Its all in the rules: https://www.americascup.com/en/news/2583_KNOW-THE-ESSENTIALS-AMERICAS-CUP-RULES-101.html
6-24 kts, taken as a 5 minute average between 8 and 3 minutes before the start.
I feel for TNZ on this one, but the damage could have been much, much worse. I'm sure they will be back out there tomorrow.
The safety of the one design aspect of the boats certainly shone through yesterday, but I still don't entirely agree with this. The one design beams I'm okay with, the one deisgn #1 element on the wing I am sort of okay with, the rest not really. FYI the #2 element (trailing edge flap) and wing controls are not one design and open to interpretation. My understanding is only the structural main element mast is really strictly one design. I think TNZ would have gone with more margin in the hulls rather than relying on Oracles lower volume prescribed hull design, if given the flexibility there. Would it have saved them? No, they were on the foils going down the mine and it was too late by the time the bows hit. If anything a bigger bow section would have hurt. The emphasis on the controls and foils clearly favor Oracle, who have more experience than any other team besides the less well funded TNZ campaign. I understand the AC is never very fair but I preferred the run what you bring and your wallet can swallow over this glorified AC45F racing. Frankly the same level of racing could be had with a box/open rule AC45F.
I'm really disappointed Oracle sailed in the initial LV challenger series. I think that was rather unfair and unsportsman like. I'm also not okay with the 1 boat rule for the challengers. That clearly favors Oracle whom I suspect have a second boat in the shed just in case (with the amount of money thrown around, why wouldn't you?). One designing the major structural elements of the boat made it pretty feasible that a second boat could be built on the cheap. This puts Oracle in a position to effectively force races in conditions that are otherwise very hairy and marginal, yesterday wasn't deadly but it was a bit marginal. By the time the challenger gets through to the finals, they will likely have done some damage to their race stead and be operating at a higher weight as a result. Far from ideal if it goes light, but good for Oracle!