Vette posted a 14.4-point heat total in the u18 final to upstage event favourite Caleb Cutmore (Raglan), who had been on fire all weekend.
Vette surfed a seamlessly ridden left-hander early in the heat and backed that up with a sharp two-turn combination on his backhand to hold the lead for much of the final and through to the final siren.
Cutmore finished runner-up, just holding off Taylor O’Leary (Muriwai) in third place with Myka Black (Christchurch) fourth.
The u16 boys’ final was the most hotly contested of the day.
Tom Butland (Taranaki) and Tom Robinson (Whangarei) capitalised on the right-handers rolling down the beach.
Both scored excellent rides, Butland coming out on top 15.97 to 15.71.
Gisborne’s Vette opted to surf his forehand on the lefts and took an early lead in the final with a pair of sevens before being pegged back and ultimately finishing in third place ahead of Myka Black (Christchurch).
Christchurch surfer Ava Henderson, 14, won both the u18 and u16 girls’ divisions.
South Island Grom Series winners —
U18, boys: Luke Rogers (Dunedin).
Girls: Ava Henderson (Christchurch).
U16, boys: Reuben Lyons (Kaikoura).
Girls: Ava Henderson (Chch).
U14, boys: Jack McKenzie (Chch).
Girls: Misha Peyroux (Dun).
U12, boys: Sonny Lyons (Kaikoura).
Girls: Tessa Gabbott (Dun).