The power of the Waitaki pack - in which big lock Don Lolo, openside flanker Jake Rhodes and prop Regan Smith stood out - gave its backs plenty of possession.
Kane McLauchlan was an astute first five-eighth, backed by an enterprising fullback in Jamie Robb.
Their influence allowed the power running of midfielders Levi Fogarty and Anthony Wetere-Sweet to savage the St Kevin's defence.
Quinn McNab, Harry Lanauze and Ash Miller were the pick of the St Kevin's pack, while wingers Michael Hannigan and Jack Allan showed pace but had few opportunities.
Tim O'Malley, at first five, was hindered by sluggish delivery from Jack Daly behind the pack.
Marc Fox (Waitaki) and O'Malley swapped penalties in the first six minutes before O'Malley put St Kevin's into a 6-3 lead after 15 minutes.
Waitaki hit back with tries to left winger Dean Fenwick and fullback Robb.
In the second half, Waitaki scored four further tries to Fenwick, McLauchlan and replacements Stephen Butler and Jake Greenslade.
First XV
The scores
Waitaki Boys' 37
Dean Fenwick 2, Jamie Robb, Kane McLauchlan, Stephen Butler, Jake Greenslade tries; Marc Fox 2 con, pen
St Kevin's 6
Tim O'Malley 2 pen
Halftime: Waitaki Boys' 15-6.
Written by Terry O'Neil
