AC40: the America’s Cup class’ younger sister

Yachting World

All about the AC40, which will be used for the Youth and Women’s America’s Cups and the America’s Cup preliminary series

The 37th America’s Cup may be retaining the AC75 – albeit with a tweaked rule set – for actual Cup racing, but there will also be a new kid on the block in the form of the AC40. This one-design foiling monohull will be used by teams for training, development and America’s Cup preliminary regattas.

The purchase of one AC40 will be a prerequisite to entry into the 37th America’s Cup with the boats being used for an America’s Cup preliminary series (consisting of two events in the run up to the Cup itself), and also the reintroduced Youth America’s Cup.

Both the Youth AC and Preliminary Events (previously called the America’s Cup World Series) concept have been a feature of past America’s Cups, but both were dropped in the run-up to the 36th America’s Cup in Auckland.

The 37th AC will also introduce a new concept in the Women’s America’s Cup, which will also (controversially for many) take place in the smaller AC40 class that the youths will use.

The first AC40 is now in production by builders McConaghy Boats and is promised for delivery in July 2022 with production slated to be one new boat every five weeks thereafter.

Teams entering the America’s Cup and so purchasing an AC40 will also be given access to a simulator developed by Emirates Team New Zealand for pre-delivery training.

Emirates Team New Zealand’s training boat, Te Kahu. Photo: James Sommerset / Emirates Team New Zealand

The birth of the AC40

In the run up to the 2021 America’s Cup all teams tried out various test boat platforms – often modified 30-40ft racing yachts – in order to get to grips with the previously untried new concept of keel-less large foiling monohulls that had been introduced for the AC75.

These test boat platforms were used by the teams to test foil shapes. For some, it was also a first opportunity to start getting to grips with the complex soft wingsails that had been newly introduced to the America’s Cup world with the AC75 rule.

The last team to launch a test platform was the (successful) Defender of the Cup, Emirates Team New Zealand.

The Kiwis were last onto the water with their test boat (they launched Te Kahu, the test boat, after their first AC75 hit the water but before their second race boat AC75, Te Rehutai), and also had the advantage of the team’s highly advanced simulator and computing platform. So it’s unsurprising that the New Zealand team’s test boat looked easily the most polished and closest to the AC75s in almost every way.

It is also hardly surprising that, as Defender and co-writer of the 37th America’s Cup rules, the new one-design AC40 class looks very similar indeed to both Te Rehutai (from which the hull shape is taken) and Te Kahu.

AC40 control details

How does the AC40 work?

The AC40 is designed to behave in a similar way to the AC75. They have two large, weighted foils on either side of the boat but no traditional keel.

The boats are designed to foil on one foil only with the windward foil raised out of the water to reduce drag and provide increased righting moment.

With only four crew members onboard the AC40 there will be a reliance on a variety of automated systems, including a battery powered system replacing the need for grinders, and automated controls to adjust foiling height and self-tacking headsails.

In terms of the rig, the AC40 will mimic the AC75s and will feature the same D-shaped mast on which two sail skins will be hoisted to create a soft wingsail, offering plenty of control but a sail plan that can be easily raised and lowered from onboard.

As with both the finalists in the 36th America’s Cup there will not be a boom, with a variety of hydraulics used to shape the sail from foot to head.

Southern Spars will supply the mast spar, while North Sails will be the supplier for the sails.

Is the AC40 a one design?

The AC40 concept is designed to meet a variety of criteria, providing one-design racing in the run-up to the America’s Cup itself (and for the Youth and Women’s AC) but also to function as a test platform for the teams to develop and trial concepts ahead of building their AC75s for the America’s Cup proper.

This second function is vital to control costs – it is much cheaper to develop concepts on a smaller class than it is on the larger AC75.

But when it comes to the two preliminary events ahead of the AC (a third preliminary event will be sailed in AC75s), the Youth America’s Cup, and the Women’s America’s Cup, all boats will need to be stripped back to conform to the one-design AC40 rule.

AC40 perfromance polars

AC40 Performance

In their modelling so far, Emirates Team New Zealand report that in light winds the AC40 is expected to be able to sail at up to 26 knots at 46º upwind and 30 knots boat speed at 138º downwind.

At the upper limits of 20 knots TWS, the boat speeds are expected to escalate to 39 knots upwind at 41º and 44 knots at an angle of 155º downwind.

Can I buy an AC40?

In theory, an AC40 can be bought by anyone, allowing for the possibility of private ownership. As a further step on from this, Emirates Team New Zealand say the simulator will be available to private owners, should anyone be looking to purchase one of the scaled down AC class.

Whether or not any private owners would be tempted by this remains to be seen. It would certainly be a thrilling boat to own, though running costs and complexity could also be incredibly high.


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