"We trained to not make mistakes, so we've got to cut the errors out," said the lock.
Otago led 14-13 at the half, but that came with some luck. Prop Craig Millar latched onto a Tom Franklin offload to sprint 25m for the opening try, but there was enough doubt to say it was a forward pass. First five Fletcher Smith kicked well, both out of hand and off the tee, where he was five from six, along with making a trysaving tackle on Vui.
North Harbour were dangerous on attack at times, but their passing was often shoddy and No 10 Bryn Gatland twice committed the cardinal sin of failing to find touch from penalties. However, they did reduce the margin to one when Michael Little made a break to set up his midfield partner Matt Vaega, who looked likely for most of the match.
Otago hooker Sam Anderson-Heather's 44th minute try was critical as that halted some of Harbour's momentum, both teams having entered the second spell with intent. And though Brandon Nansen made an emphatic impact off the bench, both aerially and with the ball, the errors kept mounting for North Harbour.
The pleasing sight was replacement back Marty Swart making his return from two seasons of knee reconstructions for the visitors.
Otago travel to Christchurch next Saturday for a crossover derby with Canterbury, while North Harbour are back at home to Southland the following day.
Otago 24 (C. Millar, S. Anderson-Heather tries; F. Smith con, 4 pens)
North Harbour 13 (M. Vaega try; B. Gatland con, 2 pens)
HT: 14-13