There are just over two months left until the start of the 37th Louis Vuitton America’s Cup and all the teams are working hard in view of the next regattas. The five challengers, Luna Rossa (ITA), Alinghi (SUI), Ineos (GBR), American Magic (USA), Orient Express (FRA), are training with the AC75s in Barcelona to fine-tune the boats and test the field of regatta, while at the end of May the New Zealanders sent the hull with which they will defend the Cup via cargo to the Catalan city and are completing the training sessions with the AC40s in Auckland before moving definitively to Spain. It is difficult to say which will be the fastest boat, so far the crews have not yet compared each other with the new hulls, and for the first judgments we will have to wait for the Preliminary Regatta scheduled in Barcelona from 22 to 25 August.
But at first glance what are the differences between the six AC 75s? We asked Alberto Simeone, a yacht designer who has designed some of the most beautiful boats on the international scene. “It is very difficult to be able to comment on these AC75s without having studied them thoroughly and closely – explained Simeone – from a first examination, Team New Zealand remains the most interesting boat and it is obvious why the Kiwis as holders of the trophy had the advantage of write the Cup regulations. It would seem that the New Zealanders have opted for a more balanced approach in their choices, demonstrating greater maturity in project development. The French team has the same boat as the New Zealanders, having bought the design. Luna Rossa took advantage of the experience accumulated in the previous Cup to create an evolution, while Alinghi, Ineos and American Magic are the teams that have found more innovative solutions for some parts of the hull. What is striking – continues Simeone – is the Americans’ choice to position the “cyclists” (the two members of the crew who use pedals to put pressure on the hydraulic circuit that makes the on-board systems work, ed.) lying down instead of sitting and to more facing aft. Furthermore, while on the other boats the crew is positioned in one row on each side, the Americans have the two helmsmen next to the 2 trimmers (sail regulators ed.). On Alinghi and Luna Rossa the trimmer, protected by a fairing, is the first crew member starting from the bow and is positioned lower than the helmsman to allow the latter a good view, while on board Ineos the trimmer is the last one astern”.
the bow
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“It is interesting – underlines the designer – to note how all the crews worked to try to reduce the risk of “nose diving” (sinking the bow into the water, slowing down and risking getting stuck or capsizing – ed.). In particular, Alinghi has adopted some interesting solutions in the bow area, such as “bumps” (bulges) on the deck near the bow, and a “spray guard” a sort of “skid” similar to that of the hulls of motorboats to concentrate more volume on the bow to increase flotation, perhaps to facilitate a more stern trim and improve the detachment phase of the boat from the water. Everyone has paid great attention to reducing the aerodynamic friction of the hulls, a fundamental aspect for boats of this type type that can exceed 40 knots; for this purpose, the Americans have created a hull with the sides (free edges) apparently lower than their opponents, which would justify the reclining position of the cyclists. Different solutions were also found for the sterns, very flat and squared those of Alinghi and Ineos which could help with aerodynamic support, the stern of New Zealand is narrower and more rounded, while Luna Rossa opted for an intermediate choice. If we compare the side view of all the hulls it is clear that the English chose a completely different path. Their skeg (the central part of the keel), of greater depth, is abruptly interrupted much earlier than that of the others, which instead are tapered up to the stern, furthermore the rudder of the British boat is the only one to be positioned further than the extreme limit of the stern. The reason for this choice? Most likely, with this solution, the vertical forces produced by the rudder foil are greater, and if these are directed downwards, they would increase the stability of the boat with the consequent improvement in the righting of the boat”.
the foils
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The most striking feature of the America’s Cup boats is the foil: “As regards the foils (the submerged ailerons that allow these boats to “fly”, ed.) at the moment it seems that everyone is following the same design concept. Definitely complicated make comparisons on the on-board maneuver regulation systems as they are located below deck, and therefore hidden from external observers, but the solution adopted by New Zealand is interesting which, by providing two independent sheets for the regulation of the two parts that make up the mainsail (the one upwind and downwind), allows for greater versatility in managing lift”.
