Kamper was spent at the end of the marathon but took the win as an initiation of sorts that he was ready to graduate to endurance distances in open sea swimming.
For his troubles, the year 10 pupil received a medal and the promise of having his name engraved on a trophy for "wetsuit" swimmers.
Almost half the field opted not to don wetsuits but Kamper said wearing one made little difference.
The Napier Aquahawk Swim Club member, who receives open sea coaching from his mother, Karen, has pencilled in the Masters 17.5km at Lake Taupo next year.
"It'll have to be a combined decision with the family. My mother will probably be helping me make that decision at the time," he said.
Non-wetsuit wearers were the next three top finishers in the Rangitoto marathon - Dan Able, 42, clocked 2:20:46, Logan Jacka, 36, came in at 2:23:26 and David Blackmore, 42, was fourth in 2:33:58.
Wetsuit merchants Tim Aitchison, 50, was fifth in 2:36:16 and Rachel Lilly, 26, was sixth and also first female (2:40:55).
