The Seagulls scored a four-point win, defeating Terang Mortlake, 3.5 (23) to 3.1 (19).
Terang Mortlake kicked 3.0 to 0.2 with a howling wind in the first half of the grand final at Friendly Societies' Park.
But the Seagulls surged when it was their turn to kick with the wind, with Robbie Hare kicking 3.1 in the final 20 minutes, including the match-winner with less than two-and-a-half minutes remaining.
The Seagulls were impressive with many of their recruits, Jaxson Barham, Aaron Shields and Jackson Hollmer doing well. Unheralded players like Ash Rendell in the middle, ruckman Adam McCosh and tough-nut Aidan Leishman were also good contributors from an even team effort.
Terang Mortlake was best served by Jake Meade up forward with two goals, Damian O'Connor with one goal from the midfield, Chris Baxter in defence, and midfielders Jason Lee and Danny Craven.
The Seagulls collected $4000 for winning the round-robin competition. They and the Bloods won through to the grand final after narrowly finishing ahead of Camperdown.
The result gives both clubs confidence heading into the season proper after missing the finals last September.