For CHB, James Hooper-Smith took 3-35 while Angus Schaw, Blair Tickner and Charlie Robson claimed two each.
In reply, CHB ran out of steam at 117 in 40.1 overs with just Angus Schaw putting his hand up with 47 (48) but the rest, excluding Jake Wakeling (19), didn't want a bar of it.
"We batted like extra crap but we were up to it. That's what happens in finals cricket," a relieved Diack said.
"This time of the year runs will win you the game," he said, mindful a talented CHB had "come to play" but NTOB "wanted it more".
"We wanted to beat the best," Diack said, adding Tickner and Dom Thompson had returned from their South Island universities to help CHB.
Diack agreed CHB should have kept them to around 100 runs but had dropped several catches, something NTOB had done as well.
Christian Leopard and Jayden Lennox got three wickets each while Liam Rukuwai and Stevie Smidt took two apiece to save the blushes.
On the adjacent wicket, Havelock North beat The Station Napier Old Boys Marist (NOBM) by 122 runs.
Having won the toss, Havelock captain Jared Priest batted as the villagers posted 330-5 in 50 overs.
No3 Graeme Tryon scored 108 runs, his fourth century and the second in a row.
No4 Will Hilton added 62.
NOBM could only manage 190-7 in 50 overs with veteran Daniel Drepaul scoring 57.
Explained Priest: "They [NOBM] were docked two overs for a slow over rate, which was pretty generous because it should have been four."
Tryon and Ruan Markram claimed two wickets each.
He was mindful the Bevan Pollock-skippered NOBM had the New Zealand Club Championship finals on their mind.
"In the end it felt like they were going through the motions and it seemed all too easy."
In Priest's opinion, "the best two teams" will play the final even though Havelock North were third qualifiers, a rung below NOBM.
