Stewart picked up four wickets for 46 runs off his10 overs while Kapene scored 24 of the Bay’s 50 runs.
Northland take on Counties Manukau in the two-day final, starting today (weather permitting) after Northland beat Bay of Plenty Coastlands in the top-four semifinals and Counties Manukau downed Hamilton.
Northland were teetering at 121-9 but what turned out to be match-winning last-wicket partnership of 46 between Quinn Pooley (39no) and Alex Gordon (20 off 23 balls) got them to 169.
Coastlands were dismissed in 37.4 overs for 123. Daniel Price (35) and Marcel Collett (27) were the pick of their batsmen.
All the Northland bowlers were tight and accurate, backed up by good fielding.
Counties Manukau made 231 then dismissed Hamilton for 175 for a 56-run win.