"The New Zealand marine industry has benefited hugely from the new one-design rule, which allows components to be made in any country as they're outside the country of nationality rules," he said.
"New Zealand companies were then able to compete for the work of teams outside New Zealand, and our reputation as the world's best boat builders came to the fore."
Oracle Team USA chose to build their AC50 in New Zealand, Busfield said.
New Zealand's unique training programme for boat builders had set the bar standard high, he said.
Auckland-based Southern Spars built the hull and wing for Team New Zealand.
Further north in Warkworth, Core Builders Composites built Oracle Team USA and produced boat components for SoftBank Team Japan and Team New Zealand.
"This significant change to the rules meant that the teams were free to build their yachts and source the best products anywhere in the world," Busfield said.
Kiwi firms C-Tech and Cookson Boats were also at the forefront of AC50 innovation.
Southern Spars, C-Tech, Core Builders, Cookson and other NZ Marine Industry Association members supplied sets of hull, deck, bow, pod and beam tooling, with moulds and tools designed to ensure parts were identical and in-line with one-design rules.
Busfield is currently in Spain promoting New Zealand's marine expertise.