Sailcloth diversityAug 31, 2016
Voyaging sailboats moving beyond Dacron
A sailmaker at a Doyle Sails loft working on a jib.
Courtesy Doyle Sailmakers
Years ago, when Dick and Ginger Stevenson bought Alchemy, their Valiant 42, the vessel came equipped with a full line of Dacron sails. These sails performed as expected, and the staysail lasted almost 15 years.
When it came time to replace them, the former full-time live-aboards bought laminate sails for the main and jib. The couple wanted to achieve a longer period of good sail shape “and that was accomplished,” Dick Stevenson said in an email from Alchemy, anchored in Galway, Ireland.
The couple, who spend six months a year aboard Alchemy are certainly not alone in their search for high-performance, reliable sails that hold their shape. For more than 50 years, Dacron has been the gold standard in cruising sails, particularly for vessels less than 45 feet. The tightly woven polyester fabric is long lasting, holds its shape reasonably well, withstands UV damage and has acceptable stretch. It’s affordable and meets the needs of most voyagers.
But the longevity and shape life of rolled laminate and custom composite sails have significantly improved in recent years, and many voyagers are giving these materials another look. Meanwhile, new materials used in woven sails are making those sails stronger and longer lasting. In other words, Dacron is slowly losing its place as the primary choice for cruising sails.
“I think a big part of it is driven by owners’ desire for greater performance from their sails and seeking out better durability, better long-term shape retention,” said Glenn Cook, head sail designer at Doyle Sailmakers.
Laminated sail material is relatively old at this point. “The technology has been around since the early 1980s,” Cook continued. “But what is different now is that glues, fibers and surface material have developed to the point that durability is greatly improved.”
According to Bill Fortenberry, cruising segment manager at North Sails, it’s not just the material a sail is constructed with, but also the method. North has used its innovative 3Di method for making racing sails for some time, but now cruisers are buying North’s 3Di sails. “A lot of our customers are moving to our 3Di Endurance cruising sails,” Fortenberry said.
And the increased number of large sailboats have special needs due to their size. According to David Flynn, director of special projects for Quantum Sails, six to eight years ago, 80-foot cruising sailboats were relatively rare, and now that market is lively.
North’s 3DL mold uses a pneumatically actuated table that assumes the shape of the desired sail. Then a computer-controlled head lays down high-strength fibers onto a mylar film.
Courtesy North Sails
“Superyachts are everywhere, and none of those boats would possibly consider using woven polyester,” Flynn said. “The loads are just too high and the demand is too high. Composites are the only way to build those sails.”
Laminates and composites
First, it helps to distinguish between laminate and composite sails. A laminate sail has several layers that are glued together with adhesives. The sail has a multilayer cross-section. A composite sail has different sections of cloth that are bonded together chemically. North, for example, uses thin, unidirectional spread filament tapes that are pre-impregnated with Thermoset adhesive. Composite sails use these types of fiber bundles rather than a woven fabric like Dacron.
Laminate sails will use cloths made from advanced polyethylene fibers such as Dyneema, Certran and others. With these fabrics, the fiber distribution is uniform along the length of the roll of material. A laminate sail will be made with layers that help handle the load distribution. These layers in a laminate sail are then glued together. Laminate sails also have UV inhibitors in the glue to help protect against UV breakdown, which can cause a sail in the tropics, for example, to delaminate.
Composites use carbon fiber and other “high-modulus” materials and aim for single-layer strength. To protect the composite, they are frequently bonded with light taffetas for durability and chafe resistance. Doyle’s custom composite line is called Stratis, while Quantum’s is known as Fusion M.
Rather than cutting and placing panels to approximate the load path on a sail, Stratis and Fusion M sails use carbon fiber, Dyneema, Spectra and other high-modulus materials along specific load paths. Every fiber is load bearing, creating a strong sail that weighs less and lasts longer.
Of course, the location of these load-bearing fibers is not the result of guesswork. Sail companies are now using sophisticated computer programs and modeling tools to custom-tailor sails to each vessel and its needs. Quantum says this technology ensures the sails last longer and are easy to trim in a wide range of conditions.
With its 3DL construction technique, North uses a pneumatically actuated table that can bend into a foil shape. “The table turns into an airplane wing,” Fortenberry said. And the sail is formed over this 3D airfoil shape. According to Fortenberry, the different process of making a composite sail using 3DL leads to a sail that is low weight and durable, especially where UV is involved. “Because we use exothermic resin rather than endothermic resin [often used for laminate sails], the composite is inert,” he said. “The heat from the sun doesn’t continue to cure the sail and lead to delamination.”
Woven sails also have gotten an upgrade in recent years. Clothmaker Dimension-Polyant’s Hydra Net fabric is just one example. The company says its Hydra Net fabric, made with polyester and advanced polyethylene fibers in the weave, is comfortable to handle and has higher flex strength, lower susceptibility to mildew and easier storage with better overall durability.
For voyagers, older style cross-cut sails are increasingly giving way to other types of construction like tri-radial.
Different sailcloths have different strengths and weaknesses and vastly different price points. But the main difference between polyester and other materials is in reduced stretch. The materials used in laminate and composite sails can stretch between five and eight times less than polyester yarn depending on the material, according to Flynn.
Laminate and composite sails also typically maintain sail shape longer than polyester fabrics, which can improve how the sail functions with self-furling systems and other components. Better sail shape also means better control and better upwind performance.
“There has been a myth that is gradually eroding on the cruising side, that somehow composites aren’t durable, or that you can’t rely on them. In 1987 that was probably true, but in 2016 some of the composites I would offer are probably more durable in some ways,” Flynn said.
At this point, laminate and composite sails have more or less proven themselves on longer boats — those over 40 or 45 feet where the loads are higher. But will these higher-end sails’ promised improvements be fully realized on smaller boats?
“And at this size the loads are less so the demands on the material are comparatively less,” Cook said. “The most common refrain from our cruising clients is that they are looking for long-term durability and the reality is that woven material and laminated material now have similar longevity. It is more a question of performance versus budget,” he continued.
With the added performance and improved durability that composite sails provide, Fortenberry says the added cost of the sails is worth it to many sailors. “Our customers are happy to pay for greater value over time.”
A typical rolled laminate sail costs about 50 percent more than a standard Dacron sail, while composite sails made from carbon fiber and other high-modulus materials can cost twice as much as Dacron.
The Stevensons had good luck with their rolled laminate sails, but there were some challenges over time.
Laminated sails are composed of various layers that are glued together.
“The downside of laminate was that water intruded between the layers, making for mostly cosmetic issues in a few spots. More important, the sail lost structural integrity at the head where it was folded when put away,” Dick said, describing the “hinging effect.”
“We had to move the sail track cars to shift the folds and also did some reinforcing. This was in its last couple of years of life when it was starting to show signs of delamination in multiple places. The shape was still good,” he continued.
Polyester and high-tech weaves
When those sails needed replacing, the couple did extensive research and chose Hydra Net radial sailcloth, a woven sail made with polyester plus other high-tech materials. “Our first order wish was for longevity in sail shape,” he said. “It was secondary but also important to return to a woven material as sails are frequently wet in our present cruising grounds and likely to be put away wet or at least damp.”
During three full seasons with the Hydra Net main, staysail and jib topsail, the couple has been pleased with them and said they still look new.
After years of sailing and experience with a wide range of sails, the Stevensons say there is no wrong decision when it comes to common sail materials. They recommend understanding the goals for the sail and factoring that into the decision.
Casey Conley is a staff writer for Ocean Navigator and editor of American Tugboat Review.