Boro took an early lead through Tom Craddock but the Seadogs were level inside 15 minutes with a goal from Tony Hackworth.
It was fairly even until the final quarter that Boro won the game with three goals inside ten minutes. First David Wheater made it 2-1 before subs Harrison Davies and Callum Reveley made the game safe.
Boro will play Whitby in the final on a date to be decided.
Team:
Knight, Cattermole, taylor, Hines, Wheater, Grounds, Lemaire (Reveley), Kennedy (Radcliffe), Craddock, Peacock, Johnson (Davies)