AC72 approximate dimensions: LOA - 22.0 meters (72 feet) Beam - 14.0 meters (46 feet) Displacement - 7,000 kilograms (15,500 pounds) Wingsail area – 300 square meters (3,229 square feet)
The catamaran will be able to fly
a hull in 5 to 6 knots true windspeed. The target boatspeeds in winds under 10 knots were set at 1.2 times the true windspeed upwind and 1.6 times true windspeed downwind. High speeds are derived from
enormous power. The AC72 has a righting moment of approximately 60-ton-meters. Determining the sail plan dimensions was difficult because the boat has to be powerful in light winds and not overpowered in stronger winds.
“It’s been challenging to have the CGMW25bw 7/24/07 4:19 PM Page 1
cat fully powered-up and flying a hull in light winds, yet also able to sail in 30 knots,” Melvin said. “We put a lot of time and effort into sizing the wingsail and the platform dimensions in order to sail in that full range.” The height of the wingsail will be
approximately 40 meters (130 feet) with a maximum chord length between 10 and 11 meters (32 and 36 feet). Two options for depowering are
removable flaps on the upper leech or a removable mast tip. Both options would reduce sail and weight. With such a wide boat, additional
structure has been required to optimize the longitudinal stability of the AC72 to dampen flexing and to resist the high forestay loads. A draft of the AC72 Rule has been
completed and the final rule will be issued by September 30.
Other highlights of the new class:
• Ease of assembly: The AC72 can be assembled in two days and disassembled in one to accommodate the shipping schedule for the America’s Cup World Series events.
• Platform configuration: Either a conventional layout catamaran, one with cockpits and helmsman stations in both hulls, or teams will have an option of designing a central pod to centralize all the wing and sail- handling controls.
• Wingsail or soft sails: The AC72 class rule allows for wingsail and soft sail
options to promote racing through a broad range of conditions.
• Power source: Engines are banned but electrically driven valves to control the wingsail might be permitted.
• Rudders and daggerboards: The rule limits a maximum of four underwater appendages, two rudders and two daggerboards. To reduce costs, standardized, one- design daggerboards are being considered.
• Construction materials and methods: Limits on high-modulus carbon- fiber have been put in place for hull construction. The class rule outlines a minimum outside skin weight of 600 grams per square meter, similar to other racing boats of that size. Core materials may either be foam or honeycomb. High-modulus carbon will be allowed in the wingsail, to add stiffness and strength.
• Onboard cameramen will be carried during racing. The Golden Gate Yacht Club
www.ggyc.com/
CAPE GEORGE MARINE WORKS, INC.
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Cape George 38
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designed 28' Bristol Channel and 22' Falmouth Cutters
31' 34' 36' 38' 40.5' 45'
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www.capegeorgecutters.com
48° NORTH, OCTOBER 2010 PAGE 32
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