Bottom line: it was perfectly legal. Cup rules stated foils had to be controlled manually and there was nothing resembling electronic or computer-controlled guidance in Oracle's system.
"It's not an electronic system," says Mike Drummond, a former head of Oracle's design team, of the button helmsman Jimmy Spithill pushed to activate USA's foil-assist system. "It's very similar to turning on a light switch. It just sends some fairly dumb current or voltage down the line, which at the end of the wire opens up a hydraulic valve. The foil moved and when it moved half a degree it closed the valve again."
The major difference to Team New Zealand's system was the accuracy provided by the half-degree pre-sets, which eliminated the variations in hydraulic pressure that came from their grinders.
But if "Herbie" was so crucial, why was USA so far off the pace early in the regatta? The major factor, says Drummond, was the lack of co-ordination between replacement wing trimmer Kyle Langford and Spithill following Dirk de Ridder's suspension for cheating.
The relationship between helmsman and wing trimmer was similar to two people attempting to drive a car around a corner at high speed, explained Drummond.
"You've got the steering wheel and I've got the accelerator. As the car drifts outside the corner with a bit of understeer, I could let the accelerator off or you could turn the wheel or we could both do a bit. I'm sure after a year's practice we'd be pretty good at it, but after a day's practice we'd be lousy.
"Oracle didn't sail their boat as well [to begin with]. Their wing was needing to be trimmed a lot more and tactically they made some mistakes. They didn't start as well. There was a whole bunch of things but I don't think foiling was to blame for their performance in the first half of the regatta. It was almost every other aspect of their sailing, and when they eliminated their mistakes and the co-ordination between the wing trimmer and the helmsman improved markedly, and when they developed their upwind foiling quite rapidly, finally the potential of the boat came through.
"Their programme was at fault for not preparing them well enough for the Cup but they were good enough to improve during the Cup to pull off a miracle, really."
Hydrofoils are not new. They've been around for a century. However, their successful use in giant catamarans is revolutionary. Boats on foils increase in speed and continue to lift out of the water until they eventually fall off the foils and crash back into the water, so the challenge all Cup syndicates faced was finding a way of keeping the foils in the water. Both Team New Zealand and Oracle found a solution, inventing self-regulating foils. The technology they employed is already filtering down to the recreational yachting sector.
Auckland boasts three 33ft cats capable of foiling just for fun, says Drummond, who owns one of them, SL33. It was used by Team New Zealand as an early training boat.
The rapidly developing art of foiling should again be a crucial factor when the Cup is next up for grabs in 2017. How crucial will depend on rules that have yet to be set. The stated desire to increase participation by driving down costs could see an area that would otherwise be a key technological battleground levelled out.
But if the development cycle is allowed to take its course, we may well look back on the staggering developments of 2013 with a bit of a chuckle.
"Any time a new technology comes along you think 'wow, this is the future'," says Drummond. "Then you turn around in four years' time and look back and think 'my God, how crude were we back then?' Somebody is going to come up with a better idea and who knows where it will end up?"
