The AC40 is a one design (so they're all exactly the same) foiling monohull that has been designed, built and manufactured by Emirates Team New Zealand. It will be used by all the competing teams in the first two preliminary regattas of the 37th America’s Cup. It’s a smaller, 40 foot version of the AC75 yacht – the bigger sister will be used in the final preliminary regatta, the Challenger Series and the America’s Cup. Meanwhile, the AC40 will go on to be used in the Youth and Women's America's Cups, also contested in the autumn of 2024.
There’s no one generating power on the boat, no grinders or cyclors, it's all powered by batteries. So down below are three batteries to power the big hydraulic rams controlling the foil arms, the flaps on the wings, and the sail controls. There’s also all the electronics controlling the autopilot and the control functions used by the sailors on deck. Leigh McMillan is going to guide us through the experience of sailing the boat.
“The helm is in pole position right at the front, with the best view of the racetrack to make all the best possible decisions. On this boat, you've got the crew split side to side. There's no swapping when you're tacking and gybing. So when you're to windward you're helming and making the boat go fast, and when you're to leeward you're heads out of the boat and looking for those key decision points.”
The biggest difference between the AC40 and the AC75 is that the former has an autopilot to keep the boat flying at a consistent height above the water, and with a steady angle of trim relative to it. On the AC75 the job has to be done manually, with strict regulations to control the inputs from the onboard computers. “Ultimately the aim of the game here in the AC40 is to have the best possible racing. So it's just simple controls in the autopilot, so you can be heads out of the boat as much as possible to make the best possible decisions,” said Leigh.
“But you do have to input how you want the autopilot to control the boat,” he explained. “So how high and what the trim of the boat is actually going to be. So you'll be making those adjustments depending on the conditions… making adjustments into manoeuvres so that the boat is performing optimally.
“The primary buttons when we're in race mode are either side of the steering wheel. We've got a board up and board down button for in and out of manoeuvres. We've got a height button which is controlling the immersion of the foil when flying along. We've got a cant position which moves the [foi] arm in and out, to set up the optimal cant and heel of the boat.
© Alex Carabi / America's Cup
Alex Carabi / America's Cup
“We've also got a port / starboard mode controller which swaps the side of the boat that you're controlling. So you can pretend that you're on the other side of the boat, to control the functions for the other helmsman, plus there are also trim buttons which control the pitch of the boat.
The boat uses two displays for the helmsmen – both are based on a smartphone. “One of them will have mostly the tactical app information, and the other gives you some of the key data for all of the functions you're adjusting,” explained Leigh.
The second position on the boat is for the two trimmers, also one on each side. “They are controlling all of the sail functions [with a] control unit underneath the deck... When you're to windward you're primarily in control of the mainsail functions… to leeward you're mainly in control of the jib functions.
“There's a critical moment in the tacks and gybes when you're setting up the sail, but also transferring that role to the other crew, swapping functions and making sure that at the exit of the manoeuvres and the entry of manoeuvres you've got everything set up correctly on your side. You're also communicating to the helms, the targets and the boat speed, and where the boat might be in terms of performance at any given time.
“It's a very dynamic position in terms of having to move the traveller a lot to keep the heel of the boat as accurate as possible. You're trying to keep the heel at the optimum without getting those touchdowns, getting the bustle of the hull hitting a wave, which has quite a big slow down effect on the boat.
There are control buttons for mainsail or jib mode, the sheets of both sails and the traveller for each sail. There’s also a control for the mast rotation, and a button that automatically inverts the rig to the same position on the opposite tack. There’s an outhaul, or clew position controller, and a Cunningham controller, together they allow the sails to be set up for the conditions; deep and powerful to accelerate, or flatter when the boat is moving fast.
“The most active control as a trimmer is the mainsail traveller at the back of the boat. And you'll be controlling that all the time to try and keep the heel of the boat as accurate as possible and not touching those waves.” This is the job of the windward trimmer. “And you'll also be communicating to the helmsman on the moding of the boat; whether you want to push for a bit more speed or climb for a bit more height. And just generally looking for those pressure differences [in the wind] and those pressure calls to make sure the boat is anticipating the changes of mode required.
“One of the key aspects for the helmsman is going to be communication, knowing where all of the competitors are and determining what the tactical decisions are… and communicating the next move all whilst going at maximum speeds of over 45 knots with the wind blowing through your ears. That communication is going to be absolutely critical to the results… between Ben and Giles communicating where all the other boats are.”
Most of the racing in the preliminary regatta is fleet racing, so there are a lot more than the two boats that will eventually face each other for the America’s Cup. “From one side or the other of the sails you have very limited visibility. So painting the picture from around the [race] course for what the next strategic decision is likely to be is going to be absolutely critical to the success of this team,” concluded Leigh.
Racing in Vilanova takes place from 14:30- 16:30 BST and is available free-to-view via the official America’s Cup website, AmericasCup.com, so there’s no need to miss out. It’s definitely back, the 37th America’s Cup is finally on.