Race on the high seas

May 4, 1998 Design News

YACHT RACING

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 and equipment.

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.

"Stiffness 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 was laid.

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 do.

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 rig collapse.

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 helicop