The three challengers will start their assault on the America’s Cup this week as the Prada Cup gets underway. Matt Sheahan assesses each of the teamsA spectacular skyward launch for American Magic\u2019s Patriot during early trials. The focus of these latest Cup boat designs is as much on aerodynamics
\nas hydrodynamics. Photo: Will Ricketson\/American MagicAs each of the new AC75s were wheeled out into the open for the first time, amid the celebration and champagne spraying, each team will have been keenly aware that this was it.
\nBarring disasters, these were the boats that would face each other on the start line. After more than two years of planning, scheming, data-crunching, building, testing and training, this was their shot at the America\u2019s Cup.
\nThe pressure has been made even greater by a distinct lack of any opportunity to compare themselves against the other teams, after the two 2020 America\u2019s Cup World Series events in Sardinia and Portsmouth fell victim to the pandemic.
\nArticle continues below\u2026<\/p>\n
\t\t\t\t\t\tINEOS Team UK grinder David Carr explains what it\u2019s really like to sail an AC75<\/p>\n
\t\t\t\t\t\t\t\u201cWhen you push off the dock, your life is in the hands of computers \u2013 and the guy piloting the\u2026<\/p>\n
\t\t\t\t\t\tRoad to the America\u2019s Cup podcast: What can sailing simulators teach us?<\/p>\n
\t\t\t\t\t\t\tThe reason is simple: every other means of performance evaluation has been neutered \u2013 or, at the very least, significantly\u2026<\/p>\n
Had they gone ahead, these regattas would have provided valuable intelligence about the relative performance differences across the fleet, and some clues about which design approach was pursuing the right path. Much of that knowledge would have been gained while there was still time to do something about it. Now there is none.
\nThe result is that, despite all the \u2018competitive reconnaissance\u2019 \u2013 or what you and I would call spying \u2013 that every team has been engaged in since the 36th America\u2019s Cup cycle started, rarely has so little been known by the competitors about their opponents.
\nTrue there has been opportunity for the four teams to pit themselves against one another in the America\u2019s Cup World Series and Prada Christmas Cup \u2013 the latter ultimately cut short due to a lack of wind \u2013 but this represented very little competitive sailing for all teams.
\nNot that the lack of racing has stopped others from speculating on the relative speeds of each team. Before the launches, there was a school of thought that, despite some wildly different design approaches for the first boats, the second AC75s might show the four designers\u2019 thinking had shifted towards a similar corner of the rule. But when the new boats were unveiled it was clear that such a consensus did not exist.
\nBritannia II takes flight in Auckland\u2019s Hauraki Gulf. Photo: C Gregory \/ INEOS Team UK
\nIneos Team UK
\nThe boat \u2013 Britannia II
\nThere\u2019s no disputing the British boat is the most extreme of the challengers. The most noticeable feature is her chunky, aggressive skeg that starts like a battering ram at the plumb bow and runs down the centreline, stopping just in front of the rudder.
\nThe broad purpose of a long skeg, to maintain an aerodynamic seal between the hull and the water\u2019s surface as the boat begins to fly, is becoming increasingly clear, but little is yet known about why chief designer Nick Holroyd and the British team have gone for such a chunky configuration.
\n\u201cIt has benefits through the take off and aerodynamically when the boat\u2019s flying as well,\u201d Holroyd said of the \u2018bustle\u2019, as he referred to it.
\nBritannia II\u2019s skeg \u2018bustle\u2019 is obvious from this angle. Photo: C Gregory
\nInterestingly this deep, box section affair doesn\u2019t appear to be aero- or hydro-dynamically sympathetic until you look from under the boat. From this angle the bulge in the box section as it travels aft suggests that the skeg is generating hydrodynamic lift somewhere around midway down its length.
\nThis would imply that the longitudinal position of maximum lift would be somewhere near the foils. Perhaps, when the boat is heeled to weather and getting ready to take off, the water flow on the windward side reduces leeway by sucking the boat up to windward which helps to get the leeward foil working?
\nThere\u2019s also a question whether the box type section of the skeg provides a lighter structural beam to make the hull stiffer fore and aft. If this is the case it could be that space has been freed up inside for systems and\/or that it means the weight budget for structure can be used in other areas.
\nAnother interesting feature is the distortion in the hull shape aft which appears to be a way of reducing the waterline beam and therefore wetted surface area quickly as the boat lifts, which in turn will provide a step change in acceleration \u2013 a performance aspect that will doubtless prove critical on a race course that has plenty of corners and boundaries to accelerate away from.
\n\u201cSlow speed manoeuvring is quite difficult and the initial stage of acceleration is tricky,\u201d said team pilot Leigh McMillan, the crew member responsible for flight. \u201c[But] the acceleration through the mid-range is going to be a huge step forward.\u201d
\nThe British High Commissioner for New Zealand, Laura Clarke, helped Sir Ben Ainslie christen the boat in Auckland. Photo: Harry KH
\nHow are they faring so far?
\nWhichever way you look at it, Britannia II is a radical shape but so far the team will be disappointed with their showing on the America\u2019s Cup World Series, where they were clearly the slowest team by a distance.
\nThe British boat does not seem to be particularly sluggish in a straight line so far as can be said based on what little was seen in the ACWS, but they do appear to struggle to get up on their foils as quickly as the other boats and seem to drop off them a little earlier.
\nAny number of factors could well be contributing to this from the \u2018soft wingsail\u2019 not providing sufficient camber and so power at the bottom of the wind range, or the foils not being quite as optimised or any number of other factors.
\nAinslie was relatively forthright about the work they had ahead at the end of the event stating that: \u201cWe\u2019ve got the spend the next two or three weeks making some big changes to the set up.
\n\u201cClearly, as we keep saying, there are issues with our performance in the down-speed sections and we\u2019re obviously trying to evaluate that, work out what\u2019s causing that, and rectify it.\u201d We\u2019ll soon see if they have managed to fix their issues but it was far from a dream start to competitive proceedings for the Brits.
\nThe crew
\nOver 170 years of America\u2019s Cup racing, Britain has what can only be described as the longest losing streak in history. The Brits were left bruised after defeat in Bermuda, and there have been a few changes since then.
\nOn the AC75 Giles Scott is calling tactics for skipper Ben Ainslie, with Leigh MacMillan as flight controller. Add in Cup veterans David Carr and Nick Hutton, and some additional muscle from the likes of Olympic rower Matt Gotrel, and the team seems settled and tight-knit.
\nLuna Rossa has arguably the sleekest hull of the four challengers
\nLuna Rossa Prada Pirelli
\nThe boat \u2013 Luna Rossa
\nThe Italians\u2019 Luna Rossa looks the sleekest of them all. With smooth elegant lines and a complete absence of hard edges or distortions, this is a boat designed to fly rather than float.
\nWhen viewed in elevation, the hump in the sheerline from midships aft seems to highlight just how important aerodynamic lift is and how the deck can now be used to contribute to lifting the 7-tonne beast out of the water.
\nSimilar to Patriot, Luna Rossa has a skeg that blends its way out of a bow (that in profile looks like it came from their 2002 IACC boat), before running down the centreline to stop in front of the rudder. Even so, this is the most modest of all the skegs.
\nPhoto: Giulia Caponnetto
\n\u201cWe\u2019re pretty happy with what we have done and the evolution of our boat,\u201d said chief designer Horacio Carabelli. \u201cI think we have stepped up pretty well. It\u2019s just small details that we really improved from our first generation boat.\u201d
\nAlthough Carabelli and the team were keen to play down any developments that may have taken place between boat one and boat two, the 2020 chatter was about how sophisticated their first boat looked.
\nPerhaps the reality is that Luna Rossa was a lot further down the hull development line than the other two challengers for their first boat and have since been able to concentrate on other details that are less obvious. They were the only team to mask out shots of the twin cockpits.
\nWithin those twin cockpits lurks a unique feature of the Luna Rossa boat with the Italian team electing to go for a twin or split helmsman option. Jimmy Spithill will steer the boat on starboard tack while Francesco Bruni steers the boat on port, with neither helmsman crossing the boat at any point during racing.
\nWith all other boats we see helmsman running across the boat after manoeuvres while another member of the afterguard temporarily holds the wheel.\u00a0 It seems the \u2018spare\u2019 helmsman can then offer tactical input from the leeward side and possibly takes on foil control or mainsail traveller control.
\nHow are they faring so far?
\nWhat it does mean, and this could clearly be seen in the America\u2019s Cup World series, is that Luna Rossa is extremely manoeuvrable and they were the only team to look unharried by multiple manoeuvres, such as mark roundings immediately followed by a tack, or quick tacks in succession. It hardly need be spelled out what a boon this could be in a tight match racing situation.
\nPhoto: Luna Rossa Prada Pirelli
\nThe crew
\nThe Luna Rossa Prada Pirelli team hasn\u2019t been afraid of ruffling a few feathers in the run-up to this Cup, but helmsman Jimmy Spithill isn\u2019t the type to be bothered by a bit of conflict.
\nWith a Cup record equalled only by Russell Coutts, Spithill is a very hard man to bet against. Team skipper Max Sirena has also been on the winning side both alongside and against Spithill, with USA 17 in 2010 and ETNZ\u2019s winning crew last time.
\nPhoto: Sebastian Slayter\/American Magic
\nAmerican Magic
\nThe boat \u2013 Patriot
\nThe American team were first to launch both iterations of the AC75. On the face of it, Patriot looks much like her sistership Defiant, but the differences start to become clear when you look at her bow.
\nGone is the scow shape with its overblown Topper dinghy-style deck and flat bow sections and in comes more of a V-type bow, albeit still under a beamy foredeck.
\nHere, the flared forward sections create the start of the centreline skeg that runs aft for around 75% of her length. Skegs have become a feature of all four new boats as designers attempt to maintain the seal between the hull and the water\u2019s surface for as long as possible in order to maintain aerodynamic efficiency.
\nAmerican Magic\u2019s slender hull and curved deck is influenced by the smooth aerofoil shape of an aircraft\u2019s wing. Photo: Will Ricketson
\n\u201cThe flare in the bow is just maximising the driving force and minimising the heeling moments that you\u2019re producing,\u201d explained designer Marcelino Botin. \u201cThe bow shape and the whole boat is guided towards that objective.\u201d
\nApart from a high gloss finish that is very effective at concealing what she really looks like, Patriot is notable for her smooth, undistorted shape below the waterline and her aerodynamic shape above.
\n\u201cYou should look at the hull shapes as a continuation of the rig and the sail plan,\u201d continued Botin. \u201cWhat you\u2019re trying to achieve with the hull is to maximise the driving force of the rig and the sails and minimise the heeling moment, it\u2019s as simple as that.\u201d
\nIf you look at all of the designs with this in mind you can see areas where this is the case: one example is the wide flat central section of the deck between the crew (who are lined fore and aft up along each gunwale), which dips gently towards the cockpit sole as it sweeps aft keeping the airflow over the deck and around the bottom of the mainsail clean.
\nWith apparent wind speeds that are regularly in the 40-60 knots range it\u2019s not difficult to see how a curved deck like this can act as a lifting device; there are plenty of aircraft that fly at these speeds and less.
\nPhoto: Will Ricketson\/American Magic
\nAnother notable point is the depth of the rudder. The top of the blade has a long chord to provide control at slow sub foiling speeds while the lower tip of the blade is a painfully skinny affair to reduce drag and avoid cavitation.
\nHow are they faring so far?
\nPatriot was the stand-out performer of the challengers in the America\u2019s Cup World Series and were the only team to beat the America\u2019s Cup Defender, Emirates Team New Zealand in a race.
\nThe American team\u2019s tactic of launching each iteration of AC75 first and getting as much time on the water in them as possible seems to have paid off, at least initially, whether the other two challengers are able to bridge that gap and whether others have a package that is ultimately quicker with more time to set up remains to be seen, but it would certainly not be a surprise should Patriot line up against the Kiwis come the America\u2019s Cup final based on their ACWS pace.
\nThe crew
\nIt will have been a strange homecoming for Dean Barker when he arrived back in New Zealand to take the wheel of Patriot. Barker was the country\u2019s hero when he won the Auld Mug for the black boat in 2000, but after losing twice to Alinghi and then to BMW Oracle in 2013 he was removed from the skipper position and has been helming for other nations since.
\nAs well as skipper Terry Hutchinson, much of the team\u2019s DNA comes from backers \u2018Hap\u2019 Fauth and Doug DeVos\u2019s successful Bella Mente and Quantum Racing programmes.
\nThe Defender
\nPhoto: Gilles Martin-Raget
\nEmirates Team New Zealand
\nThe boat \u2013 Te Rehutai
\nEmirates Team New Zealand, as holder and Defender of the America\u2019s Cup will not compete in the Prada Cup, that competition is merely to decide who gets the right to sail against the Kiwis in the America\u2019s Cup match itself. However, all the signs point to the New Zealanders being a more than worthy opponent for whoever comes out as the top challenger.
\nIt\u2019s difficult to overstate how eagerly anticipated the launch of the Kiwi\u2019s second boat was. Besides being the current America\u2019s Cup holder, Emirates Team New Zealand has set the foiling agenda since 2012.
\nBeing the architects of the new rule delivered another opportunity to stretch further ahead. This is how the Cup works: win it and you get to make the rules. This is a design team that has been ahead of the curve for two consecutive Cup cycles already.
\nThe most striking aspect of the new boat is how similar in concept it looks to that of INEOS Team UK. Despite their different starting points, the two teams appear to have arrived at a similar design place.
\nThe aggressive, muscular approach is first evident with a long, deep and chunky skeg that runs the full length of the boat. Like on the other AC75s, this feature provides an aerodynamic seal up until the point at which the boat starts to take flight, plus it may also contribute to the hydrodynamic side force at displacement speeds.
\nTe Rehutai features a prominent skeg and flared hull. Photo: Gilles Martin-Raget
\nWhen viewed from underneath it appears to be a more parallel sided section than that on the British boat. It is also possible that this chunky skeg provides an efficient, beefy structural spar for longitudinal stiffness.
\nThen there is the heavy flare in the forward sections of the hull, which roll out into flat, horizontal sections aft.
\nSuch clean flat areas pushed out to maximum beam result in vertical topsides, suggesting the Kiwis believe there is a well defined step between displacement sailing (where maximum form stability will be required), and flight. The complex underwater shapes of the British approach suggest that there are more stages to this transition.
\nIt is this transition, and how it impacts on the ability to accelerate quickly, that is one of the key cornerstones of performance, as confirmed by ETNZ\u2019s head of design Dan Bernasconi.
\n\u201cWe\u2019ve been searching for the perfect balance between hydrodynamic and aerodynamic performance,\u201d he said. \u201cAn AC75 that was optimised purely to accelerate and take-off would look very different to one which was optimised for steady flight, and that\u2019s reflected in the huge variation we see between our competitors\u2019 yachts in the fleet.
\n\u201cTe Rehutai is designed to excel in both domains \u2013 the water and the air \u2013 and we\u2019re confident she\u2019ll be competitive across the range of wind-speeds we may see in the America\u2019s Cup.\u201d
\nHow are they faring so far?
\nIt\u2019s hard to see the Kiwis\u2019 performance in the America\u2019s Cup World Series as anything other than ominous \u2013 unless you happen to be one of the many die-hard New Zealand supporters who will, no doubt, be delighted.
\nThe Cup holders did look beatable on the water, losing a race to Patriot, but even during that tight battle they looked to have a click more boatspeed at certain times with tactical or crew work errors the key factor in any less-than-stellar performances.
\nYou would typically pick the Defender as the favourite to win any America\u2019s Cup match \u2013 that is a large part of why the trophy is so unique and elusive \u2013 and this cup cycle looks to be no different. No matter what secret developments arrive for the challengers between now and the start of the America\u2019s Cup itself in March, the Kiwis are the clear team to beat.
\nThe crew
\nThere are few sailing partnerships as successful, and apparently as near-telepathic, as Pete Burling and Blair Tuke. The multiple 49er world champions, gold and silver medallists and America\u2019s Cup holders have an uncanny ability to get the best out of every boat they step on, so it\u2019s no surprise that while Burling steers the AC75 Tuke will be flight controller.
\nThe rest of the squad reads like a who\u2019s who of yachting, from CEO Grant Dalton to a design team that includes Guillaume Verdier, not least sailors like Glenn Ashby and Ray Davies.
\nAdditional reporting by Toby Heppell.
\nThe post How the America\u2019s Cup contenders compare going into the Prada Cup appeared first on Yachting World.<\/p>\n","protected":false},"excerpt":{"rendered":"
The three challengers will start their assault on the America’s Cup this week as the Prada Cup gets underway. Matt Sheahan assesses each of the teamsA spectacular skyward launch for American Magic\u2019s Patriot during early trials. The focus of these … <\/p>\n