Written for Seahorse Magazine:
Predictably, the return of soft sails to the America’s Cup under the new New Zealand-led regime has sailmakers rubbing their hands – not so much for the commercial prospects as for the potential design and technology leaps that will probably ensue. Having been forced to the sidelines by the hard-wing technology of the past two Cup cycles, sailmakers are once again at the forefront of delivering the driving force for the 2021 iteration.
Richard Bouzaid, design chief at Doyle Sails, has long years of experience in America’s Cup, Whitbread and Volvo Ocean Race, Vendee Globe and other grand prix campaigns. He knows first-hand that nothing forces the game forward quite like the America’s Cup.
“It will be very interesting to see what evolves in terms of the rules around soft sails. It will undoubtedly be good for our industry as a whole. It will allow the whole game to progress and introduce new ideas.”
Early concept drawings of the radical new foiling monohull for the 36th America’s Cup have shown a double luff mainsail, which is effectively an effort to create a smooth wing-like transition from the mast to the sail.
“That could become a more mainstream sailing solution down the track,” Bouzaid acknowledges. “Lots of people have tried that sort of thing. Inflatable wing shapes and double sided sails are different ways of creating more efficient wing shapes. It is definitely conceivable that we will see this type of sail being used on production, cruising type boats in the future.
“There has always been trickle down from the America’s Cup. Most recently we have seen foils being the big thing and already we are seeing cruising multihulls on foils. Also, the Vendee Globe type boats, particularly Alex Thompson’s, have shown what can be done with foils in monohulls.
“Maybe the next big thing will be wing-type mainsails with double luffs.
“It is really not that new. Kent Luxton was playing around with double sided headsails in the 1983 America’s Cup,” he says in reference to the fellow New Zealander who was a sailmaking partner with Tom Schnackenberg back in 1978 and has three America’s Cup and six round the world campaigns on his resume.
“What happens with these ideas, though, is that new technologies and better materials come along and make things possible that were not available when they were first conceived.”
Clearly a big challenge facing the design teams for the next Cup cycle will be generating sufficient power to lift the monohulls onto their foils as early as possible. He who foils first in any given condition will reap huge benefits, so the design race is likely to concentrate heavily on the rig and sail plan.
Bouzaid doubts that a soft wing will achieve quite the same degree of control and efficiency as a multi-element hard wing of the sort we have seen in the past two America’s Cups, but he has no doubt it will be much more efficient than a conventional mainsail.
“It will be interesting to see what evolves.”
As a cost-cutting measure, the new America’s Cup rule is likely to ban tank testing of hulls and wind tunnel testing, the argument being that computer modeling and simulation are so accurate that physical testing is not required.
However, Bouzaid, who has just returned from a week of testing at the Southampton wind tunnel, believes there is still a place for physical testing in sail design.
“Airflow is much more random and complex than water,” he argues. “Every shift in direction and strength has a direct influence on the flow over the sail. Then, adding to the complexity, the sail shape changes with every trim adjustment, making accurate modeling extremely challenging.”
Running CFD tests on every permutation becomes very time consuming. The computer may be more accurate in the end, but in two days at the tunnel, Bouzaid says you can run hundreds of tests and get a pretty good idea of these sorts of issues.
Where computer modeling has advanced is in predicting how different sail shapes will perform, so less physical testing is spent on that aspect of design. “In the past we used the tunnel for testing shapes and how the sail would fly. Now the tunnel is used more for analysing interactions between multiple sail combinations and the impact on balance and helm loads.”
This is particularly relevant in superyacht applications, where more complex rigs are seeing greater use. As yachts become larger, the sloop configuration has about reached its limit because of bridge heights on key sailing routes like Panama. To avoid going into the complications of hingeing or telescoping masts, this has seen greater use of ketch rigs and even multiple mast arrangements on vessels such as Maltese Falcon and Black Pearl.
“On some of these big yachts, you see sail plans with five or seven sails working at any one time, with lots of interactions going on between them. This has a significant impact on balance and helm loads and the tunnel is useful for analysing those forces.
“In the old days, this didn’t matter so much because superyachts tended to use hydraulic steering. Now, superyacht owners enjoy sailing their boats and having the feel and feedback of manual steering, but they don’t want it to be so loaded up that you have to have two hefty crew swinging on the wheel.”
Already, some of these very large yachts are using real-time load sensing and wind strength and direction inputs to automate sail trim and even reefing. As CFD analysis continues to become more adept and faster at modeling real time airflow, Bouzaid predicts that that it could become part of the management systems of more high performance cruising yachts, even foiling types.
Whether the rulemakers of events like the America’s Cup, Volvo and Vendee Globe would allow any level of automation in sail management is doubtful, but realtime performance analysis programs might well be integrated with CFD to inform competitors on how to optimise trim.
At Doyle, Bouzaid says, the design team uses CFD and FEA programs as well as a commercial sailmaking package called Sailpak. Developments in this field move so fast that he believes in-house software is not cost effective. “It makes much more sense to leave it to the program developers to conduct the constant research and development required to keep pace with progress, while we concentrate our research and development effort on our products.”
Sailmaking software has become so sophisticated that all the functions, from early-stage design to full structural engineering and aerodynamic characteristics to creating a file that will instruct machines exactly how to construct the material, are fully integrated into a single package. “It has progressed a lot in the past five years, so there are incredibly accurate tools available on the market.”
At the same time, he firmly believes that old fashioned analogue values like experience and knowledge and a ‘sailmaker’s eye’ remain an important part of the process. Along with the science, there is still place for the sailmaker’s art.
The makeup of the Doyle design team reflects this combination. A number of the team members are graduates from the former Yacht Design programme at the Auckland University School of Engineering, where theoretical work in CFD and FEA played a major role.
David LePelley, who headed the university programme, is now also at Doyle as head of research and management for the Stratis product. Between them, this group represents significant firepower in state of the art computer-based structural and performance modeling.
“Then, alongside them we have more experienced sail designers, who have been doing this for up to 30 years, so they bring a more knowledge-based approach to the equation. It makes for a nice blend of talents and skills on tap for our projects and can advance new ideas very quickly. It has allowed us to not only develop our design processes, but also our Stratis product, which is under a continuing cycle of research and development.”
Uniting both the science and art sides of this equation is the fact that all the design team members are active sailors, bringing a passion for the sport and a practical hands-on knowledge to bear on every aspect of their work.
“When you are dealing products like ours, which are very much custom, bespoke-type sails, experience and knowledge, alongside all the theoretical expertise and technology, is what it is all about.”