The advantage - and time - gained is enormous. In a traditional gybe, the boat slows, dropping its hull deeper in the water. In the AC72s, the slowdown if a boat comes off its foils and touches the water is considerable - at least halving boat speed.
Team NZ are said to be pulling off some gybes at about 30 knots - a huge benefit if the opposition are struggling round a mark at half that rate, as the Italians are. Team NZ are regularly pulling off foiling gybes at considerably more than 20 knots when they get it right.
MacBeth said it was difficult to tell which of Team NZ or the two Oracle boats was going faster but said Oracle's top speed was "about 44 or 45 knots" - the same speed Team NZ cracked to set the speed record last week.
MacBeth also said that he thought the two Oracle boats were still sailing on the old, non-compliant rudders though there were reports last week that Oracle had begun training using the compliant rudders that were the subject of "Ruddergate" before and during the start of the regatta.
As a sailor who's done it both ways - preparing for a regatta with two-boat testing, as Oracle are now doing, and sharpening up by racing other challengers - he said having the two boats was "a great asset".
"It allows us to practise our pre-starts and I don't see Team NZ or Luna Rossa offering to come over and train with us. I think it is good [training with two boats] when so much depends on it and it is maybe more important [than racing against distant opposition] but, at the other end of the stick, development time in making the boat go faster is also very important and you have to balance your time."