Voyce finished the race in 2h 43m 29s, two minutes clear of Clark.
A strong 30km mountain bike leg through the Whakarewarewa Forest proved crucial for Voyce, as he reeled in the runaway Whakatane star.
The 50km race included a 9km kayak on Tikitapu (Blue Lake), 30km mountain bike ride and 11km run in the Whakarewarewa Forest.
Last year, Voyce also had a chance to win before Australian Jarad Kohlar bet him over the last kilometre.
"Last year's finish gave me plenty of motivation and also the nous that you've got to dig it in right to the end and you can't be complacent at any stage, " he said
Clark, who is focusing more on ironman racing this year, was philosophical about the result.
"He's obviously been putting some serious work into his mountain biking and he's been chasing a win here for a long time so I'm pretty happy for him (Voyce) to take it out," he said.
"It's also given me a bit more incentive to come back and win it as well though."
It proved a vintage day for Nelson athletes with Elina Ussher taking out her third title in the women's division, beating 2013 winner Simone Maier (Wanaka) by 35 seconds.
"I had a pretty good paddle and was leading after the kayak and then I just went as hard as I could for as long as I could," Ussher said. "I knew that the young, fast, pretty girls were chasing me pretty hard."
Ussher crossed in 3:07:52, with Maier clocking 3:08:27 and Emily Wilson (Cambridge) third in 3:20:09.
Clark wasn't the only Whakatane athlete to feature yesterday, with 17-year-old Hayden Wilde finishing fourth in the men's race, only 20 seconds adrift of five-time Coast to Coast winner Richard Ussher.
- Results from feature 50km race:
Men: 1 Trevor Voyce (Nelson) 2:43:29, 2 Sam Clark (Whakatane) 2:45:37, 3 Richard Ussher (Nelson) 2:51:03.
Women: 1 Elina Ussher (Nelson) 3:07:52, 2 Simone Maier (Wanaka) 3:08:27, 3 Emily Wilson (Cambridge) 3:20:09.