NOW THAT BENETEAU IS EXPERIMENTING WITH WINGSAILS, IS

Taking Wing
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as the wingsail finally come of age?
After last year’s breathtaking America’s Cup series, and the news from
boatbuilding giant Beneteau that it is
experimenting with wings as an alternative to the traditional Bermudian
sailplan on its production boats, it certainly looks that way.
Where one leads, others follow, and if Beneteau’s trials go the
way the factory expects, then cruising boats sporting one or
two elliptical wings will be a common sight in years to come.
It took the Cup to put the spotlight back on the wingsail, but
it has been around for decades in various iterations. Dennis Conner sailed the catamaran Stars & Stripes, sporting a hard wingsail, to victory in the 1988 mismatch against Sir Michael Fay’s
Kiwi challenger. Back in the early 1990s Walker Wingsail Systems
also designed and built a handful of cruising trimarans equipped
with computer-controlled hard wingsails, before technical and
legal problems—not mention a distinct lack of enthusiasm from
the sailing community—eventually ended the company’s attempts
Famed French ocean racer
Michel Desjoyeaux is at the
helm during this trial of the
Beneteau soft wing
Taking Wing
to make an impact on the market. The
execution may have been flawed, but for
many designers, engineers and sailors,
the Walker Wingsail was at least a brave
attempt to answer one question: why
do sailboats have rigs and sails that are
inherently inefficient?
BECAUSE A MAST is supported by
wires fore and aft, which make two triangles, its sails must also be triangular
in shape; and the triangle is the worst
possible planform for a sail that must
propel a boat to windward, thanks to
a phenomenon called induced drag,
which comes as a product of any surface generating lift. You don’t see many
birds or insects with triangular wings,
nor aircraft, except very high-speed
fighter planes aboard which the triangle
planform actually comes into its own at
supersonic speeds.
Worse yet, these inefficient triangles
are held aloft by a rig that’s trying to
push the mast through the bottom of
the hull while pulling the ends of the
boat up like a banana: a highly tensioned assemblage of wires, turnbuckles
and myriad other small fittings, even the
smallest and cheapest of which could
cause the whole lot to crash down on
your head should it fail. Seems crazy,
doesn’t it?
The most effective airfoil in terms
of generating lift has an elliptical or
semi-elliptical shape. Neither of these is
affected by induced drag to anywhere
near the extent of the triangle. The
heavily roached mainsails that came into
vogue on multihulls during the 1990s,
and now the trend toward squaretopped mainsails on both multis and
monos, are steps along the road to more
aerodynamically efficient—therefore
faster—sails that would also win over
the conservative cruising sailor. The
wingsail may be at the end of that road.
FIRST, THOUGH, there is a mountain of
prejudice to overcome. Show a typical
cruising sailor a photo of a wingsail on
a production boat and the reaction will
range from “That looks weird” to “Dude,
that is butt-ugly.” Most sailors raised on
bermudian rigs just can’t get their heads
around a boat that has no shrouds to
hang onto or a sail that isn’t triangular.
They certainly view hard wings with
suspicion, even after the Cup races.
Of the two types of wingsail, only the
soft wing has a chance of catching on
with mainstream sailors. If performance
is the only goal, then you can’t do better than the hard wing’s aerodynamic
efficiency. But you can’t reef it, its variable geometry is complex to control, it
is expensive to produce, and its smaller
area makes it slow downwind.
The soft wing, on the other hand, can
be reefed and stowed, can be made of
regular sailcloth, is simple to control
and easy to handle, and it is robust.
Set on a freestanding spar, it puts no
compression loads on the hull and in its
most basic form is trimmed by just one
sheet—though if the spar rotates there
must be a means of limiting its travel as
well, and a way to control the camber, or
depth, of the airfoil. On hard wings like
those of the AC boats this is achieved
by using multiple hinged vertical elements to adjust the “shape.” Most soft
wing variants can also twist in the same
manner as a conventional mainsail to
account for the differing wind direction aloft, whereas a hard wing needs a
complex array of trailing flaps to achieve
this.
Birds of a Feather
Though soft wingsails may be “new”
to most sailors, various iterations have
existed for decades. Nearly a century
ago L. Francis Herreshoff patented a rig
that had a two-ply mainsail and jib, each
with its leading edge attached to the
sides of a rotating spar. This approach
would go on to serve as a precursor to
the double-skinned variable-camber
wing, as developed by Australian company Advanced Wingsail Systems. The
AWS mast can be rotated to bend the
battens of the double-skinned mainsail,
allowing camber to be controlled either
manually or electronically. In appearance
the AWS sail is much like a conventional
bermudian rig.
ANOTHER APPROACH to wing design
is being taken by former fighter pilot Ilan
Gonen with the Omer Wing Sail, which
he’s been developing for a decade.
The Omer Wing Sail is actually three
“sails”—two panels and a fabric leading
edge for the wing—all set on a rotating
carbon fiber A-frame mast. When setting
up the rig, the two mains are hoisted up
the A-frame legs, and the leading edge
goes up tracks in front of the mast. The
angle the boom makes with the leading
edge can then be adjusted to control
camber in much the same way changing
outhaul and halyard tension does on a
conventional mainsail.
Once underway the helmsman has
just two sail controls to deal with: the
mainsheet and the hydraulic ram that
controls the boom’s angle to the leading
edge. Gonen uses an Elan 37 for a test
bed, and boat-for-boat testing has found
that despite having 15 percent less
sail area, his wingsail outperforms the
conventional rig on every point of sail
except dead downwind. A gennaker can
Far left: a view of the softfabric leading edge of
the Omer Wing Sail, and
the hydraulic ram that
changes the sail’s camber.
Left: the freestanding
balestron rig on the
schooner Matin Bleu
was the inspiration for
Beneteau’s trial wing
There have been many variations on the wingsail concept.
Here are some of them.
WALKER WINGSAIL
This 1990s British concept
was the spin-off from a failed
attempt to build wingsails for
cargo ships. Five trimarans
were built, all with rotating
hard wingsails that were computer-controlled. The public
just wasn’t ready for the idea:
John Walker was more famous
for winning a high-profile
lawsuit against British magazine Yachting World than he
was for building boats.
The structure of the
lead element of the
Beneteau wing is
straightforward
be set to improve downwind speed.
The wing’s advantages under sail
include greater efficiency not just to
windward—the wing-equipped boat
points 10 degrees or more higher—but
also on a reach, where it performs better in light air than the conventional
rig. As wind speed increases and the
wing generates more lift, the camber
can be flattened, and the boat will sail
even closer to the wind. Below about
130 degrees, the gap between the two
rigs closes until the conventional rig’s
greater sail area takes it into the lead
going dead downwind.
The reason for this increased performance is that the wing has a lower
angle of attack (a line drawn between
the leading and trailing edges of the
sail and the apparent wind direction)
than a conventional sail, and the lower
the angle of attack, the less induced
drag is generated. For example, the
angle of attack on an Omer wing is
between 0 and 10 degrees, while on
a typical conventional rig it is never
less than 15-20 degrees, and can be as
much as 90 degrees on a well-eased
headsail. This lower angle of attack
translates into less heeling moment and
more driving force.
Tacking is pretty much a
case of putting the helm over
and pushing a preset button
that changes the camber—on
hard-winged boats like the
AC45s, this is accomplished
by a crewman manually “tacking” the wing. In its present
incarnation, the Omer wing
has two reefs, which can be
managed from the cockpit.
Should the boat be overpowered by a gust, all you have
to do is let the mainsheet go
and the sail will feather; if it’s
really blowing hard, dropping
the leading edge will depower
the sail completely.
Which brings us to gybing,
which is much gentler with
a wingsail like the Omer because the leading edge projecting ahead
of the mast acts as an air brake, slowing
the speed at which the sail slams across
the boat.
UNTIL VERY RECENTLY, production
builders’ responses to the temptations
of the wingsail have been the corporate equivalent of clapping hands over
ears and saying “la la la la la” loudly.
X-WING SAIL
Want to turbocharge your
Sunfish or Laser? These snazzy little carbon fiber and Mylar
wings will get you up on the
plane in no time. They’re also
made to fit Hobie cats and tris.
OPTIMIST WITH WING
Some enterprising Kiwis
adapted the top section of the
sail from an A-class catamaran to fit this Optimist dinghy;
it proved very fast.
SOFTWING
Here is another variant on the
wing—as seen on the P-28
foiler, developed in Switzerland.
ADVANCED WING SYSTEMS
This Australian company has
developed soft wing sails for
Moths and Mini 6.5 racers,
and is working on others.
The first big boatbuilding company to
seriously investigate the virtues of the
wingsail has been Beneteau, which
over the last few years seems to have
been on a mission to reinvent the cruising sailboat.
Under the auspices of Bruno Belmont,
Beneteau’s head of product development, a soft wingsail has been installed
on a Sense 43 and sea trials are ongo-
Lift
F
Heeling Force
Main pic: Beneteau’s twoelement wing has a hinged
trailing edge; Left, from top:
the two-ply AWS mainsail;
Beneteau’s soft wing can be
dropped like a normal sail; the
Omer Wing Sail under way
WING
Driving Force
10º
30
Freestanding,
rotating carbon
fiber mast
ºA
pp
ar
en
tW
in
Sail can be made
from Dacron or
high-tech fabric
F
Lift
F Heeling Force
ag
Dr
15º
Heeling Force
d
Upper section of soft
wings can “twist”
like conventional
mainsail
BERMUDIAN
ag
Dr
20º
30
ºA
pp
ar
en
A hinged after
section allows
camber to be
changed
tW
in
Sail area
forward of
mast acts
as “a brake”
when gybing
Drag/
Heeling Force
d
F
WING
10º
Lift/Driving Force
Sail can be reefed
and stowed like a
conventional main
F
Because spar
rotates, wind
instruments
can’t be
mounted
at the
masthead
Heeling Force
90º Apparent Wind
Drag
BERMUDIAN
20º
Lift/Driving Force
90º Apparent Wind
Sail is controlled
by a single sheet
WING
º
10
Driving Force
Drag
d
tW
in
ºA
pp
ar
en
13
5
F
Lift
Heeling Force
Drag
BERMUDIAN
Heeling Force
ºA
pp
ar
en
*F = the
combined
effect of drag
and lift vector
forces
tW
in
d
Driving Force
13
5
Taking Wing
ing. The aim is eventually
LeRouge design which
WING VS SLOOP
to offer wingsail-rigged
utilizes a variant of the balHere’s how
boats as an option to conestron rig that’s commonly
Omer illustrates
the difference
ventional rigs and thereseen on model sailboats.
between wing and
by, says Belmont, attract a
Owner/skipper Guy Beaup
conventional sails.
whole new breed of sailor.
has sailed tens of thousands
At 30° to the
Belmont’s goal is
of miles under this rig, so
apparent wind, the
wing’s 10° angle of
straightforward: he wants
it is a proven concept. The
attack generates
to make sailing easier, and
only question is whether the
low drag and plenty
of lift.
thereby bring new people
wingsail in general will be
into the sport. “Sailing
With their greater a viable rig for production
angles of attack (15
suffers from the fact that
boats.
and 20° respectively)
newcomers see it as too
Noted designer Nigel
the genoa and
mainsail create
hard to learn,” he says.
Irens, who has designed
more drag and less
“We are looking at ways
both multihulls and monolift. Heeling force
is increased at the
of simplifying boats and
hulls with freestanding rigs,
expense of driving
sailing.” Bringing new
is a fan of the wingsail, but
force.
people into the game is
feels that “bizarrely, the
The wing works
of course the holy grail of
main obstacle in getting the
very well on a beam
reach because the
the sailing industry as a
rig to market might be one
lift—and therefore
whole—each year, thouof cost. When you look at a
the driving force—is
mostly directed
sands of the baby-boomconventional rig on a proforward and there is
ers who popularized the
duction boat, you’d be hard
little drag or heeling
force.
sport in the ‘70s and ‘80s
pushed to find a cheaper
are aging out, and it is not
way of spreading out the
By comparison,
the conventional
proving easy to replace
required amount of sail to
sailplan suffers
them.
drive the boat along.
because the welleased genoa does
Beneteau’s vision ex“Free-standing masts like
not work as an
tends to rethinking the
those
supporting the Matin
airfoil, and thereby
generates lots of
way other things are
Bleu rig are tapered carbon/
drag and heeling
done. What if the mainepoxy structures and findforce. The main
is still relatively
sheet and halyards were
ing ways to build such a
efficient.
led to captive winches,
spar down to a price is not
Downwind, the
and sails hoisted or
easy,” says Irens. “Building
well-eased wing,
trimmed at the push of
such a rig into a monohull or
still with a 10° angle
of attack, retains
a button? The absence
even a trimaran is relatively
its airfoil shape
of shrouds means deck
simple because the ‘bury’
and creates lift to
windward. Drag is
safety needs a fresh
between upper and lower
minimal, and most of
look—perhaps there will
bearings is substantial. But
the heeling force is
directed to windward. a free-standing mast doesn’t
be solid handrails instead
of wire guardrails, maybe
seem to be a natural opOn the same
broad reach, the
incorporated with higher
tion for a catamaran as the
conventional sails’
bulwarks. Boats may have
angle of attack is 90° depth between upper and
so instead of working lower bearings is bound to
to be designed to accept
as airfoils, all their
either a conventional or
drive is created from be limited. It has been done
drag.
freestanding rig, which
successfully in the past, but
means differences in conbuilding such a structure
struction too—a hull that doesn’t
into a production boat at the right
need to withstand the massive comprice may be challenging.”
pression loads of a bermudian rig
None of these obstacles will be
can be made lighter, which means
impossible to overcome for a deterit won’t need as much sail to drive
mined builder, as long as there is
it, which means a smaller rig, which
demand for the product. Undoubtedwon’t need much in the way of deck
ly because of the Cup, which made
gear. Beneteau’s brains trust for this
wingsails a common sight, there is
experiment includes such luminarnow more understanding of the conies as famous solo sailor Michel Descept among sailors. The weirdness
joyeaux, “who thinks we definitely
factor is wearing off. And here’s
have something,” says Belmont.
the thing: the sailors Beneteau has
The Beneteau soft wing is based
in mind for its wingsail-equipped
on the twin freestanding sails
boats won’t have any prejudices
sported by the French schooner
anyway, because they’ll be new to
Matin Bleu, an experimental Eric
the sport.
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