BELOW the SURFACE: The Materials that Make Kiteboarding Possible
By Paul Lang
Originally Published int the April 2009 Issue of The Kiteboarder Magazine
When asked what properties materials used for kiteboarding equipment should have, Tony Logosz from Slingshot replied, “The materials have to be light, strong, UV resistant, impermeable, permeable, durable, compactable, low stretch, elastic, stiff, soft, airtight, breathable, inflexible, flexible, supple, watertight, waterproof, tough, stable, and so on.” That is a long list of demands for the materials that make up the seemingly simple equipment we use. Without the modern materials that can provide the traits above, the sport of kiteboarding wouldn’t be able to exist. Kites and boards must give us the performance we want, while being strong enough to stand up to the abuse that the average rider puts their gear through. A mix of materials that includes polyester, carbon fiber, epoxy, and various foams and woods gives designers the tools they need to create gear that works for riders of all levels.
What are Kites Made Of?
What are designers looking for in materials for kites? “I am always chasing materials which are stable, lightweight, and durable. There is a fine line here. Kites really need to be light to perform well, but they are exposed to an incredible amount of abuse by your average consumer. The lighter the material, in most cases the less durable and stable they are. This not only creates potential durability issues, but this also makes the kite design challenging as well,” said Pat Goodman from Cabrinha. Damien Giradin from Naish said, “For the canopy there are a few parameters that are really important: rigidity, porosity, resistance to abrasion, and the most important is the ability to keep these characteristics over time and when wet. For the leading edge and ribs, rigidity and stability are the two most important.” Julien Fillion at Liquid Force looks for “Resistance to abrasion, stiffness, good UV resistance, and, most importantly, a consistent porosity.” Caution’s Poul Schiebel said, “Overall, you try to avoid too much stretch,” and Raphael Salles from F-One looks for materials that are “Light, strong, and durable. Light because a kite has to fly so the weight is important and strong because the kites are under so much stress. They hit the water hard, they fall in waves, and they wait for you on the beach in full wind, sun, and sand. They also have inflated parts that are trying to explode!” With all of those demands, there is currently just one material that is almost exclusively used to build kites.
Polyester is the main material used to make kiteboarding kites. The creation of polyester is a multi-step process: First is the polymerization of terephthalic acid and ethylene glycol to make a polymer chip, which is then melted, spun, drawn, and wound into a fiber. Both the leading edge and canopy are made from this material (some refer to the leading edge fabric as Dacron, which is a trade name for polyester). The polyester fibers are woven into a cloth and then stabilized with a resin. This resin makes the fabric more water resistant, less porous (so air doesn’t easily pass through), and helps to control the bias elongation, which is the stretch you get when you pull on a cloth at a 45º angle to the thread orientation.
Teijin Fibers, based in Japan, supplies many of the kiteboarding manufacturers with the polyester cloth to build kites. Many riders mistakenly believe that their kite’s canopy is made from rip-stop nylon. According to Shuhei Sonekatsu of Teijin, polyester is a much better material for kiteboarding because it has much higher UV resistance and less stretch than nylon. However, polyester is easily torn when compared with nylon. Teijin’s canopy fabric, known as T9600, has become very popular with kiteboarding manufacturers because they have been able to overcome this weakness by developing a special type of high tenacity polyester yarn.
The kite companies are very secretive about what other products they have been testing, but some were willing to talk about what they’ve tried. While many manufacturers admitted that they have experimented with other fabrics for kite construction, Best is the only company currently using something significantly different from the rest. Best uses Cuben Fiber for the leading edge and ribs on some of its kites. Cuben fiber is a lightweight Dacron weave 4-directional laminate, as opposed to a woven fabric. According to designer Peter Stiewe, “Cuben Fiber provides much higher structural stability. Due to that, a reduced leading edge diameter is possible.” Other companies have tried fabrics other than polyester, but so far do not feel there are materials available that are more suited for kites.
Raphael Salles from F-One said, “We once tried a reinforced Mylar, but it didn’t last for more than three months.” On the subject of more exotic fabrics, Liquid Force’s Julien Fillion said, “So far nothing has been brought up from the factories yet that can compete with the materials we currently use.” At Naish, Damien Girardin told us, “Finding new and better material is a relentless quest for us. We have tried all kinds of materials and we have rejected a lot of them so far.” Amery Bernard from Slingshot told us that companies tried a lot of different materials in the early days, but now the materials are fairly standardized: “Now that we know what kind of qualities we need out of the materials, we can look at a material’s specs and decide if its worth pursuing or not. A large part of deciding whether or not to try material has to do with cost and performance gain. The materials have to be cost effective, and if they’re not, they have to provide an even larger performance gain. The materials on the market now have become somewhat standard because of this, even though there are different grades of the same material that change performance dramatically.”
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What Are Boards Made Of?
While the majority of kites are made mostly out of one material (polyester), the materials that go into making boards are much more varied. “Each of the different materials gets used in different quantities to achieve flex, stiffness, balance, and strength. Wood increases stiffness and strength and carbon increases stiffness and reduces weight. All of these ingredients get used together to create the right flex, response, weight, and strength,” said Slingshot shaper John Doyle.
For twin tips, some manufacturers use foam cores while others use wood. “Wood cores are about the same weight as foam, but are less prone to heel dents. Also the wood has better memory and gives more pop,” said Dave Turner of Litewave Designs. Some Litewave boards are using Kopok wood for a core, which comes from a fast growing tree. On most of its boards, Cabrinha is using a Paulownia wood core, which is also a fast growing and sustainable wood. Whatever the core is, the board is then covered in fiberglass and/or carbon. Carbon and fiberglass are both available as either unidirectional or multi-directional cloths. Unidirectional cloths have the structural elements oriented in a single direction. “Strategic placement of unidirectional glass and carbon can give you stiffness in one direction,” said Dave Turner. By carefully choosing the type and thickness of the core and the placement of fiberglass and carbon, shapers can fine tune a board to have just the characteristics they are after. Twin tips also use a denser material along the rails, most often ABS plastic, to protect the rail from damage. Usually, all of these materials are placed in press that applies pressure so that all of the layers bond properly to each other.
Surfboards have just as many choices for construction as twin tips and the materials used vary widely. Some manufacturers are using more traditional surfboard construction methods, except using EPS (expanded polystyrene) foam and epoxy resins as opposed to polyurethane foam and polyethylene resins. These boards are shaped by a CNC machine and then hand finished. Other surfboards use EPS foam and a layer of high density foam just under the fiberglass. Most surfboards use fiberglass, but carbon fiber surfboards are available as well. F-One is using a layer of bamboo in their boards: “Bamboo is an incredible material regarding strength, good looks, and price, and is also environmentally responsible,” said Raphael Salles.
Liquid Force is offering a construction method known as EVF (Epoxy Vacuum Fusion) on their surfboards this year. EVF uses fiberglass cloth cut on a bias that is vacuum bagged to the foam as the epoxy cures. “It has good flex like a polyurethane board, but it’s got a much more user-friendly type of flex for kiteboarding than a molded board,” said Pat Rawson from Liquid Force. With all of these choices available in board construction, what is the best way to build a board? That is an impossible question to answer. It all boils down to how you like how a board rides. The different materials work together to create a product that works as the designer intended. Also, the shape of the board still plays a significant part in how the board rides, regardless of what the thing is made of.
What Can We Expect to See in the Future?
Kite materials may currently be fairly standardized across the industry, but that doesn’t mean that there isn’t any room for improvement in the raw material itself. Teijin is currently developing a higher tenacity and finer polyester yarn and also working on a new special finishing process to get better rip-stop performance. “Our target is double strength compared to the current quality,” said Santoshi Asaoka of Teijin. Teijin is also working on introducing recycled materials into their kite fabrics, which will lead to kites that have less of an impact on the environment while retaining all of the performance characteristics of a product that does not contain recycled materials. Also, many companies that we talked to would not tell us about what other materials they have been testing, so it’s possible that we could see new materials being used for kites.
In the near future, you can expect new materials to be introduced, but most of the development will be in how the materials will be put together. Cabrinha’s Ian Ponting told us, “We have been experimenting with many different materials and how they are applied to the boards. One of the key focal points has been to evolve the manufacturing process to better apply our shaping theories.” By developing different manufacturing methods, designers can remove some of the limitations they have on building mass produced boards, giving them more freedom to design the exact shape they want.
Whether in kites, boards, the raw materials themselves, or the processes used to put the materials together, one thing is for sure. We will continue to see new and different materials and construction techniques being used in kiteboarding gear as designers push the envelope to make the gear lighter, stronger, and higher performance than the last generation of equipment.
Originally Published int the April 2009 Issue of The Kiteboarder Magazine