May 4, 1998 Design News
Race on the high seas
Think a 500-mile car race
is tough? Try a 31,000-nautical-mile ocean race. That's
the distance for the Whitbread Round the World Race,
and it poses several engineering challenges. Here's
the technical detail.
Caitlin Kelly, Contributing Writer
Auckland, New Zealand--The Whitbread Round the World
Race (WRTR) is considered the Formula One of yacht racing,
the toughest, longest, most expensive and most dangerous
event of its kind. The key to victory: an experienced
crew backed up by state-of-the-art engineering.
This year's WRTR, which ends May 24, is the longest
ever held, nine months and nine legs. There are also
nine entries, two of them American--Chessie Racing and
Toshiba. The race started last September in Southampton,
England. Before it ends, there will be stopovers in
Cape Town, South Africa; Fremantle and Sydney, Australia;
Auckland, New Zealand; Sao Sebastiao, Brazil; Ft. Lauderdale;
Annapolis; and LaRochelle, France before racers sprint
back to the starting line.
Held every four years since 1973, the race covers 31,600
nautical miles. The fleet has two to four weeks in each
port to recover, repair their vessels, and re-start.
It costs an average of $6 to 12 million just to play
in this league: $2 million for the custom-designed boat,
$1 to $1.5 million for custom-made sails, $1 million
for logistics, $250,000 for running rigging (lines that
control the sails), $250,000 for standing rigging (what
the sails attach to), and $5 million for salaries. The
entry fee alone is $560,000.
The Whitbread is tough on the crew, but equally punishing
on the boats. The engineers who designed the boats,
sails, rigging, and computer systems had to make them
as fast, light, strong--and competitive--as possible.
The materials and equipment, whether DuPont's Kevlarr
aramid fiber used for the hulls or titanium fittings
high atop the mast, faced conditions from 115F heat
and high humidity off the Azores to freezing condensation
in the Tasman Sea.
Designing and racing a Whitbread 60 involves the materials
and design skills of dozens of people, literally, around
the globe: sailmakers in the United States; rigging
manufacturers in Auckland, New Zealand; software designers
in France; keyboard manufacturers in England.
This year, for the first time, every boat was the same
design: a Whitbread 60 (W60) designed by the legendary
Bruce Farr, of Annapolis, MD. But, a new feature helped
to make this race the fastest ever: The 29,700-lbs W60
uses water for ballast and a generator to pump 2,500
lb of water from one side of the boat to the other,
as needed. The flexible-impeller pumps produce a flow
of about 630l per minute. The system allows skippers
to drive their boats harder and longer upwind, which
placed new and unprecedented strains on the materials
The water-ballast-and-generator system also allows
for increased sail area, allowing W60s to go much faster
than their predecessors. Under Whitbread rules, each
boat can carry a maximum of 34,382 sq ft of sail area,
combining jib, main, and spinnaker. Top boat speeds
can reach 30 knots, equivalent to 35 mph on land. Pushing
the envelope damaged many boats this time around.
Here are some specifics of the engineering behind the
boats in this year's race.
Boat materials. All Whitbread 60s
are essentially the same: Each syndicate bought Farr's
blueprints, then used by boatyards around the world.
The materials for each boat, Kevlar skin laminates over
a rigid PVC foam core, are pretty much the same. Once
the race has begun, only the smallest, most crucial
changes or repairs are allowed--so that every design
decision must be carefully considered, planned, and
budgeted for months, even years, in advance of that
first starting gun.
Innovation Kvaerner, an entry sponsored by a Norwegian
shipping manufacturer, was determined to go as light
as possible. In their relentless quest to shave off
a mere 200 kgs, designers used aluminum alloy bolts
instead of steel, where possible, and composites wherever
practical. The bunk frames, normally built of aluminum,
were made instead of PVC pipe and also used to transport
the engine exhaust.
For Chessie, an American entry, engineers designed
the hull and deck to incorporate a prepreg construction
technique in which a foam core is sandwiched between
two skins of Kevlar fabric that has been impregnated
with epoxy resin. They did the sandwiching under vacuum
pressure inside a house-sized oven at a temperature
of 80C, tough enough to withstand the tremendous forces
of surfing the Southern Ocean at 30 knots.
Chessie's deck mold, 20 x 5.3m wide, took three weeks
to build. Next, the boat builders laid out the first
Kevlar skins by alternating layers of fabric across
the mold and along its length. In some areas, they used
as many as 10 layers. The Kevlar consists of unidirectional
aramid fibers to minimize stretching, explains Bryan
Fishback, Chessie's shore manager.
is key because any energy from the waves is transmitted
to the boat," he says. The prepreg is key to making
the hull as stiff as possible. Under Whitbread rules,
certain materials--such as Nomex foam--are forbidden
to save money.
The meat of the sandwich skin is a PVC foam core, which
comes in large sheets cut and fit over the top of the
Kevlar skin. Once complete, the skin, core, and mold
are put in the oven and baked overnight. The frames
of the mold are cut out of plywood using a laser, then
covered with thin strips of wood veneer to form the
outer skin of the mold into which the first Kevlar layer
Using technology learned from the aerospace industry,
the boat builders placed the deck and mold into a gigantic
plastic bag, which they connected to a powerful vacuum
pump that compressed the Kevlar fibers, epoxy resin,
and foam core into one solid piece. The boat-in-a-bag
was put into the oven and cooked overnight at 90C.
The finished hull and deck, polished to a gleaming
finish to ensure the fastest boat speed possible, was
then fitted with all the deck hardware, electronics,
plumbing and engine gear necessary.
Chessie's design, Fishback adds, was typical of the
W60s, which all went for minimum girth and maximum length.
"The narrower, the faster, but as you go narrower
you lose stability," he says.
Innovation Kvaerner made its boat out of Twaron, made
by Dutch firm Akzo, instead of Kevlar. The decision
to make its own pre-preg, in effect, was to keep tighter
control over the materials, says skipper Knut Frostad.
Engineers also chose light carbon fiber for the rudder,
allowing it to be even thinner and narrower, offering
less drag in the water. Whenever possible, Kvaerner
substituted fiberglass and Kevlar for aluminum and steel
to save weight.
Sails and masts. The W60s are all
custom designed, each tweaked a little differently.
Under race rules, each yacht can carry up to 17 sails,
designed to accommodate every possible wind, from no
air to 46-knot thunderstorms. The sails are also custom-designed,
molded, laminated sandwiches of composite fibers like
DuPont's Mylar polyester film, Kevlar, and AlliedSignal's
Spectra Ultra-high Molecular Weight Polyethylene. The
rigging, lines, wires, winches, and other equipment
that raise, lower, and adjust the sails, add another
set of things that can break or malfunction--and often
Paul Cayard, the skipper of EF Language, a Swedish
entry, commissioned a new, secret "monster"
sail, a heavy, huge masthead genoa. The sail kept Cayard
and his crew in the lead throughout much of the race,
but, thanks to its size and shape, it also put extraordinary--and
unanticipated--pressure on the W60's rigs. Throughout
the race, competing skippers scrambling to keep pace
with Cayard by using the sail without pre-race testing
and fine-tuning, found their rigs in jeopardy.
Masts consist of aluminum--6061T6 grade for extrusions,
manufactured in Australia by Capral in Sydney. The boat's
fittings are made of titanium, 6AL-4V, and high-tensile
stainless steel, 17-4PH, both made by Supra Alloys in
Camarillo, CA. The rod rigging is made of a stainless
alloy, Nitronic 50, made by Navtec, of Guilford, CT
and Riggarna, a British company with U.S. offices in
Portsmouth, RI. The boat's running backs, wires that
maintain rig tension from the mast to the rear of the
boat, are made of Kevlar, manufactured by DuPont, while
the halyards, lines that raise and lower the sails,
are made of Spectra or Vectran.
The aluminum mast on the W60 consists of four curved
pieces that combine to form the exterior of the 85-ft-high
structure. The only way to strengthen that original
design is by adding an extra layer of aluminum atop
the existing layers. The top of Chessie's mast, designed
only to support the loads created by a standard spinnaker
(a balloon-shaped sail), was starting to buckle under
the added load created by this new headsail.
"We have to reinforce the mast by adding doubler
plates," explained Chessie crew member Paul Van
Dyke during the boats' January stopover in Auckland,
New Zealand. "Everyone else is patching theirs
up." So concerned about the strain created by the
sail, fellow Chessie crew member and sailmaker Greg
Gendell predicted on ESPN that it would literally bring
a rig down. "The real concern is safety,"
says Van Dyke. In the middle of the Southern Ocean,
the 12 women who crew aboard one entry saw their entire
Rigging. A yacht without rigging is
one slow boat, as EF Education learned when its rig
literally fell apart mid-February in the freezing Southern
Ocean, 1,000 miles off Cape Horn, with not even enough
fuel to get back to land. Innovation Kvaerner had barely
begun the third leg, from Fremantle to Sydney, when
the base of its aluminum mast began to compress and
buckle. If it had continued, the entire rig, which supports
all the sails, could have collapsed. The solution: A