"We slacked off in the second half after starting off well. We've still got a lot to work on and there's still the Top Four to aim for," he said.
Hamilton, who shared the Super 8 title with Hastings Boys' High School last year, turned down two easy three pointers in the first three minutes and were rewareded for their patience when No 8 Dion Keogh scored a pushover try in the fifth minute.
Napier opened their account with a 13th minute try to Leo Thompson after good work from fullback Max Anderson. The visitors took the lead in the 24th minute when busy No 8 Luke Russell scored from a lineout drive.
Superb patience and ball retention resulted in Napier tighthead prop Patrick Teddy scoring in the 33rd minute. Second five-eighth Keegan Christian-Goss added the conversion and the visitors led 17-5 at the interval.
Five minutes into the second half Hamilton turned down a three pointer attempt and opted for a scrum. From a set piece move centre Josh Calvert scored and Murray added the conversion to have the hosts trailing 17-12.
Fijian winger Leweni Mocekaca raced 64 metres for a try to tie the game up in the 46th minute. A 54th minute penalty from Murray had Hamilton ahead for the first time at 20-17.
Napier regained the lead in the 59th minute when flanker Sam Henderson exposed some fragile defensive work from Mocekaca to score in the corner. At the business end of the clash Hamilton retained possession well and put Napier under enough pressure which resulted them in conceding a penalty which proved to be the killer blow.
While Leo Thompson deserved the player-of-the-match award he must have been pushed close by Teddy who had a massive workrate. He carried with purpose and tackled tirelessly.
Captain Thompson and Russell also proved why they were selected for the Hurricanes under-18 camp last month.
Captain and blindside flanker Tom Martin, Keogh and lock Josh Lord were inspirational in the Hamilton pack. Halfback Cortez-Lee Ratima was just as classy as he was in the previous week's 26-0 win against Hastings Boys' High School.
"We knew we had to hold on to the ball. We stuck to our structures and weathered a tough storm," a delighted Martin said afterwards.
Scorers:
Hamilton BHS 23 (Dion Keogh, Josh Calvert, Leweni Mocekaca tries; Demante Murray 2 pens, con), NBHS 22 (Leo Thompson, Luke Russell, Patrick Teddy, Sam Henderson tries; Keegan Christian-Goss con). HT: Napier 17-5.