When she moved from lecturing at Cambridge to working at MacLaren twenty years ago, Caroline Hargrove was one of the rare women engineers in F1. Simulators were even rarer – no team had one. The simulator Hargrove’s team worked on was limited by the graphics, displays and processing power of the late twentieth century. Adrian Newey dismissed it as useless. The drivers mocked the graphics. Hargrove and her team plowed on. Processor and graphics chips got faster and more powerful. Displays became higher and higher definition. Along the way, F1 limited track time. By the time Newey arrived at Red Bull, he declared that a simulator was one of two key items the team needed. (The other was a gearbox dynamometer.)

Luna Rossa imposed monohulls on Emirates Team New Zealand for the 36^th America’s Cup. Fans of speed and exciting technology groaned. When the protocol was presented in late September, ETNZ promised an exciting new boat. Many, including your scribe, doubted. Like Euripedes, searching for a dramatic, surprise ending to one of his plays, Dan Bernasconi and the ETNZ design team turned to their “machina” – the simulator, to conceive the AC75 and stun the sailing world. In the weeks since they released their concept video, intriguing details are starting to emerge.

Having “sailed” the AC75 extensively in their simulator, ETNZ tell us that it should foil in nine knots of breeze. Rather than raking the foils to control angle of attack, like the AC72 and AC50, the AC75 foil wings will have flaps to vary the lift. In “normal” mode the leeward foil wing provides lift and is the fulcrum. Righting moment comes from one to one-and-a-half tonnes of ballast in the windward foil wing, and also from the entire weight of the hull, rig and crew. The single rudder will probably have rake control and may have elevators on its horizontal stabiliser, to provide pitch control.

In “stable mode” with both boards in the water, ETNZ predict that the AC75 can stay up on the foils through pre-start circling – two foils can provide double the lift with only a slight drag penalty from the additional wetted surface. After the start, a team might sail with both foils down in rough conditions or in windspeeds in the displacement-to-foiling crossover range. The rule will prohibit teams from using downforce from the windward foil to provide righting moment. In the upper wind range this would put high loads on the rig and the hull. The hope is to keep the total righting moment fairly constant over the wind range. In a recent interview, Bernasconi said he hoped to get the upper wind limit close to 25 knots.

Rig concepts were still under discussion in early December. A completely rigid wingsail has been ruled out in favor of “something hoistable.” Possible solutions include a wing mast with a soft sail, possibly inflatable or with two layers forward. The main might have a reef, but a smaller sail with the same hoist and a smaller chord is the more likely solution for muscular conditions.

The crew, likely to be twelve, will have plenty to do. The crew weight limit will be higher per man, signaling the return of big grinders. Grant Dalton has said there will be no cyclors and that “we will never introduce a combustion engine.” There will, however, be battery power to drive the hydraulics needed to lift a tonne or more at the end of a five meter long foil arm. The crew will need to trim and tack the jib – the self-tacking jibs from the AC72 and AC50 are gone. In light wind the Code 0 will need to be hoisted and dropped. During gybes the grinders will provide power to furl and unfurl it. Of course, we may not see much of the Code 0 in the high-speed, narrow angle, apparent wind sailing that the AC75 promises.

Safety requirements may include requiring crew to be tethered when working on the foredeck. The scythe-like foil wings remind some pundits of the chariot race in Ben Hur. Bernasconi points out that the windward hull of a foiling AC50 was pretty ominous, too. He describes an ellipse- or diamond-shaped virtual exclusion zone around the boats, visible on displays for the crew, the umpires and the audience.

Some components will be one design. The power source, hydraulics and bearings for canting the foils are likely to be supplied equipment. The foil arms might be one design. Foil wing design and flap controls will probably be designed by each team. We can imagine a variety of streamlined shapes installed around the ballast in the foil wings. The number of foil cards allowed by the rule has yet to be determined. The mast is another potential candidate for being one design. Hull design will be up to each team. The speed advantage of foiling over floating will drive the CFD specialists to focus on minimising liftoff speed. The boats will probably fly less than a metre off the water, so touch-and-go-friendly hull shape will be a design goal.

Teams can splash their first AC75 at the end of March 2019 – one year after the promised release of the AC75 rule. But there are a few devils in the protocol’s details. Presumably the venue will be Auckland, but RNZYS has until 30 August 2018 to confirm. That means potentially up to five months of uncertainty over racing conditions. The protocol also gives the defender and CoR ninety days to make changes to the class rule after it is released, for any reason. ETNZ promised a “fair and transparent event,” so any changes to the rule will probably be to correct minor errors.

The AC75 will test the designers, boat builders and sailors to the limit. Not to mention the simulator builders. It will be interesting to see who can build the best machina from which to extract a god capable of lifting the Cup in 2021.