The AC75 combines extremely high-performance sailing and great match racing with the safety of a boat that can right itself in the event of a capsize. The ground-breaking concept is achieved through the use of twin canting T-foils, ballasted to provide righting-moment when sailing, and roll stability at low speed.
The normal sailing mode sees the leeward foil lowered to provide lift and enable foiling, with the windward foil raised out of the water to maximise the lever-arm of the ballast and reduce drag. In pre-starts and through manoeuvres, both foils can be lowered to provide extra lift and roll control, also useful in rougher sea conditions and providing a wider window for racing.
Although racing performance has been the cornerstone of the design, consideration has had to be focused on the more practical aspects of the boat in the shed and at the dock, where both foils are canted right under the hull in order to provide natural roll stability and to allow the yacht to fit into a standard marina berth.
An underlying principle has been to provide affordable and sustainable technology 'trickle down' to other sailing classes and yachts. Whilst recent America's Cup multihulls have benefitted from the power and control of rigid wing sails, there has been no transfer of this technology to the rigs of other sailing classes. In tandem with the innovations of the foiling system, Emirates Team New Zealand and Luna Rossa are investigating a number of possible innovations for the AC75's rig, with the requirement that the rig need not be craned in and out each day. This research work is ongoing as different concepts are evaluated, and details will be released with the AC75 Class Rule before March 31st, 2018.
The America's Cup is a match race and creating a class that will provide challenging match racing has been the goal from the start. The AC75 will foil-tack and foil-gybe with only small manoeuvring losses, and given the speed and the ease at which the boats can turn the classic pre-starts of the America's Cup are set to make an exciting comeback. Sail handling will also become important, with cross-overs to code zero sails in light wind conditions.
A huge number of ideas have been considered in the quest to define a class that will be extremely exciting to sail and provide great match racing, but the final decision was an easy one: the concept being announced was a clear winner, and both teams are eager to be introducing the AC75 for the 36th America's Cup in 2021.
The AC75 class rule will be published by March 31st 2018.