The Sailors led 20-18 at halftime and 31-26 after three quarters, the put the tight victory away with a 17-16 edge in the fourth.
Brooke LeRoux paced the Sailors with 19 points, Megan DeLong added 11 and Riley Rosenthal and Olivia Sobczak each chipped in seven points.
Mona Shores improved to 9-9 overall and 6-4 in conference play.
Muskegon, which did not report its statistical leaders, dropped to 11-7 overall and 7-3 in the conference. The Big Reds now trail Jenison and Reeths-Puffer by one game with a week left in the regular season.