Welcome to the home of soft wingsails, sails of the future!

March 1st, 2018

A few days ago media pompously announced a ‘revolutionary’ soft wing sail by ETNZ ‘design geniuses’ as ground-breaking, state-of-the-art technology sailing rig.

There are some points that should be addressed here.

1. Kudos to ETNZ for being the first AC team ever to start working on the idea of a soft wingsail as the long due optimal solution.

2.  Any revolutionary or ground-breaking technology must be patentable, by definition.
Strangely, there is nothing here that could be patented.
A double-luff sail was patented by L. Francis Herreshoff nearly a hundred years ago.
Numerous other ‘double-surface’ designs include Princeton sail-wing (1952), Wharram’s Tiki soft wingsail etc …

3.  After the new AC75 foiling monohull concept has been revealed, Grant Dalton said:
 “Once foiling, the AC75 has the potential to be faster than an AC50 both upwind and downwind.”

Easy to say, but impossible to achieve with this particular ‘state-of-the-art’ wingsail, as its shape is inferior to the shape of the clumsy AC50 wing (which is btw far from ideal).

The proposed wingsail is certainly aerodynamically superior to conventional single-ply sail, but not enough to keep the AC75 on its foils. Its section could not be found in any of numerous catalogues of tested and proven wing sections. ETNZ’s design geniuses apparently did not pay attention to things like the wing’s maximum thickness and its position.

If an aircraft had such wings, it would fly as an old fashioned hang-glider. In forty years, aeronautical engineers have nearly reached perfection. Sailing rig designers lag behind them by fifty years.

Finally, from the ETNZ website: As with all America’s Cup class developments weight is always a big issue, but especially so with the AC75’s because of their self righting ability it is important to keep weight aloft to a minimum.
Since when the weight aloft is a big issue for ETNZ?

Previous America’s Cup holder, another team of ‘design geniuses’, set the AC50 Class Rule 12.10: The weight of the wing in wing measurement condition shall be not less than 870 kg, and the center of gravity shall be not less than 12.700 m above the wing rotation point.

In other words, going below that minimum was not allowed, but going above was allowed. Was weight aloft really a big issue? Did ETNZ protest against this idiotic rule? Anybody else? What a shame…


February 2nd 2018

After the new AC75 foiling monohull concept has been announced in November 2017, Emirates Team New Zealand and Luna Rossa have been working on Class Rule, which is to be issued on March 31st 2018.
Besides overall parameters such as length, weight and sail area, the Rules will cover specifics on materials, the types of appendages, hydraulic and electronic systems - almost every aspect of the design.

Sailing rigs, as the essence of sailing, used to be covered by rules in the past. Should the teams be allowed to choose what suits them best now?

Emirates Team New Zealand design coordinator Dan Bernasconi on why a class rule is so vital in the America’s Cup:

"In some ways, designers would love to work without the constraints of a rule, but in practice it's important to have a comprehensive set of constraints to keep costs under control; if no limits were set, the wealthiest teams could gain advantages by out-spending their competitors using rare materials, extremely complex systems, and countless iterations of components.” 

The same rhetoric we heard from Oracle design team while they were in charge of writing the Rule. What they ended up with was a clumsy, complex, fragile and very expensive rigid wingsail, seemingly meant to give advantage to their extremely wealthy team. Luckily, they were outwitted.

From the ETNZ: “An underlying principle has been to provide affordable and sustainable technology ‘trickle down’ to other sailing classes and yachts. Whilst recent America's Cup multihulls have benefitted from the power and control of rigid wing sails, there has been no transfer of this technology to the rigs of other sailing classes.”

Artemis Racing has a similar line of thought:
“The boat and race format must be seen as bringing the sport of sailing forward and inspiring young and future generations.”

True, the Oracle’s ‘cost-saving technology’ was impossible to trickle down to sailing in general. What will the ETNZ come up with?

In Wing Sails Co. we firmly believe that a sailing rig that is inefficient, heavy, complex, expensive, un-reefable and un-stowable should be banned by the coming rules.

Therefore, if both conventional, soft sails and rigid wingsails are excluded, what is left? Soft wingsails, only soft wingsails, and nothing but soft wingsails.
Enough said.

Below, you will find comments on certain issues from previous AC campaigns.

As the long-awaited Class Rule for the AC35 has been released on June 5, 2014, this comment is being added on top of the previous one, which will stay in memory of a sailor who lost his life in an unexplained capsize.

Only a naive follower could have expected any substantial departures from the Rules for the AC34. Even an insane rule on minimum weight and the center of gravity of the wing remained, of course with smaller figures, yet big enough to require limiting the allowed true wind speed to 25 knots. (12.10 The weight of the wing in wing measurement condition shall be not less than 870 kg, and the center of gravity shall be not less than 12.700 m above the wing rotation point.)

Nobody can defend this rule, because it does not make any sense at all - except that it recklessly discriminates against the idea of lighter wingsails. Well, they can agree on standing on their heads while racing, and nobody has the right to question it - unless an injury or life threat is recognized. And only then might an intervention take place - but who would intervene, and how?

From www.sailingscuttlebutt.com:

"An inquest into the death of British Olympic medalist Andrew Simpson (36 yr) occurred on May 21, 2014 in Bournemouth, England. Simpson had lost his life in an America's Cup training accident with the Swedish Artemis Racing team on May 9, 2013."

A yachting journalist reported briefly: "There was no attempt to apportion blame, nor was there any attempt to explain the cause of the accident beyond the fact that the Swedish AC72 was bearing away in 20 knots of breeze in choppy waters, apart from one hint, from Adam May's report that: "the port hull dug in and folded." No blame for this was apportioned. "

So, why did the port hull dig in? Look for a hint in these incredible 'minimum weight' rules!!!

Since that sensational BMW Oracle's victory over Alinghy in 2010, the whole sailing world has been buzzing about wingsails. Many a sailor still believes the technology behind the AC machines will eventually trickle down to everyday sailing. What could possibly trickle down: rigid wingsails, hydro-foils or perhaps grinding like crazy? Have we seen a single leisure sailboat using such a superior sailing rig since? No, and we never will - unless an entrepreneurial spirit steps in and makes fun of the Oracle expert approach.

To lift on its foil(s), an 'everyday boat' must reach a certain speed which cannot be provided by inefficient, thin, cloth sails. If the rigid, heavy and complex Oracle wingsails could provide such a speed, we would have witnessed regular boat design progress not only in the last couple of years, but in the last couple of decades of exploiting this not-very-smart design in Little America's Cup and his big brother in 1988.

So, forget about trickling Oracle's high technology down to millions of recreational sailors and racers. Wingsails that can do the job MUST be soft and light!!!

Several years ago a big project named "Wind Assisted Shipping" was launched. It was based on this design, for its efficiency, feasibility, versatility, lightness, simplicity and ease of handling. The project was abandoned after three years, mostly due to the incompetence of the R&D team from Massey University in Auckland, New Zealand. However, a London based shipping company wasted no time on either thin sails or rigid wingsails, and immediately focused on this soft wingsail. At 240m LOA, their freighters would be the largest sailing vessels ever.

On the other end of the scale is my long-proposed micro-sailboat, about 3m long and 70cm wide, and the only sailing monohull easily paddleable for its narrowness. It definitely has the potential to become a new water sport.

Visionaries, entrepreneurs, sailmakers or boatbuilders thinking about new projects and products might find a better fit between these two extremes.



At the end of October 2012, after the Oracle Racing's disaster, I sent the following letter to the editors of several sailing magazines and forums. Those of the Sailing Anarchy and Scuttlebutt were brave enough to publish it, provoking angry responses by some Anarchists.

Here it goes:
"I've read and watched recent stories about the last AC72 monster cat capsize.
I've been following the America's Cup races for the last 20 years as well, and cannot recall a single accident of this type.

By definition, multihulls are much more stable vessels than monohulls - aren't they?

Yet, monohulls, though slower, do not capsize to this 'epidemiological' extent, and do not suffer in such material damage terms. Alarmingly, the AC boats capsizing has become notorious, but nobody has ever questioned the issue.
Even the 'Capsize club' has been established, with membership proudly offered to most of the AC45 teams. Even formidable Russel Coutts pierced the wing with his head first!
What's going on? Where are the designers' comments? Where did the 'investigative journalism' disappear?
I'll give you a clue: the rigid wingsails are too heavy. Naturally, rigid things are supposed to have certain weight, and in this case it is a bit over the limit. Can AC wingsails be lighter? No, they can't - if they are to be solid. Why they must be solid? Because, by today's definition, wingsails are of solid, rigid, fixed, hard nature. Only jibs, genoas, gennakers and spinnakers can be soft.

Why this is so? Nobody knows ... except some weird minds.

But if the AC wingsails were lighter - why not soft? - there would be no capsizes, risking lives and million dollar damages!

Are there soft wingsails? Of course there are. Because rigid wingsails are basically useless for any other sailing purpose except those short elite AC races, many people brainstormed the idea of having a sail shaped and performing like a wing, yet having features of conventional cloth sails - weight, price, ease of manufacturing and handling.

And I am just one of them.

On the other end are strong, well positioned guys, who adopted the old idea of a flapping solid wing, a concept limited by 2D thinking, lacking imagination and inventiveness.

This sick brainchild survived decades, protected by vested interests, stubbornness, closed mindedness, vanity...regardless of price somebody might pay for its apparent deficiencies.

Do you think something is going to change if an AC crew member dies in a future capsize, which is inevitable and pending?

No, nothing will change. But remember what I've just told you."

And it happened on May 9, 2013. A top sailor has died, leaving his family, friends and community devastated. We all know there are some risks involved in sailing, but those risks must be recognized and diligently reduced to minimum.

The issue of  AC cats easy capsizing is as old as the boats themselves, but nobody has ever 'recognized the risks' hidden in the Rule 10.12, and challenged it:

The weight of the wing in wing measurement condition shall be not less than 1325 kg, and the center of gravity shall be not less than 17.000 m above the wing base plane.

(Interestingly, the minimum CG height in AC72 Class Rule version 1.0 was set at 15.25m, and later, in version 1.1, increased to 17m. Were the rule makers providing more room for heavier wings, instead of minimizing the risk of capsize? What led them to arrive at these exact figures? Fine calculation, emulation, comparative analysis ... or actual measurement of a finished stupid wing taken for granted?)

The rig's weight and the CG height are among the most crucial parameters in sailing, and the basic principles behind them are taught at physics courses in elementary schools. Higher the values, lower the stability, right? Have the AC organizers, designers and rule makers skipped these lessons? How else could this insane, dangerous limiting from below be explained?

From an interview with Paul Cayard in November 2011, we can see that Artemis was concerned with the weight aloft from the beginning:

"But when you scale up to a wing 130 feet tall, how do you control the beast? The first Artemis wing is under construction in a special facility in Valencia, Spain, Cayard says, and to control the moving parts in that wing, “We have 38 hydraulic cylinders. We want to avoid running hydraulic piping to each of them, because that would be heavy, so we have electrovalves embedded in the wing to actuate the hydraulics. But if you had two wires, positive and negative, running to each electrovalve, your wing would look like a PG&E substation, and that’s heavy too, so we use a CAN-bus [controlled area network] with far fewer wires. Still, it’s incredibly complex."

Is anybody out there curious to know the secret of the final Artemis wing's weight?

The basic slotted rigid wing type was developed decades ago for the Little America's Cup (nowdays known as C-Class), and through several generations of Patient Ladies evolved into the version still in use. It was fairly light, say 0.5 lbs per sq ft, but by increasing its area almost tenfold for its big brother, the AC wing's weight increased progressively, so its specific weight jumped from less than 2.5 kg per m2 to at least 5,2 kg per m2!

Moreover, its slotted section is highly imperfect, something impossible to find on any aircraft, particularly gliders whose model wings should be followed.
Consequently and not surprisingly at all, the AC72s have been named "wild untamed beasts".


The AC rule was written with fairly tight constraints, intended to limit any substantial development by the challengers. Not exactly one-design, but pretty close to it, letting the design teams figure out small differences only. Ironically, instead of limiting spendings, the whole project wasted millions in damages - and a human life. Then in order to save it, they limited the only other thing left - the allowed wind speed.
Who to blame for this total fiasco - Oracle, who, as the America's Cup holder, sets the ground rules for the competition, Artemis that further 'improved' the wing, or all challengers who agreed to the rules?

In an interview for NY Times from 9.7.2013, Loïck Peyron commented on the tragic accident two months earlier: “The danger was known in this case,” Peyron said. “We’ve already seen one capsizing a few months ago, and we know these boats are not very stable because the wing sails are too big. The pity is that with smaller wings, they could be safer and faster.”

What are you talking about, Loïck? Do we know something the rest of the sailing world does not?

Comparing AC72 to AC45 in November 2012, Loïck Peyron said: “They don’t have that much in common.  Proportionally, the AC72s are much more unstable ... everything is that much heavier, including the wing, of course and the centre of gravity is not that well placed, as it is higher up.  On top of that, there is a lot of inertia… And of course, you can’t take in a reef…”

Unfortunately, this great sailor's expertise couldn't save another great sailors's life.

Could it prevent future losses?

The Rule 10.12 must be revised, the issue  rectified at its root and not by introducing 'buoyancy aids, body armor, crew locator devices, hands-free breathing apparatus and high visibility helmets', and the rule makers held responsible. If a member of my family died in such a stupid accident, rest assured the case would end up at the court.

It can often be heard that AC72 boats belong to the space age and technology. In a way, this is true - but space ships designed by the AC experts would definitely fall apart a couple seconds after launching.

The America's Cup is the world's heritage, not a private property. This way the organizers have already spoiled the event, and are jeopardizing its future.

Finally, where is the sailing in general heading now? Over the past three years sailors have realized that wingsails offer much more than inefficient thin sails still proudly produced by the best sail makers in the world. Is there anything in between clumsy hard wingsails and practical but inefficient thin sails?