Changes in Racing Sails and Sailmaking
Changes in Racing Sails and Sailmaking
Racing sails made of laminated materials have been the choice
of leading-edge racers for nearly a quarter century. These sails,
assembled from panels built of high-strength fibers sandwiched within
plastic film, have continued to evolve, and the recent trend has been
to design the sail first, then make each section of laminate, or the
entire sail, with the expected loads of the sail in mind. In this area,
North Sails' 3DL process is the clear market leader among bigger boats.
For many sailmakers, existing patents have slowed development of
customized lamination for these newer "membrane" sails (sometimes
called "load-path" or "string" sails); but with the nine-year Sobstad
vs. North lawsuit settled (in 2001) and relevant patents due to expire
soon, there's been a spate of manufacturing news.
Last winter the industry's biggest supplier of sailcloth and laminates,
Dimension-Polyant, bought the Fraser-Doyle production facility in
Australia where Doyle D4 sails are made. D-P has cloth-weaving
factories in Germany and production laminators in the United States,
but the D4 process gives them the capability of making extra-wide
sections of laminate, produced to any designer's custom specifications.
"To maintain our level in the market," says D-P USA's president, John
Gluek, "it became apparent that membrane technology was a direction we
had to take." D-P can now deliver custom sections, assembled, to any
sailmakers' specs, including Doyle's. "It's another way for us to
provide cloth," says Gluek. "The sailmaker will send in his designs,
and have the selection of the yarn layout or type of fiber he wants."
Gluek expects D-P will add production facilities elsewhere in the world
within a couple years.
Several other sailmakers are developing their own processes of making
membrane sails more directly from raw materials. More than a year ago,
UK Sailmakers, makers of the distinctive Tape Drive sails, began
selling Ultra, a new kind of sail based on similar principles. More
recently, Ullman Sails International and the Quantum Sail Design Group
have announced new, unique approaches based on offshore manufacturing.
And North Sails hasn't been idle, continuing to invest heavily in
quality control and R&D to refine production at its 3DL plant in
Minden, Nev., and expand 3DL production of smaller sails with
rotary-molding machines.
Before D-P's acquisition, any D4 sails in this country had Doyle logos.
Sailmaker Bob Fraser, of Australia, developed the process during the
'90s and made a deal with Robbie Doyle, who wanted to start selling a
membrane-type sail. Doyle started slowly, with a sail on his own boat
in 1999, but quickly saw the value in the sails. "Every fiber is put
there for a reason and goes right to the load source; then you
distribute that fiber into the sail exactly where you want," he says.
"Fibers are employed much more efficiently compared to paneled sails."
D-P's Gluek says the benefit is in the flexibility of working in wide
sections and being able to vary fiber amounts to disperse loads more
effectively. Essentially, flat sections are laid with computer-designed
and -laid arrays of fibers and then laminated under heavy pressure
(over 70 psi). "The advantage is light weight," says Doyle. More
pressure means less glue, he says, and a lighter laminate.
D-P is producing D4 under license to Elvström/Sobstad, which holds
patents filed in the '80s by Peter Conrad at Sobstad Corp. Conrad's own
membrane-style Genesis sails have gained fresh momentum since Sobstad
and Elvström merged two years ago. Genesis sails now have seams and
yarns lined up with the loads the designers anticipate. "There's no
struggle," Conrad says. "The panel junctures in the sails-the seams-are
perfectly lined up with the load forces. No yarn crosses any panel in
the sail. If you want to build a three-dimensional context to the sail,
you do it by altering the panel junctures."
With production in China, there are now two types of Genesis racing
sails: Lightwave, the grand-prix version, for lighter breezes; and
Platinum, constructed the same way, but with an inner layer of
taffeta for strength and durability with only a slight weight and
thickness gain. Genesis sails use either Pentex yarn, at the low end,
or Vectran, which Conrad believes is better than carbon because it's
impervious to damage from flexing and creeping.
Another earlier developer of membrane sails is UK Sailmakers; its Tape
Drive sails are made of film with horizontal, shaped panels, reinforced
by high-strength tapes. These sails have been through several
evolutions over the last 17 years since UK bought Horizon Sails in 1987
and took on the technology. Both Tape Drive and Ultra, UK's new
product, are pure examples of load-path construction, with separate
materials used to provide the sail's structure and its surface. The
development of Ultra, which meant shifting from tapes to using fibers,
laid in similar patterns, was easy in theory, but a challenge in
practice. Butch Ulmer, UK International's president, says, "The old
adage that this venture would take twice as long and cost twice as much
certainly proved to be the case, but we continue to improve the product
and the process."
Ultra sails begin with rectangular film sections, tacked together and
laid flat on a vacuum table. Fibers pre-impregnated with adhesive are
then laid from corner to corner on the film by a giant
computer-controlled X/Y plotter. "We've designed the yarn layout and
yarn content," says Ulmer. "We lay down 12 yarns at a time with some
heat so it sets off the adhesive, and then put down a scrim on top."
That's followed by film with the adhesive side down and a vacuum-bag
lamination. Ulmer describes drawing the broadseamcurves on the sail,
then cutting it into sections and reassembling it as a shaped sail
using an ultrasonic machine and expensive glue. "The ultrasonic kicks
the glue and doesn't deform the Mylar," he says. Completed skins are
sent to lofts for finishing.UK continues to sell both Tape Drive and
Ultra sails, and both are licensed under patents first owned by
Sobstad, now by North under the lawsuit settlement terms.
Nearly ready for prime time are Ullman Sailmakers' membrane sails,
which will be built in China and are as yet unnamed. They're basic
"string sails," says Dave Ullman, made with carbon fibers, and shaped
traditionally with transverse panels. " Fibers are laid on panels at a
laminator to Ullman design specs- "Commercially it's the only way to do
it," says Ullman. "Laying it out as one and then cutting them like UK
[Ultra] does takes forever." As described by Ullman, first a section of
pre-preg Mylar is laid out and then carbon thread is laid down. The
carbon thread isn't pre-preg, he emphasizes: "Pre-preg carbon gets too
brittle and you can't fold it, because the carbon breaks. When carbon
is soft and laid on, it won't break. Then it becomes the most durable
of all the products." Ullman's sails are being built under an
arrangement with the Genesis patent holder Elvström/Sobstad.
While others focus on load paths in their membrane sails, Quantum Sail
Design Group is taking a different tack with its Fusion M "Smart Sail"
Technology. Larry Leonard, Quantum's president, says flatly, "They're
not load-path sails." Tested on J/29s and a Farr 52, the sails
have a computer-designed yarn layout based on the assumption that loads
are multi-directional and that load paths change with trim and
windspeed. The sails have more fiber content than most load-path sails,
Leonard says, and provide significant advantages relative to North's
3DL.
The sails have fibers where you would expect-up the leech, for
example-but most of the tack fibers radiate out to the leech and many
fibers from the clew radiate to points along the luff. Rather than
running concentrically, fibers cross frequently, creating an
interlocking structural grid that Leonard says handles shifting loads
more smoothly.
Smart Sails are laid out in a new facility in Malaysia, with arrays of
fibers on standard 54- or 60-inch Mylar panels, which are
pre-impregnated with adhesive. Dry aramid, carbon, or other fibers are
laid down on the sticky Mylar, with tension, by a computer-controlled
plotter in groups, up to 12 at a time; these panels are then laminated
individually at high pressure, trimmed for traditional broad-seaming,
and then assembled as horizontal panels with Quantum's seam adhesive.
Because of the quality of laminate, says Leonard, the sails are
produced at a competitive weight, with more shape-holding fiber than
competitors' sails, or can be lighter with similar fiber content.
North began 3DL production in 1992,
building full-sized sails out of raw materials on adjustable molds to a
designed shape. Tom Whidden, president of the North Marine Group,
acknowledges improvements in technology made by competitors, but
believes the 3DL process remains superior and distinct: "There are
still only two technologies-making paneled sails, shaped with
broad-seaming, and making a sail that's molded, which is 3DL." Whidden
emphasizes the smoothness of 3DL sails, which conform to the mold's
shape as the sails are laminated at relatively high heat.
After the sail is built on a mold, Whidden says, 3DL's Mylar sections
are there for only two purposes-to keep the wind from blowing through
the shape created, and to keep the load-bearing fibers aligned with the
paths of the loads determined by the designer.
North's rivals say that the edges of the Mylar panels are cut on a
curve to match the shape of the mold, making the sails no different
from others except that they're laminated atop a three-dimensional work
bench, i.e. the mold. It's true that North's panels are cut on a curve
to lie smoothly on top of the mold. After being cut, the pieces are
butted against each other and taped with a wide swath of
cellophane-type tape before load-bearing fibers and a tear-preventing
scrim (also pre-shaped) are laid down. But then, subjected to the
amount of heat you might cook a meal at, the Mylar layers visibly
smooth out against the mold (see photo above). "The thermoforming
brittles the Mylar a little bit,"says North VP of manufacturing, John
Welch, "but within its working range. It also forms the Mylar around
the fibers to eliminate voids."
North has 12 years of development into its expensive bet that this
process creates a superior sail, and continues to refine its design and
production. During the last America's Cup, North blind-tested 27 types
of carbon for use in sails. It has recently rebuilt nine of its 11
molds to create a smoother, more accurate and durable mold surface. And
each shipment of adhesive or other raw material is tested and samples
preserved for analysis if a laminate problem occurs in that batch of
sails. In another move made not long ago to improve laminate
durability, North switched from using faster infrared heating to a
slower conductive heating of its laminates.
But the full-sized molds have their limitations. Currently, the
facility operates three shifts, 24/7. For smaller sails, a new rotary
molding machine promises greater speed and efficiency. The drum of that
machine, introduced in Toronto two years ago, changes shape so that the
Mylar film and high-strength fibers fed onto it are laminated in a
three-dimensional shape. When the raw materials come off the other side
of the drum they comprise the entire membrane of a laminated sail. The
first machine, now retired, could make sails with a foot length of up
to 13 feet. The new RM12 machine is 40 feet wide and should be
operational by summer. The million-dollar question is how bullet-proof
it can be. If one part malfunctions, production stops.
North's competitors believe their new processes will provide lighter,
faster sails at similar or lower prices. They believe that building on
molds limits the quality and durability of North's lamination, and
makes it stiffer and often heavier. North counters that only their
sails are built exactly to their three-dimensional shape and that
they're the smoothest shapes because there are no junctions caused by
seams between flat panels.
One thing most sailmakers agree on is that membrane sails continue to
improve to the benefit of racers and, with protective taffetas applied,
even cruisers. Most sailmakers also now think that a mix of carbon and
aramid fibers is superior to and lasts longer than aramid alone. Dacron
will remain a common choice, but laminates are now making their way in
some applications into classes such as J/105s, Melges 24s, and J/24s.
Sailmakers who previously might've discouraged laminate sails on
smaller PHRF boats now not only report performance advantages but
confidence that the newer sails can provide good value.
One top sailmaker that hasn't taken the plunge
yet is Halsey Lidgard; sometime next year they plan to begin selling a
product they call "thread-align technology" on a limited basis. Andy
Halsey says their product will be laminated and have seams, but will be
shaped by more than just broadseaming. "We're a little more cautious
about getting to market," he says. "There are still patent issues and
people who have rushed them; it's not long until the patents disappear.
Our timing will coincide with that."
Several sailmakers, including Halsey, also continue making sails of
that mystery material, Cuben Fiber. Developed for Bill Koch's America3
campaign in 1992 by Heiner Meldner, a nuclear weapons physicist, and
R.J. Downs, an aerospace composite engineer, Cuben Fiber is the pricey
choice of hot racers and mega-multihulls such as Cheyenne and Geronimo.
Downs, the company president, says they do the opposite of what
everybody else does. Echoing Quantum's Leonard, Downs argues against
the idea of load-path sails. He says load paths "change continuously as
you trim" and when you reef the sail. The Cuben Fiber process takes
fibers and reduces them, says Downs, to "monofilaments in multi-layered
films, each a thousandth of an inch thick. We turn it into a very thin,
uniformly distributed tape. We layer those tapes, each with all its
fibers oriented in one direction, and put them in different
orientations." Lamination then takes place under pressure in an
autoclave.
Limited production capacity and high prices have prevented widespread
use of Cuben Fiber, but Downs says the price is now only $13 per
yard-still $4/yard higher than anything else-but cheap enough to be
showing up on top 40- and 50-footers.
Manufacturing of sails is changing-and seems to do so weekly. We agree,
as Peter Conrad says, that it's disappointing sailmakers haven't found
the ability in centralized manufacturing to offer significantly lower
prices. But if, as most sailmakers indicate, newer-style membrane sails
truly offer weight and shape-holding improvements, with multi-season
durability, those of you on the fence may find yourself soon making the
leap.
