But it was all too easy at times for the team enjoying playing at home under the roof.
Harbour coaches Liam Barry and Jeff Wilson must wonder what more they have to do to get their side a win.
On the other hand, Otago looked assured with the ball in hand and gained plenty of quick ball which had Harbour back-pedalling.
The home team showed some attacking ability after it had failed to score a try in its previous two games.
The goalkicking, so much under the spotlight after the botched kicks by the likes of Morne Steyn last Saturday night in the stadium, was not bad, though the pressure was at a far lower key.
With the win Otago went up to third on the championship table and face a crunch game against Tasman on Sunday, again at the stadium. Harbour takes on Southland back home at Albany.
Otago halfback Fumiaka Tanaka kept up his rich form, while flanker Gareth Evans scored two tries and roamed all day. Tighthead prop Liam Coltman was also busy.
Harbour's best was halfback Bryn Hall and hard-working lock Chris Smith.
The home team made a great start to the game, scoring a try after five minutes.
They won a lineout 10 metres out and rumbled the ball up with Evans crossing.
They backed that up five minutes later with Smith crossing after he dragged himself over the goal line thanks to a nice ball from Ellison, which looked a metre forward.
Harbour's inability to hang onto the ball was costing it big time, and any time in the opening it had an opportunity it would drop the ball.
Hall scored a try for Harbour right on halftime, burrowing over after a period of Harbour pressure.
Otago 54 (Gareth Evans 2, Ben Smith, Buxton Popoali'i, Marshall Suckling, Rob Verbakel, Glenn Dickson tries, Dickson 3 con, 2 pen, Hayden Parker 2 con, 1 pen)
North Harbour 25 (Bryn Hall, Vili Fihale, Manu Leiataua tries, Hall 2 con, 2 pen)
Halftime: 27-10