Now that we have the four, second generation of AC75 America’s Cup boats together on the waters of the Hauraki Gulf, a new round of who-has-got-it-right can commence.
A common factor this time round is that all four are using the same piece of water, so comparisons should be easier, even allowing for the no training together rule.
Another common factor is that they have all gone for some fairly big design changes, not least the defenders, Emirates Team New Zealand.
Despite trying to convince everyone that they had a fast boat with their first effort, mainly based on their percieved advantage of drawing up the new AC75 rule. It now looks like they decided, at quite an early stage (three months in) that the opposition was not looking so bad after all.
But it was still rather suprising to see how radically ETNZ changed their basic design thoughts . . . if their first effort was so fast!
It seems that the AC36 teams have all gone some way to a common set of features . . . particularly the pronounced flared bow and deep, wide skeg hull, and removing the bustle.
This conversion to a new set of norms seems to indicate that their massive data banks were all saying the same thing . . . you got it wrong!
Thus, American Magic and Ineos Team UK dumped the scow style flat bottoms and snub bows, while Luna Rossa and ETNZ took their skiff light designs to new levels.
All ending up on the same page with minor but no doubt important variations.
While we are in awe of the thousands of design hours and data crunching expended, it rather spoils the effect when we see the undignified haste of Luna Rossa to add the ridge or ‘chiglietta’ to their skeg.
Luna Rossa obviously thought it an important enough feature to take their newly launched second boat off the water for a week to add it, apparently when news of the Kiwi boat development reached them. So much for all that data mining!
Such a change, after they had declared the boat and launched, brings them into the 20% maximum allowed change rule and will count if they need to change anything else.
The American Magic team kept their second hull to a more integrated design, but still a world away from their initial thinking.
Going with the ubiquitous deep skiff style, but without the broad, flat skeg base which is such a feature on the British and New Zealand second hulls.
Also, the skeg of Patriot does not continue the length of the hull to the rudder position as on the other three boats, but rather fades into the hull.
This makes the American boat profile a rather stand-alone configuration from the other three, with their distinctive full length skegs.
Although ETNZ have added a neat variation to that coda with the a sweeping reduction to form a mount for the rudder on Te Rehutai.
With the final hull designs now fixed, except for small changes (20%) allowed by the AC75 rule from now, development continues apace with the foil fairings, wings and flaps, and some improved fairing of the supplied operating arms.
While the British boat, Britannia 2, rolled out with the most radical makeover – more a clean sheet of paper job – after they had already flagged their thinking with a stick on skeg while down in Cagliari.
They then went all-in with the most sculptured skeg to hull design, and perhaps not wishing to repeat the weak effort in AC35, are working hard on their foils.
The Britannia 2 skeg is a sharp-edged design, helping to maintain the airflow separation, while the rounded skeg designs use the ridge or ‘chiglietta’ to the same effect.
The Brits rolled out Britannia 2 with wide chord, cranked foils, and flaps, developed by their F1 motor racing partners, but have since sailed with a mix of cranked and single anhedral foil configurations.
There has been some talk of using different foils on each side . . . one to get up and go (more area on the port foil) from the start and ones with less drag for 50% of the downwind / upwind leg!
Deck layouts have also been optimised following some actual sailing experience.
The deck sweeper mainsails restrict crew movement, and some thought has gone into avoiding likely obstruction/trip points, and in improving visibility for the helm.
There has also been more thought applied to the intergration of the hydrodynamics when in the water verus the aerodynamics when up and foiling.
How important this will be in the cut and thrust of competition we have yet to see.
Clear speed runs and tacks are one thing . . . slick manoeuvres in the heat of a close contact race is another.
So, we are now ready for the final round of training/tuning runs, all carefully keeping clear of one another as the Protocol requires.
Everything is now coming together for the only remaining Preliminary Regatta, the Auckland ACWS and the Christmas Race.
Scheduled to start on the 17 December, if they have managed to collect the entrance fees and produce the NOR.
Are we there yet? Not by a country mile . . . this is the America’s Cup!
Related Post:
First day on the Hauraki Gulf for ETNZ and new AC75
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