Guide to the new America’s Cup AC75s: compared for the first time

The New AC75s, protagonists of the upcoming America’s Cup, compared for the first time

The 37th America’s Cup is approaching, and excitement is rising not only among the race challengers but also among the numerous passionate spectators who will follow the world’s most captivating nautical competition, scheduled to start from August 22nd in the waters of Barcelona. In recent days, the four teams in competition have carried our the first tests of their AC75s, which incorporate various naval engineering solutions aimed at competing for the coveted title. Let’s take a look at what it’s all about.

Emirates Team New Zealand and Luna Rossa Prada Pirelli have so far only shown a fraction of their potential, as both AC75s have been tested with legacy foils and foil arms. Alinghi Red Bull Racing, on the other hand, has already started using the new running full-span bespoke foils which clearly have had an enormous effect on performance. But as mentioned above, these are only temporary differences.

Regarding the hulls, all the teams have gone for T-section shapes at the stern run-off but only Alinghi Red Bull Racing has opted for its particular bow profile that extends full length to the stern. However, it’s in the bow area where the differences are most marked. INEOS Britannia have real volume in their in-built immediately voluminous bustle, whereas Emirates Team New Zealand and Luna Rossa Prada Pirelli have aggressively flared bow profiles back to the foil arm boxes.

The deck area is key. For anyone that has seen an overlaid flow diagram of an AC75, the biggest disturbance air passing over the yacht is at deck level and it’s here where designers and technicians have worked the hardest. The Italians of Luna Rossa Prada Pirelli have opted for a beautifully contoured naked carbon approach, moulding the side pods evenly into the deck and aft off the transom. Emirates Team New Zealand does the same with a raised ellipse stern that screams aero.

On the other hand, Alinghi Red Bull Racing has special protrusions at the bow, designed to promote airflow to the jib, along with an incredibly open cockpit that creates a kind of tunnel with raised pods. INEOS Britannia, instead, appears to be somewhere in the middle of the Italians and Swiss with blended side pods streaming aft – we will know more when they officially launch in the coming days.

The biggest differences between the four yachts lie in the treatment of the bustles and skegs that run down the middle of the boat. What we see on the Swiss AC75 is almost an International Moth style of skeg whilst for the Kiwis and Italians they have a more blended, considerate approach. Specificallu, Emirates Team New Zealand’s bustle runs full length, kicking up in the final third to the transom allowing for the rudder to be hung beneath the bustle. Its angularity is marked, similar in fact to the sharpness of INEOS Britannia’s treatment although their bustle stops a few feet from the transom tip, meaning the rudder mechanics are mainly all above deck.

Lastly, the Swiss have considerable volume at the stern in their bustle with the added benefit of getting those rudder controls low and hidden. Same too for Luna Rossa Prada Pirelli whose refined bustle goes full length and again has the rudder slung off the underbelly. All the boats so far have a keel chine running off the bow with varying degrees of depth.

Another similarity between the four yachts appears to be in crew configuration with everyone so far going for the trimmer in the forward pod, followed by the helmsman and then the two cyclors in the aft. A screen on the forward pod of Alinghi Red Bull Racing confirms their aero intention whereas for the other trimmers, it’s just a very low position out of the wind that they maintain.

Same too for the cyclors of the AC75s competing in the 37^th America’s Cup. They are arched into an almost time-trial position with their heads down in the ‘pain-locker’ pedalling for all they are worth – rarely do you see a cyclor look up when the boats are in motion.

In terms of sail control, we can see that all the teams have opted for trench configurations on both their jib track and mainsheet track but there’s a world of difference and new thinking going on here. Emirates Team New Zealand have innovated once again and removed all of their control componentry below the aft deck to produce a very neat dual control system that auto-varies side to side and gives them ultimate control over both skins of the mainsail. Jib systems all look to be sunken 3D controls mounted on self-tacking tracks and all the teams have been seen linking up mast rotation to the mainsheet system. Pre-sets will become defined as the teams ramp up their time on the water, making these AC75s some of the most refined and setting-repeatable boats in the world.

One of the closely guarded areas of development is the foil design. Emirates Team New Zealand and Luna Rossa Prada Pirelli have both opted at launch to keep their designs secret and complete the commissioning of their boats on legacy foils. Alinghi Red Bull Racing, however, did not have this option and what we saw at their launch was a first iteration of the long-span, low volume foils that are beautifully sculpted with almost invisible dual flaps and upturned wing tips. Designed for super-fast flight and early foiling, we’ve already seen the Swiss get airborne in just 6.5 – 7.5 knots of breeze which is an impressive performance upgrade on the first-generation boats.

INEOS Britannia revealed their boat but kept their new foils shrouded until launch. What we can certainly see is the trend for back slung foils off a slender bulb – expect this to be the norm. Now we just have to wait for the continuation of sea trials and then, finally, the much-awaited competition that will last until October.