A sixth round-robin was called off due to time constraints but by then Kerikeri had an unassailable 5.5-point lead over closest rivals Auckland Grammar.
The three Kiwi schools also managed to wrest the country trophy back off the Australians. The final points tally was New Zealand 27, Australia 13.5.
The latest trophy built on the Kerikeri team's fifth national title in a row, won at Algies Bay in April.
"That was massive," Smith said. "We're got a really strong group of sailors at the moment."
The school's open team is coached by former Kerikeri High student turned professional sailor Reuben Corbett.
Meanwhile, a Kerikeri open team also cleaned up in the Springs Regatta on the same dates at the same venue. Five schools took part in the learners' regatta, with the Kerikeri open team winning 24 races. The second-placed team won 14.
A Kerikeri girls' team came last of the five but it was only their second season and they had "improved tremendously", Smith said.
Godbert said one of the key factors behind Kerikeri's success against bigger and better resourced schools was that it started its sailors young and had a wide age range in the squad. One of the pairs in the Springs Regatta was Nik Black, 18, and Emilie Jones, 10.
"That means the young ones can sail with the top skippers and build up their skills over several years.
"Other schools might have a strong team of Year 11 or 12s, but after a few years they're gone."
Kiwi sailing champion Andrew Murdoch started in the school's squad when still in primary school, Godbert said.
Also on Kerikeri's side was the size and depth of their squad. They had 20-30 members at any one time while few schools had more than eight. The squad also had a core of parents who put in a lot of time and energy, and a supportive school, he said.
The venue, and boat type for the Inter-Dominion regatta alternates between New Zealand and Australia.
This year's event was in 4.2m boats called 420s; next year it will be held in Australia in Pacers.
