Oracle have released details of the foil control system that was central to their defeat of Team New Zealand in the America's Cup final.
While there has been much speculation about Oracle's improved foiling as the final evolved, coming back from 8-1 down to beat the Kiwis 9-8, the latest details suggest the system was completely legal.
The system allowed them to have precise control of the daggerboard rake, bringing added stability.
They filed a public inquiry to the measurement committee to make sure their developments were above board and gained approval on August 8, a month before the final began.
Team New Zealand's questioning of the system drew a blank from the measurement committee and the International Jury ruled that the Kiwis protest was too late, coming right on the eve of the final. They also felt it would not have succeeded if it had been filed on time.
Under the system skipper Jimmy Spithill used buttons on the catamaran's steering wheels to rake the daggerboards forwards and backwards in precise spaces of 0.5 degrees.
The developments are revealed on the Cupexpereince.com website.
They say the system, which used a simple "mechanical feedback" loop, allowed Oracle to be much more exact with their daggerboard movements than the manual system employed by Team New Zealand, which suffered variances depending on the hydraulic pressure provided by the grinders.
Oracle admit they were behind the Kiwis with the art of foiling, particularly upwind. That was a key to Team New Zealand gaining the early advantage in the final.
As the Americans refined their system during the final, their foiling became much more effective. Ultimately they were far superior to Team New Zealand on the upwind leg and that was the winning of the cup.
Oracle also admitted to copying Team New Zealand's successful rolling gybes, another area where the Kiwis gained early supremacy with gains on each tack. That advantage was negated as Oracle increasingly mastered this key piece of crew work.
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