sailboat wing

• Yachting World
• Digital Edition

How wingsail technology could revolutionise the shipping industry

• October 26, 2022

Do superyacht designers have the answers to the future of efficient sailing and shipping? Mark Chisnell reports on why variants of wingsail technology could be coming to an ocean near you

On a summer weekend there’s always a bustle of activity on the foreshore at Hamble-le-Rice, on England’s south coast. The whirr of electric air compressors has been the soundtrack to the rise and rise of the inflatable paddleboard . And it may be about to initiate another transformation, simplifying sailing to the point where it returns to its birthplace; commercial shipping.

Matt Sheahan reviewed the Inflatable Wing Sail (IWS) for Yachting World more than three years ago and was impressed by the invention of Edouard Kessi and Laurent de Kalbermatten. Based on an unstayed, telescopic mast, the IWS inflates via an integrated air compressor to a surprisingly low pressure, just two millibars.

It creates a soft, symmetric wingsail with many of the efficiency advantages of a hard wingsail (amply demonstrated in America’s Cup and SailGP racing) but none of the problems – it’s very simple to raise and lower, and just disappears down to the deck when you don’t need it. Matt predicted that the much-simplified handling could mean a significant future for the IWS in superyachts and commercial shipping.

The simple to handle Inflatable Wing Sail (IWS) we featured in 2019

Simplifying the way that sailboat rigs work is far from a new idea. The IWS follows in the wake of many of these initiatives with its unstayed mast, an idea that has its origins in the Chinese junk rig.

Gary Hoyt’s Freedom Yachts utilised this approach in the mid-1970s. Meanwhile in the 1980s, a building beside the very same River Hamble produced the AeroRig, a free-standing mast with a rotating boom on which both headsail and mainsail were set. The forces were easily balanced and controlled by the mainsheet alone.

A descendant of the AeroRig is the Dynarig, developed by Dykstra Naval Architects and built by Magma Structures in the UK for two spectacular superyachts, the Maltese Falcon and Black Pearl . A recent partnership agreement with Southern Spars means that the Dynarig will now be developed with the support of one of the marine world’s most sophisticated technology providers. The rig is targeted at the people who want to keep it simple, and this can include superyacht owners interested in reducing crew numbers and handling issues.

Dykstra has a Wind Assisted Shipping Project (WASP) in process, a multipurpose cargo ship which uses the Dynarig masts as cranes, and is working with Veer on the world’s first emissions free cargo fleet. The Dutch design house, responsible for some of the most iconic superyacht and J Class projects, also tells us that it is currently working on a couple of new classified Dynarig superyacht projects.

This is where most of the momentum is headed with these new technology rigs in the superyacht world. VPLP is perhaps the world’s most successful yacht design groups since Marc Van Peteghem and Vincent Lauriot Prévost set up their business in 1983.

They’ve won the Vendée Globe , the Jules Verne , the Route du Rhum , and in 2010 the America’s Cup with the huge wingsail on BMW Oracle. “Marc [Van Peteghem] saw the potential of that highly efficient automatable wingsail,” explained Simon Watin, president of their maritime division.

“He’s been at the forefront since that period, really pushing in parallel the maritime transportation and the yachting together,” continued Watin. VPLP started drawing the concept in 2016 and built the first Oceanwing to fit on a small trimaran. It’s an automated wingsail that hoists on an unstayed mast – similar to the IWS but using battens to create the wing’s shape, rather than inflation. It’s a two-element rig though, allowing for a more efficient foil and higher performance. VPLP built two 32m2 Oceanwings for Energy Observer , a former racing catamaran now circumnavigating as a technology platform. They also started to pitch eye-catching concept designs into the superyacht community.

“The people we are looking to convince are people that would normally go for a pure motor yacht,” explained Watin, “and who would not be so much interested in the sailing aspect itself.” Watin pointed to the gains in fuel economy, range, comfort and autonomy. The Seaffinity is a streamlined, concept trimaran from VPLP, “with a large main hull and two smaller floats featuring two Oceanwings, one behind the other,” explained Watin. “And this is really an illustration of a new superyacht that could have been a pure motor yacht, but actually benefits from the Oceanwing.”

Dykstra’s Dynarig projects, made famous by Maltese Falcon and Black Pearl (pictured), are being adapted for shipping

Superyacht concepts

Another VPLP/Ayro collaboration has resulted in the radical Nemesis One superyacht concept, a 101m/332ft foiling catamaran capable of 50-knot speeds. The fully automated, push-button craft uses a modified Oceanwings wingsail which can furl and reef and automatically adjusts its angle of attack. There’s no question that this and the Seaffinity are striking vessels, and that the technology could make a significant dent in the operating carbon footprint of yachts that might otherwise have been engine-only.

The first large scale Oceanwing will be a commercial shipping project. The step came when VPLP and the shipping company Alizé successfully bid for Ariane Espace’s tender for a new concept ship that could carry parts of the Ariane 6 rocket from European ports to French Guiana. Once it had the contract, VPLP created Ayro as a separate business to develop the cargo ship Canopée. She is scheduled to launch in late 2022, at 121m long, and will be powered by four 363m² Oceanwings set on 36m masts. VPLP thinks the wingsails will reduce fuel consumption by 15% without compromising speed.

“The technical concept is aerodynamic efficiency with the solid sail with two elements: so reaching maximum lift coefficient. Automation; so no lines, no unnecessary human intervention for trimming, adjusting, hoisting. And much less impact on the deck plan, which is quite major, especially for a superyacht,” said Watin.

The WASP uses its masts as cranes to unload cargo

The difference in the physical and mechanical realisation of the Oceanwing for superyacht and commercial shipping markets is interesting. The version for merchant ships will stick to industrial suppliers as far as possible – electric actuators that would normally mobilise cranes, for instance. The wing will use a reinforced PVC fabric skin, the type of material that would make a truck tarpaulin.

The masts will remain in place in normal use, and the fabric wings will raise and lower on cables powered by electric rams, so the sail area can easily be reduced. A tilting mechanism will allow the mast height to be reduced for ports and bridges.

Unsurprisingly, the superyacht version will be a lot more sophisticated, but is still based on the same self-standing mast and 360° rotation of the sails. “We would use higher technology material, lighter fabrics as well… and for the yachts, we have to be more cautious about the weight of the installation itself, because the sail area is going to be quite a bit larger in comparison to the boat. And obviously, the design is going to be important so we will package all the actuators in a much nicer way – you don’t want a ram sticking out.”

The 48m VPLP design Evidence uses automated and stowable wing sails

Bold initiatives

Ayro is now responsible for all the design and engineering on the Oceanwing, with its own 35-strong design office, but VPLP remains involved. “Ayro has successfully raised quite a bit of funding to sustain its growth,” Watin told me.

It was 2019 when Matt Sheahan made his prediction for the future of the IWS in his Yachting World review, and three years later it appears that the commercial shipping development is also well ahead of the superyacht market.

The WISAMO system is an initiative from Michelin, with two-time Vendée Globe winner Michel Desjoyeaux associated with the project and testing. It’s the same concept as IWS, an inflated wingsail, set on an unstayed telescopic mast.

“When I discovered that system, I thought it has checked a lot of boxes compared to other systems,” said Desjoyeaux. “It has a plug and play system which is very easy to install and use, whether it is for a refit, meaning an addition to an existing boat, or for a newly built ship; you lower the mast into the boat, plug it in and off you go. Once you are out of the harbour, you push a button and the machine does everything. It unfurls the wingsail and automatically chooses the correct setting for cargo ships. This is crucial because there aren’t many crewmembers on the bridge, and they don’t necessarily know much about sailboats. They need a system that operates autonomously.”

VPLP Oceanwing projects on Energy Observer

At the beginning of 2022 Michelin announced a partnership deal with Compagnie Maritime Nantaise to test the WISAMO. The system will be fitted to one of their roll-on roll off vessels travelling between Bilbao in Spain and Poole in the UK. The plan is to have the ship in service by the end of this year. Meanwhile, tests with Michel Desjoyeaux’s own boat continued through last winter in the Bay of Biscay.

Michelin are claiming the system could save up to 20% on fuel costs. It’s in the same ballpark as the Oceanwing, and while it sounds good – particularly at today’s fuel prices – it’s actually only half of what the shipping industry needs to achieve by the end of the decade.

Reducing emissions

The shipping industry pumps out a lot of carbon dioxide – the most recent (2012) estimates being that shipping is responsible for 2.2% of global emissions. The International Maritime Organisation, an agency of the United Nations, has published a strategy for reducing carbon. Global shipping must achieve an average 40% reduction by 2030, increasing to 50% by 2050. The European Union is acting to give these targets legal force, and the first deadline is just eight years away. The task is immense, and the clock is ticking. That’s why the money and energy pushing these new sailing technologies forward is coming from commercial shipping.

Radical superyacht concepts such as Seaffinity feature Oceanwing wingsails from VPLP

One thing that’s been learned in the 150 years since sail last dominated the world’s oceans is that changing the world’s merchant shipping fleet takes time. In 1866, the year of the Great Tea Race, an auxiliary steamer left China eight days after the clipper ships and it arrived in London 15 days ahead of them. Steamships already had a significant speed advantage, but it was more than another 80 years before the last sailing ship ceased trading. This is the problem for the shipping industry; ships are built to last. The world once again needs to restock the entire global merchant fleet with a new technology, but this time there’s a deadline.

The same pressure is unlikely to be felt in the superyacht market for a while, and perhaps it never will. Still, once these new technologies have been developed and proven in the highly competitive shipping industry, it seems likely they’ll start to migrate to superyachts.

No easy options

There are many possible technical solutions but the easy changes – more efficient routing through weather systems for instance – will not get the industry to anything like the 40% required by 2030. The developments that will – new propulsion systems, fuel sources or hull designs – are still in development and/or will require massive capital investment. It’s taken a while, but the shipping industry has finally woken up to the scale and the timescale of the challenge it faces.

“They’ve got a massive problem on their hands,” said Simon Schofield, chief operating officer of BAR Technologies, a spin-off from the British America’s Cup team led by four-times Olympic gold medal winner, Ben Ainslie.

Nemesis One is a 101m foiling supercat concept capable of 50 knot speeds thanks to a fully automated Ayro Oceanwing rig

“In the last two years we’ve seen a marked difference in the industry. Two to three years ago when we were talking about this [wingsail] technology, people were like, ‘Yeah, it’s nice. People have been talking about this for years, but no one really wants sails…’ And now it’s, ‘How quickly can we have wings? What else have you got? We’ve got to move, we’ve got to get going.’”

Unsurprisingly, there is no shortage of people trying to solve this problem. The reward for developing any cost-effective way of reducing a significant chunk of those 40% of emissions will be a massive new business. The scale of the shipping industry is enormous, it’s a global business with a total value of more than US$14 trillion. So, there’s no shortage of ideas either, and kites were early leaders in this field.

The SkySail was a stand-out that got tested at full scale, installed in a custom-built ship, the MV Beluga Skysail , and tested on an Atlantic crossing in 2008 after 10 years of development. It fell at that hurdle, with the company turning instead to developing airborne wind energy systems for power production. The fate of the shipping project is sadly recorded on their website: ‘The SkySails propulsion system for vessels is currently not marketed any more.’ There’s no mistaking the significant risk in these ventures.

Fortunately, risks have never stopped people trying to innovate and there are plenty more projects with potential. The Flettner rotor is a tall, smooth cylinder mounted vertically, that rotates in the airflow passing the ship. It uses the Magnus Effect (the same thing that causes a spinning ball to curve in flight) to generate a force that helps to push the ship along. Norsepower have already installed a rotor on one tanker and it provided just over 8% fuel savings – good, but still nowhere near enough.

Oceanwing projects also shown here on cargo ship Canopée due to launch this year

It’s now the wingsail that seems to be grabbing the bulk of the investment. A Swedish group, led by Wallenius Marine, has formed a joint venture with Swedish industrial company Alfa Laval to develop the Oceanbird, a wind-powered car carrier with fixed wingsails that will stretch an extraordinary 100m into the air.

More sailing ships to come

In France, Neoline have developed a more conventional sailing cargo ship and agreed a letter of interest for its construction. They plan to use the Solid Sail being developed by the French shipbuilding and fleet services company Chantiers de l’Atlantique. It’s a freestanding mast with a rotating boom setting a fabric headsail and solid panel mainsail – panels that Multiplast are building.

There are several projects in the UK. British yacht design firm Humphreys Yacht Design and sailing software tools designer, Dr Graeme Winn, are involved with Smart Green Shipping. In late July, they announced a £5m investment from a mix of private industry and Scottish Enterprise for a three-year R&D project to develop and test their FastRigs wingsail and digital routing software. They plan to put a demonstration unit on a commercial ship by 2023.

Also out of the UK is the Windship project, with a board of directors that includes yacht designer Simon Rogers and former Sparcraft director David Barrow. They’re proposing sets of three vertical wings, each 35m high.

Oceanbird is a Swedish programme with a car carrier in development using folding 40m high wingsails. The company estimates each sail will save around 480,000 litres of diesel per year

“We believe,” Simon Schofield told me, “that wind technology has become mainstream in shipping… we’re seeing announcements almost weekly of new technologies being trialled and fitted to ships and we are set up specifically with a supply chain for volume. We’re doing a run now, but we want to be doing hundreds next year.”

Yes, that’s right. Hundreds. If there is such a thing as first-mover advantage, BAR Technologies appear to have it.

BAR started the WindWing project with a computer simulation, but merchant ships presented new problems. “The ships have a yaw balance [weather or lee helm] problem,” explained Schofield. “They’re not designed for wings. So, you’ve got to monitor rudder limits.” This is exactly the kind of problem that’s fundamental to designing well-behaved, fast and comfortable superyachts, and it’s no surprise the same approach was taken by VPLP with a similar background in elite yacht racing design.

BAR Technologies predicts there will be hundreds of ships using its WindWings by next year

Complications

The problem is even more complex with commercial ships. The leeway the wings induce has other side effects. The loading on the propeller changes, and that impacts its efficiency. “We also needed to model the engine plant, because we are moving engines away from their optimum efficiency points, so their fuel consumption changes,” said Schofield. Eventually, using these tools, they developed the design parameters for the WindWings.

“They are three-element, rigid wingsails,” said Schofield. “The first ones we’re doing are 37.5m aerodynamic span, about 20m in chord and rising to about 45m off the deck. So big bits of kit… We operate in up to 40 knots of true wind speed, with a 25% gust factor on top. So if it’s 40 gusting 50, that’s fine.” After that the WindWings are feathered, much like a wind turbine.

Despite the advanced state of BAR Technologies’ WindWings project, it’s probably too early to predict who the big winners will be in this race. In fact, given the demand from the world’s merchant shipping fleets, it’s likely there’ll be several.

We can also be sure all this energy, innovation and investment is going to produce significant advances in sailing technology. Perhaps, in a few years’ time, the gentle whirr of electric air compressors will have found their way from the paddleboards on the beaches of the River Hamble, to former motoryachts in the river’s many marinas.

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What’s In A Rig? – Wingsail

By: Pat Reynolds Sailboat Rigs , Sailboats

What’s in a Rig Series # 8 – The Wingsail

Although wingsails or rigid wings have risen to the limelight in the contemporary sailing world with the America’s Cup now employing the technology across the board, they are in no way a brand new concept. A sail, after all, in its purest form is essentially a wing. So, through the decades, many designers, looking for optimum performance, have of course instituted rigid wings (just like that of an airplane). A notable example would be the so called Little America’s Cup, a long-standing catamaran contest based around the pursuit of pure speed.

The efficiency of a hard wing has never been in question. They sail upwind higher and reach faster. Their purity of engineering allows for maximum proficiency. When compared to a solid wing, a soft sail is full of hard to manage variables. The shape, components and accompanying systems are no match for a wingsail. In many ways, a conventional sailboat rig is fighting against itself to do what it’s meant to do. Shrouds and stays are battling to keep everything in place while a sailor adjusts control lines incessantly. It’s not perfect. However, the relative practicality is another issue. A very large unbending non-folding solid structure has its obvious drawbacks. How do you stow this thing when you’re done sailing and how do you reef it if the breeze starts blowing and, for the traditionalists, where’s the romance in a big airplane wing sticking up from the front of the boat?

Before we address those questions, let’s look at how this rig works. Using the America’s Cup boats as great examples, a wingsail itself is usually composed of two parts and the surrounding system is essentially three ingredients.

The sail has a forward and trailing element. The trailing element is like the flaps on an airplane wing and the angle between the two elements is called camber. Increasing the camber (angle) produces power. If the power becomes too much, which it often does, another control system comes into play that deals with “twist”. Twist allows the ability to depower the boat by twisting the wing so wind can spill off.

After camber and twist, the third major aspect of control on these quite simple wing setups is the mainsheet. Like a normal mainsheet, it lets the sail out, but unlike a soft sail, a rigid wing doesn’t power up downwind, which is why soft genoas are often part of the sailplan.

So, without argument wingsails are more efficient engines, but, as we stated, are not nearly as practical as soft sails. Are you sensing the idea of a hybrid coming around the bend? Yes, in fact, world renown cruising boat manufacturer Beneteau has been developing just such an innovation. They have a soft wingsail prototype installed on a production boat that blends the two concepts. It’s made of cloth so it can be broken down like a traditional scale but is, in every other way, a wingsail. It’s an unstayed mast with an airplane style wing that they say behaves very much like its rigid cousin.

So, lets revisit the particular questions we asked earlier and make sure we answered them. How is the wingsail reefed? By adjusting the aforementioned twist control, a wingsai is depowered, thereby reefed. How can this big wing thing be stowed? Well, with this hybrid idea, it’s lazy jacks and sail covers – we know how that works.

The last question is more difficult to answer…where’s the romance? The feeling, sounds and shape that soft sails embody date so far back into our collective history, it’s a bit heartbreaking to think they could possibly be replaced. There’s a certain humanity…a beauty and art involved in harnessing these inherent imperfections. We share this struggle and achievement with those who sailed before us. We have continually developed materials, hardware and better systems to get an edge, and are always happy when we succeed, but a radical refit, should it happen on a grand scale, is sort of jarring and sad.

Alas, this is the quandary of technology and advancement. Change bringth and taketh away. But don’t worry too much about it – in this modern day it seems 18-year old yellow, fading Dacron sails hung about on aging wires are still representing strong!

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How a Sail Works: Basic Aerodynamics

The more you learn about how a sail works, the more you start to really appreciate the fundamental structure and design used for all sailboats.

It can be truly fascinating that many years ago, adventurers sailed the oceans and seas with what we consider now to be basic aerodynamic and hydrodynamic theory.

When I first heard the words “aerodynamic and hydrodynamic theory” when being introduced to how a sail works in its most fundamental form, I was a bit intimidated.

“Do I need to take a physics 101 course?” However, it turns out it can be explained in very intuitive ways that anyone with a touch of curiosity can learn.

Wherever possible, I’ll include not only intuitive descriptions of the basic aerodynamics of how a sail works, but I’ll also include images to illustrate these points.

There are a lot of fascinating facts to learn, so let’s get to it!

Basic Aerodynamic Theory and Sailing

Combining the world of aerodynamics and sailing is a natural move thanks to the combination of wind and sail.

We all know that sailboats get their forward motion from wind energy, so it’s no wonder a little bit of understanding of aerodynamics is in order. Aerodynamics is a field of study focused on the motion of air when it interacts with a solid object.

The most common image that comes to mind is wind on an airplane or a car in a wind tunnel. As a matter of fact, the sail on a sailboat acts a bit like a wing under specific points of sail as does the keel underneath a sailboat.

People have been using the fundamentals of aerodynamics to sail around the globe for thousands of years.

The ancient Greeks are known to have had at least an intuitive understanding of it an extremely long time ago. However, it wasn’t truly laid out as science until Sir Isaac Newton came along in 1726 with his theory of air resistance.

Fundamental Forces

One of the most important facets to understand when learning about how a sail works under the magnifying glass of aerodynamics is understanding the forces at play.

There are four fundamental forces involved in the combination of aerodynamics and a sailboat and those include the lift, drag, thrust, and weight.

From the image above, you can see these forces at play on an airfoil, which is just like a wing on an airplane or similar to the many types of sails on a sailboat. They all have an important role to play in how a sail works when out on the water with a bit of wind about, but the two main aerodynamic forces are lift and drag.

Before we jump into how lift and drag work, let’s take a quick look at thrust and weight since understanding these will give us a better view of the aerodynamics of a sailboat.

As you can imagine, weight is a pretty straight forward force since it’s simply how heavy an object is.

The weight of a sailboat makes a huge difference in how it’s able to accelerate when a more powerful wind kicks in as well as when changing directions while tacking or jibing.

It’s also the opposing force to lift, which is where the keel comes in mighty handy. More on that later.

The thrust force is a reactionary force as it’s the main result of the combination of all the other forces. This is the force that helps propel a sailboat forward while in the water, which is essentially the acceleration of a sailboat cutting through the water.

Combine this forward acceleration with the weight of sailboat and you get Newton’s famous second law of motion F=ma.

Drag and Lift

Now for the more interesting aerodynamic forces at play when looking at how a sail works. As I mentioned before, lift and drag are the two main aerodynamic forces involved in this scientific dance between wind and sail.

Just like the image shows, they are perpendicular forces that play crucial roles in getting a sailboat moving along.

If you were to combine the lift and drag force together, you would end up with a force that’s directly trying to tip your sailboat.

What the sail is essentially doing is breaking up the force of the wind into two components that serve different purposes. This decomposition of forces is what makes a sailboat a sailboat.

The drag force is the force parallel to the sail, which is essentially the force that’s altering the direction of the wind and pushing the sailboat sideways.

The reason drag is occurring in the first place is based on the positioning of the sail to the wind. Since we want our sail to catch the wind, it’s only natural this force will be produced.

The lift force is the force perpendicular to the sail and provides the energy that’s pointed fore the sailboat. Since the lift force is pointing forward, we want to ensure our sailboat is able to use as much of that force to produce forward propulsion.

This is exactly the energy our sailboat needs to get moving, so figuring out how to eliminate any other force that impedes it is essential.

Combining the lift and drag forces produces a very strong force that’s exactly perpendicular to the hull of a sailboat.

As you might have already experienced while out on a sailing adventure, the sailboat heels (tips) when the wind starts moving, which is exactly this strong perpendicular force produced by the lift and drag.

Now, you may be wondering “Why doesn’t the sailboat get pushed in this new direction due to this new force?” Well, if we only had the hull and sail to work with while out on the water, we’d definitely be out of luck.

There’s no question we’d just be pushed to the side and never move forward. However, sailboats have a special trick up their sleeves that help transform that energy to a force pointing forward.

Hydrodynamics: The Role of the Keel

An essential part of any monohull sailboat is a keel, which is the long, heavy object that protrudes from the hull and down to the seabed. Keels can come in many types , but they all serve the same purpose regardless of their shape and size.

Hydrodynamics, or fluid dynamics, is similar to aerodynamics in the sense that it describes the flow of fluids and is often used as a way to model how liquids in motion interact with solid objects.

As a matter of fact, one of the most famous math problems that have yet to be solved is exactly addressing this interaction, which is called the Navier-Stokes equations. If you can solve this math problem, the Clay Mathematics Institute will award you with $1 million!

There are a couple of reasons why a sailboat has a keel . A keel converts sideways force on the sailboat by the wind into forward motion and it provides ballast (i.e., keeps the sailboat from tipping).

By canceling out the perpendicular force on the sailboat originally caused by the wind hitting the sail, the only significant leftover force produces forward motion.

We talked about how the sideways force makes the sailboat tip to the side. Well, the keep is made out to be a wing-like object that can not only effectively cut through the water below, but also provide enough surface area to resist being moved.

For example, if you stick your hand in water and keep it stiff while moving it back and forth in the direction of your palm, your hand is producing a lot of resistance to the water.

This resisting force by the keel contributes to eliminating that perpendicular force that’s trying to tip the sailboat as hard as it can.

The wind hitting the sail and thus producing that sideways force is being pushed back by this big, heavy object in the water. Since that big, heavy object isn’t easy to push around, a lot of that energy gets canceled out.

When the energy perpendicular to the sailboat is effectively canceled out, the only remaining force is the remnants of the lift force. And since the lift force was pointing parallel to the sailboat as well as the hull, there’s only one way to go: forward!

Once the forward motion starts to occur, the keel starts to act like a wing and helps to stabilize the sailboat as the speed increases.

This is when the keel is able to resist the perpendicular force even more, resulting in the sailboat evening out.

This is exactly why once you pick up a bit of speed after experiencing a gust, your sailboat will tend to flatten instead of stay tipped over so heavily.

Heeling Over

When you’re on a sailboat and you experience the feeling of the sailboat tipping to either the port or starboard side, that’s called heeling .

As your sailboat catches the wind in its sail and works with the keel to produce forward motion, that heeling over will be reduced due to the wing-like nature of the keel.

The combination of the perpendicular force of the wind on the sail and the opposing force by the keel results in these forces canceling out.

However, the keel isn’t able to overpower the force by the wind absolutely which results in the sailboat traveling forward with a little tilt, or heel, to it.

Ideally, you want your sailboat to heel as little as possible because this allows your sailboat to cut through the water easier and to transfer more energy forward.

This is why you see sailboat racing crews leaning on the side of their sailboat that’s heeled over the most. They’re trying to help the keel by adding even more force against the perpendicular wind force.

By leveling out the sailboat, you’ll be able to move through the water far more efficiently. This means that any work in correcting the heeling of your sailboat beyond the work of the keel needs to be done by you and your crew.

Apart from the racing crews that lean intensely on one side of the sailboat, there are other ways to do this as well.

One way to prevent your sailboat from heeling over is to simply move your crew from one side of the sailboat to the other. Just like racing sailors, you’re helping out the keel resist the perpendicular force without having to do any intense harness gymnastics.

A great way to properly keep your sailboat from heeling over is to adjust the sails on your sailboat. Sure, it’s fun to sail around with a little heel because it adds a bit of action to the day, but if you need to contain that action a bit all you need to do is ease out the sails.

By easing out the sails, you’re reducing the surface area of the sail acting on the wind and thus reducing the perpendicular wind force. Be sure to ease it out carefully though so as to avoid luffing.

Another great way to reduce heeling on your sailboat is to reef your sails. By reefing your sails, you’re again reducing the surface area of the sails acting on the wind.

However, in this case the reduction of surface area doesn’t require altering your current point of sail and instead simply remove surface area altogether.

When the winds are high and mighty, and they don’t appear to be letting up, reefing your sails is always a smart move.

How an Airplane Wing Works

We talked a lot about how a sail is a wing-like object, but I always find it important to be able to understand one concept in a number of different ways.

Probably the most common example’s of how aerodynamics works is with wings on an airplane. If you can understand how a sail works as well as a wing on an airplane, you’ll be in a small minority of people who truly understand the basic aerodynamic theory.

As I mentioned before, sails on a sailboat are similar to wings on an airplane. When wind streams across a wing, some air travels above the wing and some below.

The air that travels above the wing travels a longer distance, which means it has to travel at a higher velocity than the air below resulting in a lower pressure environment.

On the other hand, the air that passes below the wing doesn’t have to travel as far as the air on top of the wing, so the air can travel at a lower velocity than the air above resulting in a higher pressure environment.

Now, it’s a fact that high-pressure systems always move toward low-pressure systems since this is a transfer of energy from a higher potential to a lower potential.

Think of what happens when you open the bathroom door after taking a hot shower. All that hot air escapes into a cooler environment as fast as possible.

Due to the shape of a wing on an airplane, a pressure differential is created and results in the high pressure wanting to move to the lower pressure.

This resulting pressure dynamic forces the wing to move upward causing whatever else is attached to it to rise up as well. This is how airplanes are able to produce lift and raise themselves off the ground.

Now if you look at this in the eyes of a sailboat, the sail is acting in a similar way. Wind is streaming across the sail head on resulting in some air going on the port side and the starboard side of the sail.

Whichever side of the sail is puffed out will require the air to travel a bit farther than the interior part of the sail.

This is actually where there’s a slight difference between a wing and a sail since both sides of the sail are equal in length.

However, all of the air on the interior doesn’t have to travel the same distance as all of the air on the exterior, which results in the pressure differential we see with wings.

Final Thoughts

We got pretty technical here today, but I hope it was helpful in deepening your understanding of how a sail works as well as how a keel works when it comes to basic aerodynamic and hydrodynamic theory.

Having this knowledge is helpful when adjusting your sails and being conscious of the power of the wind on your sailboat.

With a better fundamental background in how a sailboat operates and how their interconnected parts work together in terms of basic aerodynamics and hydrodynamics, you’re definitely better fit for cruising out on the water.

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Welcome to Kitewing – Hand Held Wings

Welcome to the Kitewing website.

The Kitewing is a hand held wingsail designed for sailing on low friction surfaces. Sail over ice and snow with skates and skis, pavement with skateboards or rollerblades, mountainboards on beach or desert – it is all Kitewing terrain.

              Be sure to check out the new Skate Sails Wings Division of Kitewing! 

https://kitewing.com/skate-sails/

The American Skimbat online Magazine

  American Skimbat Winter 2024

American Skimbat Features new rigging techniques and Safe Sailing:check your ice!

American Skimbat Winter 2024

Contact Kitewing

[email protected]

Kitewing LLC Headquarters 135 Sanborn Hill Road Ext Grantham, NH 03753

Kitewing LLC Facebook Page Kitewing Sports Facebook Page Kitewing on Strava Lake Ice Squambats

Soft wing-sails are the next generation of sails 

Why soft wing-sails .

Why do we keep using sails like the old Dutch windmills rather than wings like the modern wind turbines?

Why do we try to make the sails look like wings rather than using the real thing?

Why do we use sails, knowing that wings are more efficient in terms of driving force and upwind pointing?

​ As a fighter pilot and an enthusiastic sailor for long time, I discovered that there are lots of similarities between flying and sailing, such as driving a machine on fluids, no brakes, windage effects on the bow / stern, the propeller walk, etc., However, the most and remarkable similarity is the use of lift force .

Airplanes use lift force, created on the wing due to the air flow around it, in order to hold the airplane up in the air. Sailing boats can use the same lift force, created on the sails as their driving force.

The answer to the questions "why" above was to make Omer Wing-Sail which is a simple structure wing-sail , easy to use, reliable, and good for all cruisers / cruiser racers in any weather condition.

Extensive sailing with the Omer soft wing-sail, strongly convinced me  that wing-sails are the next step in the evolution of sails.

Omer Wing-Sail

Why free-standing mast?

The idea of a mast without wires is foreign to most people. It is hard to fathom how a sailboat mast can stand, all by itself, without something to hold it up. However, those airplanes that long ago got rid of the wires holding the wings on in exchange for a spar, fly very safely. No one really thinks that the wing spar is not strong enough, and that an  airliner wing will fall apart.

Unstayed masts are designed to take the heeling and sailing loads the same way wing spars take the loads of the airplane.

The unstayed mast is held up by two parts - the heel fitting and the deck fitting. It puts no downward compression loads on the hull, which makes for a lighter hull structure as well as saving chain plates,  shrouds, turnbuckles and other fittings.

There are already many boats sailing out there with free standing masts such as the Superyacht "Black Pearl" that has three 64 meter free standing masts and the "Dwinger" with its 63 meters long free standing rotating mast.

In order to be efficient in almost all wind directions, the wing-sail should be able to freely rotate into the wind and maintain it's 0°-10° angle of attack. A free standing rotating mast is the perfect solution.

Omer wing-sail design

​Omer wing-sail is based on a rotating A frame mast, that supports both sides of the wing, having an accurate wing cross section as well as high moment of inertia. 

The wing is made of three different sails: two main sails and one U shape leading edge sail. All three sails are sliding independently up and down the mast. When all three sails are hoisted, we get a wing that one can reef and drop down like any other conventional sail. 

With the same sails area, we get a 10%-15% faster boat while pointing higher. 

Main design differences between America's cup wing and Omer Wing-sail 

Omer Wing-Sail cross section

AC 40 wing and jib cross section

37' Omer Wing Sail Cruiser

37' omer wing sail racing (optional), america's cup ac40, patents granted: .

US 6863008, 7603958, 8281727

EU 1373064, 2404820

NZ 529216, 586805, 593939

AU 2002236181, 2008344923

SA 2010/04809

OMER Wing Sail Ltd. 

23 Hohit St. Ramat Hasharon,

Israel, 47226

Tel: +972-3-5401675  

Mobile: +972-54-4277617

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Inflated Wing Sails

La voile-aile gonflable, une aile souple, + simple + performante + user friendly, inflated wing sails (iws), laurent de kalbermatten, aviator and iws creator, edouard kessi, sailor and iws creator, based on paragliders and on inflatable aircrafts.

• A double skin forming a symetrical airfoil
• Fans placed inside the leading edge, stabilizing the sail’s shape for every wind conditions
• Free-standing and retractable mast located at the airfoil’s aerodynamic center

The IWS for yachts:

A soft and groundbreaking wing, the advantages.

• The sail flies vertically
• The NACA airfoil has been studied to develop a high driving force for a low righting moment
• Using a symetric airfoil allows to tack from one side to another without having to trim the sail shape
• The symetric airfoil is balanced and place itself in the best position to maximise the driving force
• The aerodynamic center stays stable in every wind condition
• This kind of sail could easily be driven by an automatic system

reduces effort on the boat:

• Shape control using the internal pressure
• no local stress
• better aging
• The wing flies vertically and does not create local stress inside the membrane (light sail cloth used for both ribs and the fairing)
• Little heel angle upwind
• Perfect for gigantic sails such as superyachts
• Free-standing, retractable and light mast hidden inside the wing
• Less leeway control needed, lighter keel and boat reinforcements
• A refined deck free of any hardware

IWS behaves like a muscle,

Stabilized by high internal pressure.

• No flapping
• No dynamic stress
• Spectacular absorption of the pitching effect
• Wing twist controlled by internal pressure

IWS sailplan

Is balanced around the mast:.

• No compression forces in the rigging which allows the use of a retractable mast
• No leech tension. The sheet is only used to adjust the wing in its best  angle
• The free-standing rigging allows gybing with the wing going forward around the mast, which makes the manœuvre a lot easier

IWS controls the sail area

By mast height:.

• Mast and sail expension varies according to the desired sail area
• Dropping the IWS is made by deflating the wing and retracting the mast
• The light boom, called “Nest” ® , is integrated inside the wing base and receives the part of the sail that has been dropped and deflated
• Being able to retract the mast allows a huge decrease in drag and pitch forces during motoring or while at the dock

is ideal for:

• Cruising Yachts purified from deck hardware and easier to sail.This type of rigging offers a brand new yachting philosophy
• Huge sails for passenger or cargo ships. With IWS, there is no more stress inside the sail cloth, the rig or the ship structure. This system would allow sail propulsion for this kind of vessel

the history

• prototype created using a Laser dinghy.
• International patent application.
• Comparison between a normal Laser dinghy and one with the IWS system.
• Performances and advantages validated.
• To analyse all the advantages of the IWS system, a 42m² wing has been built for a 5,5m one design boat. The retractable mast made out of 5 sections deploys up to 13m using a pneumatic system
• Test period is finished. The boat sails on lake Geneva and is at your disposal for sea trials
• Our experience aquired on the IWS proved that this system is very simple, efficient and user friendly