The majesty of the J Class (above) with the performance of the AC50s… that in a nutshell was the brief to the Team New Zealand designers. No one imagined a new Cup class on the scale of the outrageously indulgent J boats but from the Italian Challenger of Record the message was clear: ‘The 36th America’s Cup Match will be raced in monohulls.’ To be fair to Team NZ they delivered a monohull (right) and on paper it promises electrifying AC50-type performance. Majesty… that always was a matter of interpretation


untried concept has been proposed. This is the biggest uncertainty on the path to the next Cup. Here again Luna Rossa have made their presence felt. They withdrew from the last Cup because the foiling catamarans plus the short inshore races didn’t feel like a ‘proper America’s Cup’; they made no secret of their desire to see the Cup back in large monohulls with soft sails and a more ‘majestic’ look and feel. On the other hand, the Kiwis had just won in a complex foiling machine that had excited the viewers. It was obviously in their interests to keep the Cup in the vanguard of racing yacht development. After a great deal of wrangling they have


come up with a compromise solution. Make no mistake, it is a compromise. The design- ers have done enough homework to persuade themselves it can be done, but it’s difficult to say if the introductory AC75 video is a bona fide simulation or merely CGI à la Game of Thrones. Whatever the answer no boat like this has been raced any- where, ever. This a first in America’s Cup history – even the AC50 was a progression over three America’s Cups. If the boats don’t work on the racecourse then it’s a problem. The concept is a hybrid of an Inter -


national Moth and the latest big foiling trimarans. The foil in the leeward hull does the job of the centreboard, stopping the boat sliding to leeward, and also produces a vertical force that lifts the boat out of the water and produces the lion’s share of the righting moment. At sailing speeds of 30kt+ the righting moment will be three or four times more than on the AC50. Be assured, these boats are super-powerful. There are two obvious unknowns. Can


you easily maintain steady flight? How easy will it be to get onto the foils? In the last Cup we were used to seeing


races being won or lost when one boat lost a big distance by falling off the foils. On the new offshore hydrofoiling trimarans the hull and outriggers are buoyant so if ride height control is not perfect and you come off the foils good old Archimedes will look after things. On the new AC75 there is no such


buoyancy safety net so the penalty for a crash will be great. The International Moth works so beauti-


fully because it has a simple automatic ride height control using a surface-sensing wand linked to a flap on the main hydrofoil. Because this system needs no external power supply it complies with the Racing Rules of Sailing. On the AC50 a modicum of stored power was permitted, but no ride height sensing was allowed. This left the boats much harder to control than the little Moth. On five of the six Cup boats the helmsman was continually making foil adjustments to stay flying which massively distracted him from his core task of racing his opponent. It is clear to me that to achieve the highest


performance some form of autopilot and low energy consumption foil system will be needed. This will be an interesting tussle between the forces of conservatism and pro- gression. I feel the AC50s were hampered by a class rule that left the boats starved of power and lacking state-of-the-art control mechanisms. To get the best out of the new boats these issues need to be addressed; we need boats that are great to sail and watch without them becoming completely auto - nomous. Get this right and it will be a step forward for the whole sport. Additionally, the reliance on hydro -


dynamically generated righting moment will make the acceleration phase from a pre-start dial-up quite taxing. On the Moth and the AC50 the righting moment comes from the weight of the crew on the windward side of the boat. This means that whatever its speed the boat has the same righting moment and therefore the same power available to accel- erate. On the AC75 the righting moment comes from the lift off the leeward foil, and at 30kt it will have four times as much oomph as the AC50. But at slow speed the foil lift is very low. The crew weight and ballasted windward


foil are only 10-15 per cent of the righting moment when the boat is going 30kt. So while in steady flight the boat is super- powerful and fast, at low speed it has less


righting moment than the AC50. Getting across this valley of death from 5kt to 20kt will need some fancy footwork. So even more reason to avoid a crash, even more reason to make sure your power supply and control systems are top class. Finally, the timescale mooted in the


Protocol is challenging. The 36th America’s Cup is scheduled for the early months of 2021, or mid-year 2021 if it’s in Sicily. The ‘World Series’ races may start as early as the second half of 2019. You are allowed to launch the first boat after 1 March 2019, and the second after 1 February 2020. The class rule won’t be workable to the


extent that detailed design work can be done until the middle of this year. If it takes nine months to build a boat, which it does, some- thing has to give. Most likely it will be the World Series events, and this is presaged by Article 8 of the Protocol which permits alter- native boats to be used at the discretion of, you guessed it, the Defender and CoR. This is a potential problem because the


World Series events are a huge part of the Partner fulfilment programme for the com- mercial teams. They offer engagement over the months and years before the Cup to grow interest and justify a meaningful finan- cial input. It’s not a problem for Luna Rossa, they have private funds. It’s not a problem for the Defender, they always make it. But it is a problem for commercial teams who will be burning through £15-20million a year. It’s going to be hard to excite interest and


draw in funds if the first few World Series events don’t have the full razzmatazz of America’s Cup racing. (Racing the World Series in non-Cup boats was unsatisfactory, and one of the key planks of the Framework Agreement was to race the World Series events in the AC50.) None of this is to suggest that the next


America’s Cup won’t be a great success – they usually are. But at this stage the unholy alliance between Defender and CoR, the untried nature of the boat and the challeng- ing and uncertain timescale would keep me awake at night.


q SEAHORSE 51


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