The game was tied 46-46 with 8:39 left when Mike Prestileo scored and then Cain hit his three straight three-pointers before Prestileo capped the 14-2 spurt with his own three-pointer with 6:23 to play giving WPI a 60-48 lead.
Cain finished the game with 16 points, as he hit five-of-six from three-point range.
Prestileo, who finished with a game high- 21 points, started off the game with WPI’s first eight points and the Engineers led 8-7 with 14:35 left in the half.
The Engineers (17-6, 6-3) led 34-29 at halftime.
Dan Sheppard led Coast Guard (3-17, 0-10) with 20 points, 11 rebounds and five blocks while Jason Nelson added 14 points and Kevin Edes 10 point for the Bears, who dropped their 12th straight.