Cuben Fiber Performance—The Best in the World  

Bill is choosy. He selects your sail's material from the world's leading manufacturers of sailcloth.  

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Raven with Cuben Fiber Sails

Cuben Fiber is even better today!
Cuben Fiber sails are now available with better UV protection and enhanced strength with carbon. Sail purchasing decisions are much easier, with the RaceSail Series and Cuben Fiber.
The RaceSail is a revolutionary new breakthrough in sail design using elliptically shaped sail panels. Cuben Fiber is the best material available today, offering the highest performance whether you race or cruise. The RaceSail in Cuben Fiber is better than the sum of the two; it is a radical new product destined to out perform all competitors. You can only order a RaceSail in Cuben Fiber from Bill. Cuben Fiber and Dacron are the best two sail material choices available today. Choose Cuben Fiber for performance and Dacron for budget considerations.

Why do you want a RaceSail in Cuben Fiber?
You will have the lightest inventory possible. You will have the fastest and most durable sails available. You will have the happiest crew you have ever seen (sail handling is easier, pitching moment is low, righting moment is high and confidence is high).

Where's the proof of success for the RaceSail in Cuben Fiber?
Bill's Cuben Fiber RaceSail main for Pamir, a Swan 55, was used at the Heineken Cup. In 30+ knots of breeze, this new main survived in race-ready condition while molded sails were self-destructing. This boat's mainsail weighs only 49 lbs. That's right! A main for a Swan 55 which weighs 49 lbs. and survived 30 + knot winds successfully.

Do you need more assurance?
Bill built two inventories of RaceSails in Cuben Fiber for Around Alone competitors, American Bob Adams and Russian Viktor Yazykov. These bluewater racers choose Cuben Fiber RaceSails because of the durability of the material when it was used on Toshiba, Dennis Conner's Whitbread entry.

Cuben Fiber is unquestionably the best material for sails ever made.

Paneled sails are proven faster than molded sails. The RaceSail is a panel sail, designed in an elliptical pattern to improve its efficiency. Paneled sails won most important classes at Key West despite the popularity of molded sails.

What's special about the RaceSail? Elliptical load carriers transfer loads from the corners (head, clew and tack) smoothly through the sail. Every panel is shaped to give you better control of the sail in different wind and sea conditions. Every seam has an efficient purpose in addition to joining material (unlike other contrived sails where seams simply join panels). Shaping is distributed across the sails to create a smoother design. Accurate adjustment at the end of the season can restore the RaceSail's shape to almost new condition based on the sail's actual hours of use.

What's special about Cuben Fiber? It is 50 % to 70% lighter than Kevlar, four times more durable than Kevlar, and lasts as long as Spectra. It substantially improves the strength to weight ratio over conventional sail fabric. A polymer matrix embeds the fiber with Allied's long chain polymer (Spectra) and is sandwiched between layers of polyester film. There are no twisted filaments to cause crimp. It is dramatically thinner than other laminates. It allows flex without losing strength. After being folded 250 times, Kevlar laminate loses 80% of its breaking strength while Cuben Fiber retains nearly 100% of its original strength. It is not effected by salt water nor does it soak up water. It has the best resistance to UV along with Dacron.

Cuben Fiber Enhancements. In 2002, carbon was added for sails designed for high level race specific sails. In 2001, a new soft hand Tedlar coating replaced the mylar outer laminate of previous Cuben Fiber. In addition, a titanium oxide treatment extends the protection of the sail from ultra violet deterioration. For more information email Bill Shore.


Cuben Fiber

Cuben Fiber is a sail fabric that is much stronger and far lighter than Kevlar with virtually no crimp and almost immeasurable creep. It is made from Aramid materials known for their UV resistance and longevity. And it's white.

What is it? Why is it?
The recent clamor over the extraordinary stretch resistant characteristics of Cuben Fiber sail material suggests something totally new to sailmaking. The truth is Cuben Fiber has been around for some time. However, through the work of Heiner Meldner and R. J. Downs, it is now available to the public.

Cuben Fiber has found a big, broad place in the market. Cuben Fiber is used in sails for Americas' Cup, Round the World Whitbread and Around Alone (BOC) as well as one designs to PHRF to IMS and bluewater cruising. It's great for spinnakers, too.

Cuben Fiber was developed for the America3 Foundation's winning Americas' Cup campaign. The story of its beginning is an interesting one.

Evolution of Cuben Fiber
The final area of investigation in America
3's road to Cup victory and the most secret part of the sail program was the development of improved sail fabric. This effort was undertaken by a team of Stanford researchers, headed by R.J. Downs, under the direction of Heiner Meldner. The early phases of development were confined to laboratories far from San Diego, but occasionally a swatch of material was run through the Inston tester at the compound and sewn into the leech of a genoa to see how it responded to the abuse of a 50-tack day.

When Cuben Fiber emerged as the final material, a small and very secret manufacturing facility in an anonymous industrial complex in Rancho Bernardo, about 30 miles outside San Diego was established. There, an eclectic group of engineers and out-of-work California surfers assembled 30' panels of the high grade Spectra sprinkled with black graphite fiber composite.

As this was the America's Cup, paranoia surrounded the operation. There were reports of mysterious cars and helicopters following personnel from the San Diego compound to this site. When the material ultimately went to sail lofts to be turned into sails, it was never out of the sight of an America3 person who gathered up all the extra material including the scraps so that no one unassociated with the A3 program could learn more about the fabric.

These sails were truly remarkable. They weighted up to 40% less than high modulus Aramid sails. The actual Cuben Fiber fabric weight was as much as 65% lighter than Aramid fabric.

New Technology and New Problems
The material was new and untried but those were not the only problems.

The biggest problem was psychological. Curiously, these are the same psychological issues customers face when purchasing Shore Sail's Cuben Fiber sails today.

When A3 set the first Cuben Fiber mainsail, the crew's reaction was "it looks hot and it sure is light, but we can't race with it because it is so untested." As time went by and experience with the material increased, the attitude changed. By the Americas' Cup finals, the sailors demanded that all the sails were built of Cuben Fiber.

Why is it called Cuben Fiber?
The first sails were constructed from Spectra and Spectra/graphite fiber composite. They were dubbed Cuben fiber by the media. This was a result of the A
3 campaign not being taken seriously as Cup contenders and being called Cubens in disdain by the other syndicates. They, of course, adopted the name, called the A3 compound the Bay of Pigs, created a burgee with a serene pig in sunglasses and thoroughly enjoyed the singularity of the identity of the sail fabric with the winning campaign.

Stronger, Lighter, Faster
Improving the sail material was seen as a real advantage over the other syndicates. Lighter weight aloft would translate into improved righting moment and reduced pitching. Sails that don't stretch translate more air force to the boat, need fewer adjustments, hold their shape and don't require recutting as often. Moreover, the IACC rule limited the total weight of crew and sails, so reducing sail weight would allow the team to carry an extra sail or two.

Additionally, a new material was needed for the IACC boat's 5,000 ft2 asymmetrical spinnakers and reachers on the zig-zag downwind course. All existing laminates, nylons and polyesters were too stretchy, too weak, too heavy, too unmanageable, or all of the above.

We decided that lighter, stronger sails were a worthy goal. Stronger, lighter, faster became our sail development team's slogan.

A three pronged approach was developed:

    1. improve the strength to weight ratio of conventional sail fabric, leading to the development of Kevlar 49, rather than Kevlar 29, and now commonly used.
    2. develop sail construction techniques that used fiber more efficiently, such as the Shore Sails/Dimensions Polyant GSX piggyback laminate.
    3. search for a new and radically improved material, which led to far greater success than imagined.

The America
3 Foundation had as its motto "talent, teamwork and technology".

Therefore, money was spent on technology, especially technology that promised competitive advantage. A technology shared with competitors was not considered an advantage so research was carried out in secret. The effort to develop superior sail material was known by the code name B Project.

Dr. Heiner Meldner, headed development of A3's keels, rudders and other special projects including B Project. Heiner subscribes to the philosophy of "need to know". Even very senior members of A3's technical team would ask him how B Project was coming in the hope of finding out what it was all about. Heiner never succumbed to such pumping.

Very early the decision was made to take advantage of the exceptional durability of Spectra and the strength of Graphite fiber.

Heiner recruited a young composites engineer named R.J. Downs to handle the day-to-day research with help from Allied Signal and Hercules Aerospace. They started producing sample materials which were tested on the same equipment using the same protocols used to test conventional sail fabrics. The tests were encouraging. Next, large panels were tested in the leech area of full size genoas. These were the first sails ever to use carbon as the primary load carrying fiber while Spectra was present to add strength and act as a backup for a potential carbon break.

Within a few months, it was apparent we had a winning concept. Samples were approximately twice as strong for their weight as the most advanced of our commercial sail fabrics. Bill Koch, and America
3 Executive Vice President Vincent Moeyersoms, gave approval to begin production of "Cuben Fiber" in sufficient quantities to build sails.

Bill Shore, Heiner and R.J. developed specifications for the first material production. The communication between sailmakers and engineers was easy because the material's modulus, a property common to engineers, matched its Kevlar equivalent in deniers per inch, a concept familiar to sailmakers.

The material was laboriously hand assembled in an anonymous warehouse about 30 miles northeast of San Diego in a process more like building than weaving cloth. As the production demands increased, unemployed surfers and a handful of materials scientists augmented the team. Layers of the laminates were stacked between aluminum sheets and peal-plies, vacuum bagged and trucked across the lot to the autoclave. After a night in the oven, the stack was pealed apart and Cuben Fiber sheets were made ready for sails.

The First Sail was a Main
The first Cuben Fiber sail weighed just over 100 lbs. compared with the first A
3 Kevlar main sail which weighed over 250 lbs. When the sailors hefted the Cuben Fiber main onto their shoulders to carry it down to the boat, they refused to believe that they were carrying a main.

Even after the sail was on the boat and flying like a main sail, they refused to believe this sail could last for any length of time. A few days later, however, the sail survived several hours of thrashing around San Diego Harbor in sustained winds of 25 knots with gusts over 35.

Gradually, other Cuben Fiber sails were built. A Code 1 Genoa experienced the most abuse of any sail in our experience when Stars and Stripes and America3 each executed 80 tacks in one race. The crew was convinced that the sail was trashed, yet our onboard sail shape tracking video cameras detected no change in the sail's shape. When we cut some samples from the leech for testing, the Instron showed them to be the same as when they were new.

The Cuben sailors, like sailors everywhere, were conservative. They were well aware that the surest way to lose a race was not to finish. So, they were slow to accept the radical nature and untested performance of Cuben Fiber. As sail after sail proved its merit, the attitude changed first to grudging acceptance and eventually to addiction. By the Cup finals, A3 was using Cuben Fiber in all the upwind sails and in some spinnakers.

Seven different styles of Cuben Fiber were used. These varied in weight from .5 oz. per sailmaker's yard (36"x28.5") up to about 4.5 oz. They ranged in strength from the equivalent of 6,000 deniers per inch of Kevlar up to almost 50,000 deniers per inch. Winning sails for all conditions were built from Cuben Fiber.

What Makes Cuben Fiber So Great?
Cuben Fiber is basically a matrix of Allied's long chain polymer, Spectra 2000, sandwiched between layers Tedlar, or polyester film. For highly loaded areas of IACC sails, small ribbons of graphite fiber were embedded in a polymer matrix and combined with the Spectra body. These sails appeared lustrous silver-gray. Today's Cuben Fiber is made without the graphite and appears translucent pale milky white. It looks like waxed paper.

Conventional woven Kevlar fabric stretches at least partially because of crimp, the bending of the yarns inherent in the over and under weaving process. Even in some conventional unworn scrim laminates the individual filaments are not perfectly aligned due to the twist used to keep the yarns together for handling prior to lamination. The filaments in Cuben Fiber have neither twist nor crimp, so they do not need to straighten out before taking their full load.

A sampling of Cuben Fiber made of 2.7 oz. per sailmaker's yard requires the same load to reach 1% elongation as a 6.5 oz. Aramid or Kevlar laminate. These are truly remarkable numbers for non-graphite makeup. Advances in production at Hercules Aerospace for in-line plasma, corona and prega treatment account for the new Cuben Fiber material yielding 20% more strength to weight efficiency than the old graphite enhanced version. Spectra's well-documented longevity adds frosting the cake. It takes some imagination to contemplate materials this light and this strong that maintain their strength so long.

Conventional Spectra suffers from creep characterized by the fabric's slow continuous stretch, or growth, under load over time. New Cuben Fiber laminates are made with patented technologies using unidirectional prepregnated tapes of in-line plasma treatment fibers that are spread into mono-filament level films. This plasma pass reduces creep to levels more than acceptable.

Another important aspect of Cuben Fiber is its thickness, or really its thinness. Because it has no twisted yarns, the material is dramatically thinner than other laminates. This contributes to its ability to flex without loss of strength. After being folded 250 times, a typical aramid laminate will lose more than 80% of its breaking strength, while Cuben Fiber retains nearly 100% of its original breaking strength.

Cuben Fiber Enhancements
In 2002, carbon was added for sails designed for high level race specific sails. In 2001, a new soft hand Tedlar coating replaced the mylar outer laminate of previous Cuben Fiber. In addition, a titanium oxide treatment extends the protection of the sail from ultra violet deterioration. 

Always Top Quality Materials
Only top quality material is used. All material is tested twice, once by the producing company and a second time by Shore Sails before your sail is cut and constructed. This is your assurance that your sails will be fast and durable.

Several material choices may be available for your sail because we purchase from manufacturers worldwide. We will consider options for combining materials to achieve strength, durability, weight and cost and we make recommendations to suit your needs. Having pioneered composite sail design, Shore Sails is a leader in mixing materials to achieve lightweight and highly durable sails.

Manufacturers work with us to create material to our specifications. We work with major suppliers to advance weight reductions without sacrificing strength. Ask us about the latest developments in materials.

Bigger, Taller, Faster
The most persistent trend in sailing over the last few years has been the desire of smaller crews to sail bigger, faster boats. This means bigger, taller sail plans. While modern sail-handling hardware, from winches to furling gear, has helped to make this possible, sail inventories consisting of fewer, lighter sails contribute, as well.

Sail materials are continually changing and being improved. Each year, sail material suppliers introduce dozens of new options and improve old ones. Materials improvements translate to good news for customers because we can build stronger, lighter, more durable sails. The newest fibers, films and laminating techniques help us create lightweight and low stretch products.

Performance Cruising
Woven polyester fabrics have been well known to sailors since the 1960’s. They have many good characteristics. They are strong and stretch little for their weight. They resist abrasion well. They can be bent and folded. As offshore racers switch to other materials, the weaves and finishes of the woven polyester fabrics are becoming optimized for cruising sails, which generally means improved durability.

Woven fabrics have some limitations because of the nature of the weaving process. Tighter weaving produces a more stable matrix and, therefore, relatively low bias stretch. But tighter weaving produces more crimp in the warp threads and more stretch in that direction. Woven materials tend to be best suited to moderate-size mainsails and high-aspect jibs where the loads are reasonable and are concentrated along the leech of the sail. In cruising sails, we align the fabric's fill threads with the leech of a high-aspect ratio cross-cut panel layout to achieve a good combination of stability and durability while using cloth very efficiently for an excellent overall sail value.

Bill uses composite materials made by laminating two or more layers together. The result is a hybrid utilizing the best characteristics of each constituent component. The best composite cruising fabrics consist of a thin film layer and some type of scrim layer sandwiched between layers of tightly woven taffeta. The film supplies a base for lamination, zero porosity, and a little bias stability. The scrim provides a great deal of strength in one or more directions. The taffeta supplies abrasion and tear resistance as well as some warp and fill stretch resistance.

These materials are optimized for low warp stretch and are best used in radial construction, especially roller-furling genoas. These sails experience a wide range of loading with the loading more diffuse and less concentrated along the leech. Although radial panels use cloth less efficiently than crosscut panels, sails can be lighter and cover a wider range of conditions using a warp-efficient composite in this configuration.

Some composite materials incorporate extremely high modulus yarns in the scrim or taffeta warp to improve their strength-to-weight ratio. Additionally, some of these products resist UV degradation and breakage due to flexing. These materials are more expensive than their all-polyester counterparts, but for larger boats, they are a worthwhile investment since they weigh dramatically less than polyester sails and last longer.

As racing sail materials continues to improve, so does cruising sail fabric. New weaving techniques allow hybrid weaving with exceptional warp strength. Newer composite materials are stronger, lighter, and more durable. These improvements mean a brighter future for racing and cruising sailors. Lightweight and low stretch sails benefit the cruising sailor by filling sooner in light winds, contributing to less heeling and pitching moment when set, using less space when stowed and holding their designed shape over a greater wind range.



Choosing Sails

Contact Bill Shore

© Shore Sails International 2006
(401) 862-9608

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