There is one round to go before the semifinals.
HSOB put on a 56-run opening stand before left-arm spinner Matt Crampton struck twice, including the dangerous Carl Shaw (27), caught by Richie Needham, with the score at 74.
Crampton maintained his early season form to take the third wicket, bowling fellow South African Bruce Kerr (24) with Pirates on 93.
Talya Hollis chipped in with the wickets of Scott Tallott and Glen Udall, with assistance from Sam Patterson and Crampton, and Baxter Mackay mopped up the tail to finish with 3-22.
But there was no removing Tallott, who, on this form, has made HSOB even stronger contenders for the title.
Pirates lost three wickets for 35 runs, leaving skipper Dane Thompson and Crampton to rebuild the innings with a 48-run stand.
Kulaar broke the partnership when he bowled Crampton for 13. He then knocked over the stumps of Thompson (38).
Patterson wagged the tail with 21 off 28 balls only to become another Kulaar victim.
OBR rolled Boys’ High for 107 and were never troubled in their chase.
An opening stand of 40 from Kieran Venema and Craig Christophers came to an end when Venema (17) was bowled by Jacob Colbert.
Christophers and Timoti Weir then joined forces for an unbroken partnership of 68.
While Christophers, with 32 of 41 balls, was content to steadily construct his innings, Weir took the direct route. He hammered one six and six fours on his way to 41 from 29 deliveries.
Christophers and fellow senior team member Ian Loffler earlier led the OBR attack — Christophers bagging 4-12 and Loffler 3-15 in what one teammate described as “awesome bowling”.