"It was awesome," said Newdick.
"I've even got cramp. I was holding on that much.
"I can't believe it. It's a long time coming."
Waitotara's Duncan Wilson came second in the Group As at Wanaka in a swift turnaround from his massive prang at Round 5 in Shelterview where he knocked out the light fixtures on top of a trackside pole.
In doing so, Wilson upset Australian Paul Gaston's hopes to catch Newdick, with the series runnerup left to rue a crucial wrong turn.
Once again, multiple-time Superboat national and world champion Peter Caughey proved his class, winning the round to retain his 2013 title and claim his ninth national championship overall.
Sitting third in the series, Australian Phonsy Mullen, like Gaston, took a wrong turn to drop out of contention, leaving Caughey to fight it out with Hastings' Graeme Hill to decide the round and the title.
Caughey's 49.7 second final drive in the Top 5 was three seconds quicker than Hill and sets the Cantabrian up for a strong tilt at a seventh world championship in Oregon and Missouri in August.
Current world champion Leighton Minnell had hoped to get up for third in the series in Wanaka, but a starter motor problem in the Top 5 eliminator put pay to those hopes, leaving him fourth overall.
Wanganui's Peter Huijs finished sixth in the Superboats series, while Rob Coley came eighth.
Results
Round 6, Wanaka.
Jetpro 400: 1. Hayden Wilson (Wanganui); 2. Warren Farr (Taupo); 3. Ollie Silverton (Hamilton).
PSP Group A: 1. Sam Newdick (Hamilton); 2. Duncan Wilson (Waitotara); 3. Bevin Muir (Thames).
Suzuki Superboat: 1. Peter Caughey (Christchurch); 2. Graeme Hill (Hastings); 3. Greg Mercier (Australia).