The Bucs trail Hudsonville in the league race.
Pitcher Yogi Hang pitched four scoreless innings until Grandville scored three runs in the fifth. Kylie Masko entered in relief and shut down the Bulldogs for the save.
Morgan Hill cracked a two-run homer in the third to lead Grand Haven to a 3-0 lead.
The Bucs broke the game wide open with a six-run seventh inning, sparked by doubles from Hang and Pita Messer. Mikayla Gronback batted 3-for-4 with two RBIs and Jordan Buckingham had two hits and three RBIs.