Home team prop Tasman Soanai opened the scoring with a try to which PNBHS replied with a penalty to fullback Sam Coles. PNBHS took the lead with a try to left wing Aaron Chistenson just before halftime.
PNBHS led 11-10 and spent considerable time in Napier's half entering the last minute before Berkett kicked the big one with perfect timing on the wind behind.
It was also a big day for prop Gus Brown, making his 40th Napier 1st XV appearance across three seasons.
It was second time around for the two schools, with Napier having scored a last-minute try in June to beat PNBHS in the schools' annual Polson Banner match, this year a feature of the school's 150th anniversary celebrations in Napier.
Ratcliffe's coaching career goes back almost 30 years to when he applied at the age of 22 to be the Hawke's Bay union's development officer, for 150 schools and at least 25 clubs from Akitio in the south to Nuhaka in the north. He coached the Hawke's Bay Magpies for three years, starting in the second division in 2004, followed by a title-winning unbeaten run a year later, and for one year returned to the top level in an expanded NPC Division one in 2006.
As NBHS coach for five years, he described Saturday's satisfaction as "more relief", after three weeks off, reckoning it was not the best performance of the year for a side he believes has what it takes to claim the national title.
"Been in the game a long time, you lose some you thought you should have won, and win some you could have lost," he said. "On another day it could have been a win to Palmy."
Meanwhile, in Hawke's Bay secondary schools finals, Hastings BHS Red beat Napier BHS Hostel 43-5 to claim Division 2 honours, and Hastings BHS Div 3 Red beat Lindisfarne College 21-10 in the Division 3 match.
The Division 1 final, which doesn't include the 1st XV who play in such wider competitions as Super 8, is expected to be a curtainraiser to the Hawke's Bay Magpies' Ranfurly Shield defence and Bunnings NPC match against North Harbour at McLean Park, Napier, on Saturday.