Radical new foiling America's Cup AC75 class revealed

After four months evaluating a wide range of monohull concepts, Emirates Team New Zealand and Luna Rossa design teams have released a radical new America's Cup Class AC75 foiling monohull capable of extraordinary sailing speeds and on-edge racing.

The design teams’ goals have been to create a new AC class that will be challenging and demanding to sail, rewarding the top level of skill for the crews, while leaving a legacy for future yacht racing and even cruising monohulls beyond the America's Cup.

The result is the AC75, a monohull that 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, which would also useful in rougher sea conditions and thereby provide a wider window for racing (especially in boisterous NZ).

Although racing performance has been the cornerstone of the design, due consideration was given to the more practical aspects of the boat in the shed and at the dock, where both foils are canted under the hull in order to provide natural roll stability and to allow the yacht to fit into a standard marina berth.

Grant Dalton, CEO Emirates Team New Zealand, said he was really proud to present the concept of the fast and futuristic AC75.

"Our analysis of the performance of the foiling monohulls tells us that once the boat is up and foiling, the boat has the potential to be faster than an AC50 both upwind and downwind.

"Auckland is in for a highly competitive summer of racing in 2020 / 2021," said.

LEGACY TECHNOLOGY
The AC design teams say an underlying principle has been to provide affordable and sustainable technology ‘trickle down’ to other sailing classes and yachts.

While 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.

Patrizio Bertelli, Chairman of Luna Rossa Challenge, said the choice of a monohull was a fundamental condition for the team to be involved again in the America’s Cup.

"This is not a return to the past, but rather a step towards the future: the concept of the new AC 75 Class, which Emirates Team New Zealand and Luna Rossa design teams have developed together, will open new horizons for racing yachts, which, in the future, may also extend to cruising.

"It is a modern concept, at the high end of technology and challenging from a sporting point of view, which will deliver competitive and exciting match racing. I would like to thank both design teams for their commitment in achieving, in just four months, the goal which we had established when we challenged."

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 31, 2018.

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, with both teams eager to introduce the AC75 for the 36th America's Cup in 2021.

The AC75 class rule will be published by March 31, 2018.

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