Rennich got the Owls on the board first in the eighth minute, and Morgan Remington tallied what would prove to be the game winner about three minutes later.
The Owls had seven different goal scorers and eight players tallied at least one point.
Madison Taylor scored a late goal for Maritime to spoil the shutout.
Westfield out-shot the Bucs 24-7 in the match. The Owls improve to 6-3-1 overall and 3-1 in the MASCAC. MMA falls to 1-8 and 0-4 in the league.