Rosmini sailed to victory, thanks to an impressive showing from Campbell Stanton and Francesco Kayrouz, who held off Otumoetai's James Barnett and Joel Kennedy.
Barnett finished third behind the Rosmini boys in the Year 8 individual honours and overall best sailor categories, but headed the field in the race for top Tauranga sailor.
Other individual golds went to Greta Pilkington from Helensville School (Year 8 girls), Monty Alderson of St Kentigern Boys' School (Year 7 boys) and Helena Sanderson from Kerikeri High School (Year 7 girls).
Barnett, 13, knew it was going to be a major challenge to beat the Rosmini boys in the Optimist-class boats.
"I am definitely happy with how I performed, though," he said.
"On the first day [Saturday] we had a lot of wind and very challenging conditions.
"The next two days were lovely, as we had medium breeze and sunshine. The school [Otumoetai] will definitely be happy with second place as it was the first year of sailing at the AIMS Games."
The regatta was ideally timed for Barnett to get some serious match racing in before he represents New Zealand at the Asian Optimist Championships in Qatar in mid-October.
"This regatta was quite important because over winter we haven't had any regattas so it is really good to get warmed up and get ready for my major regatta," he said.
New Zealand are sending 10 of the top 20 sailors in Optimist overseas to the Asian regatta. The competition will be tough because Asian teams such as Singapore are reasonably high up in the world rankings. Barnett says he would quite like to follow in the footsteps of his oldest brother, Sam, in the two-handed classes such as the 420 and 470, and perhaps one day follow a similar path to fellow Tauranga Yacht Club member Burling.