Prop Solo Baleinaikasakasa made a thundering run to set up a further try for Paula Lu’au in the 13th minute, and captain Jarrel Tuaimalo-Vaega made it 18-0 just before halftime.
In the second 30-minute spell, flanker Joseph Paiali’i finished a flowing 50m move for a bonus-point try, Lu’au added another midway through the half and sub Tariec Mulitalo scored just before the end.
Meanwhile, it took 23 minutes for Westlake to gain the upper hand against Harrow, with loosehead Alex Va’aia finally burrowing his way over.
Westlake No 8 Travis Findlay made some searing breaks to set the platform for further dominance and centre Ashton Falloon added a second try just minutes later.
Then from a stunning backline move, Werner Van Staden left a trail of defenders in his wake for a further try.
On a day when kicking was troublesome for everyone, fullback Brody Good landed an excellent conversion from Van Staden’s try, straight into the teeth of the wind, for a 17-0 halftime lead.
Much of the second spell was deadlocked, but five minutes from fulltime, Westlake halfback Lee-Hanru Greyvenstein scored a bonus-point try in finishing a slick blindside move for a 22-0 lead.
Westlake defended stoutly afterwards, though Harrow managed to score with the final play of the game.
On Tuesday night (NZT), Kelston face Zimbabwe’s Zambezi Steelers and Westlake clash with Welsh champions Llandovery College.