The little sister of the still-to-come AC72 turned all heads during its 14-day dress rehearsal on Auckland’s Waitemata Harbour. "Tech Review" from our March 2011 issue.
Five feet longer than an Extreme 40 and with a lot more volume in its hulls in front of the mast, the AC45 delivers more performance over a wider range of wind conditions. De Ridder estimates that the new boat has a margin of 5 knots more speed “before scary things start to happen.” He’s referring to the chance of pitchpoling, something the team doesn’t want to subject the wing to, despite its robust construction.
In a move to save weight and keep it simple, there are no cockpits or openings in the hulls, other than an inspection hatch on each hull just forward of the afi crossbeam. The trampoline is set 12 to 18 inches below deck level to facilitate crew work on winches and provide more clearance under the wing.
There are just three winches each side. There are Harken 3-to-1 ratio winches for the headsail sheets, another set for the backstays and smaller 2-to-1 ratio winches for the traveler that controls the wing’s angle of attack. The wing’s camber and twist controls are mounted under its base.
There is no mainsheet, as there is no need for one. The traveler control line leads from the wing straight out to the small winches port and starboard. “We use them in high gear most of the time,” says de Ridder. “It’s very responsive and easy to do. When sailing fully loaded upwind, to easing off to nothing, it’s less than a meter of sheeting. You can go from flying a hull to splashing down in the water in an instant.”
Mike Drummond credits Dave Hubbard and his Patient Lady C-Class catamaran program in the late ’70s for the two-element wing. “It’s deceptively simple,” he says. “The biggest advantage of the wing control system is that it replicates itself on the new tack so when you tack the wing it just flops through with wind pressure and adopts the same camber on the new tack. We made no changes to the concept. For the AC45 we kept it pretty simple.”
Designed to be transported in a 40-foot container, each hull features 5-foot long bolt-on stern sections. The through-hull rudder assemblies that fit through these sections include a lower bearing in an oblong cassette that clips into a slot in the bottom of the hull and a separate upper bearing that plugs into the deck. Installing or removing the rudders takes only two or three minutes.
For launching, a substantial tower crane hoists the wing until it’s vertical, taking care to face its leading edge into the prevailing breeze. The gumboot, a wooden box fllled with water and attached to the leading edge at the foot of the mast, stabilizes the wing and ensures that it weathervanes. The boat is rolled under the wing and afier shrouds and headstay are attached, the boat is lified into the water. Straps around the hull at the forward beam pick up the load and are led though a temporary fairlead at the masthead to stabilize the wing. With a shore crew of ten, the boat goes from shed to the water in little more than half an hour.
Mast height 70’6”
DSPL 3,080 lbs.
Wing area 914 sq. ft.
Jib area 516 sq. ft.
Draft 1,345 sq. ft.
Crew weight limit 935 lbs.*
*does not include spectator position