Sailing forward in three dimensions

The sails aboard today’s VO70 boats are a far cry from the traditional woven textiles of yesteryear. Sails of woven fiber – both natural and synthetic – had many disadvangates. They suffered from stretch, tearing, loss of shape, abrasion, rot and degradation. Today, modern materials and construction have solved these problems while also accomplishing huge gains in performance.

So exactly what types of innovations are impacting the overall rig and sail solutions for the upcoming Volvo Ocean Race?

3DL is everyones’ choice

Once again, the competitors have opted for Three-Dimensional Lamination (3DL) sail construction. This high-end sail-making technology originated in the early 1990s and is being continually evolved and perfected each year. Preferred by racers at many levels, and on many types of boats, 3DL technology has become a specialty of North Sails. As evidence of their expertise, the firm will supply all of the race entrants.
“We don’t have an exclusive relationship with the Volvo Ocean Race,” notes Steve Calder, a sail designer for North Sails and former Olympian. “But you could say that we’ve garnered a level of design  that other teams believe they need in order to be competitive.”

Calder, who’s the point man for all sail design and modeling work with the Ericsson Racing Team, works in close cooperation with team members Martin Oliver, the team’s sail maker, and Tony Mutter on the international crew with the on board sail wardrobe as his specific area of responsibility. Together, they formulate ideas and perform crucial hands-on adjustments in order to get the boats, rigs and sail inventories harmonized. This fine-tuning is performed near the Team’s base in Lanzarote. “We have a repair facility and a loft where we can take out the luffs and perform re-cutting as necessary,” Calder explains.

Start with software. Add mesh, glue, film and heat.

A 3DL sail begins life on-screen as it is takes shape in a computer-aided design (CAD) program. Then a complex puzzle of pieces are cut and laid into place on a sophisticated adjustable mold to give the sail its precise form. Strength and stability are created by laminating net-like scrims of super-strong Kevlar fibers, similar to those used in bullet-proof vests.

These scrims are oriented along the various directions of force and layers of smooth clear mylar are sandwiched onto both sides of the sail. Finally, this laminate “stack” is fused with special adhesives and heat-cured for maximum bonding. After the sail is sufficiently cooked, it’s finished with a variety of details such as batten pockets, corner reinforcements and rings. The result is an extremely light and strong composite sail with a glassy-smooth surface and zero wind porosity.

3DL sails have proven to not only hold together, they also offer exceptional shape retention in spite of the brutal conditions and hard handling on each race leg. Performance gains come from shape retension over a long duration of time.  This fact set’s 3DL sails apart from conventional sail construction.

What advances are on the way?

”For the 3DL sails, we’re experimenting with different films to enhance the durability and mileage in terms of maintaining good shape and performance over time,” says Calder. ”Presently the sails stay together well, we’re just working on how to do this better.”
The quest for the latest super fiber is always a hot topic in the world of sailmaking. The newest contender, known as PBO, is ten times stronger than steel and significantly lighter. However PBO will not be allowed in sail construction for the coming race, although it is permitted in certain parts of the rig.

Carbon fiber, the same material used in VO70 hulls, has proven to be an excellent sail-laminate. However, it is unsuitable for off-shore use because the carbon is electrically conductive and interferes with communications, navigation and radar systems.

Another promising breakthrough area is Cuben fiber. Cuben is a multi-directional Spectra laminate that uses minimal adhesives and is incredibly light. Cuben technology is now owned by North Sails and is undergoing extensive development. Steve points out that “some Cuben technology is being integrated into the 3DL process, such as finishing details, and we’re seeing lots of potential in this and future trickle-down benefits.” For off-wind work, the reaching and running sail inventory on the VO 70s that was previously dominated by nylon and light spectra cloths will now be using more Cuben as well as some 3DL sails.

Making a big leap in performance

“Looking ahead, I think the next move may be to rigid sails on the high-stability boats like VO70s and multihulls. Strategically, we’re seeing the ability to forecast weather and skirt weather patterns and this makes up a lot of what is interesting in a technical sense. The big question is: How do we make the next five- to six-knot jump in performance? If the next America’s Cup doesn’t get shut down I think we may see four- and five- component wing sails and hard sail surfaces in a future AC race.”

All images and photos: North Sails