed and built an eight-metre, single foil that would slide under the owner’s cabin amidships, extending out on either side to make extra righting moment. This was fitted to the 43-metre sailing superyacht Canova, which was launched in 2019 and won several awards.
Schofield said the challenges of engineering the foil for Canova were immense, including finding ways to get a single hydrofoil to slide back and forth without any protrusions, to bear the immense weight and pressure of the foil and to do it while keeping the space for the master cabin undisturbed.
One of the biggest players in the market for adding foils to superyachts is Van Oossanen, the Dutch naval architecture team that has worked extensively with Heesen superyachts. Van Oossanen has patented the hull vane, a foiling system that goes at the aft end of the boat, providing lift that amounts to a specialised trim system, rather than lifting the boat out of the water.
“If you make the boat full aluminium or carbon – very lightweight with a very low standard interior – and you’re not too worried about noise and vibrations, then you can get away with it. But for your typical high luxury high-end European motor yacht or, or cruising sailing yacht, fully foiling is not really a solution,” says van Oossanen.
Van Oossanen has created a new company, Hull Vane, which markets its foil-assist and hull vane solutions to shipyards and ship owners. Perry van Oossanen says that he and his company have been working on hydrofoil technology for larger, heavier vessels for nearly 20 years. They claim that efficiency of the hull is boosted by around 15 to 20%, depending on the boat, while reducing slamming in waves and uncomfortable vertical motions. Van Oossanen says that his patented Hull Vane has now been used on 45 different projects, though conversations with owners don’t normally begin with hydrofoil technology.
“We basically supply the Hull Vane and the Foil Assist products to our clients, but an owner would never come to us saying ‘I want a hydrofoiling boat’”, Van Oossanen says. “It’s always just a solution to another question. Basically, I want to do this speed with this power, or I want to have super fuel economy, for example, and then we usually resort to foils in that case.”
Though Van Oossanen are in the lead in researching and monetising hydrofoil technology, they are no longer alone.
Legendary naval architect Philippe Briand says that he began experimenting with hydrofoils in the 1980s, penning the design for a cruising catamaran assisted by foils and powered by a kite sail. Briand says the technology in materials and computing power now make hydrofoils a reality, it is the traditional nature of the superyacht market that inhibits further acceptance. Brokers and dealers may not be comfortable selling technology that are not familiar with, in Briand’s telling, adding that it took 20 years for fin stabilisers to become commonplace in the market.
Briand says he is now working on a 70-foot catamaran project that will include a foiling system.
McConaghy Boats is also building a new series of 60-foot-plus motor catamarans that have a foiling system attached between the hulls. The first one in production is for Grant Dalton, a world-renowned competitive sailor and CEO of America’s Cup titleholders Emirates Team New Zealand.
McConaghy’s Mark Evans told Asia-Pacific Boating that he will soon launch a new foiling sailboat that’s designed for an older, perhaps slightly out of shape sailor, to get into a pod and simply start foiling. His inspiration was the extreme speeds that ice boaters can reach in their pod-like structures.
For now, foiling in yachts remains an outlier. But growing pressure on the yachting industry to comply with fuel efficiency and emissions reduction may make the timeline to full adoption shorter than previous technologies. And of course, among all the young sailors flying around on foiling Moths, there will be future yacht owners.
Next page: To the foils, the spoils: A brief history of foiling