Now he is on his way to the Auckland Islands for another repair mission.
The mission aims to repair and weatherproof a former base at Ranui Cove where Coastwatchers camped out in secret to watch for movement from Japanese air and naval carriers during World War 2.
Mr Clark (55) will make the 465km trip from the south of the South Island along with Department of Conservation staff, four other volunteers, and a team of more than 20 scientists and dignitaries.
When Doc rang Mr Clark in November of last year to ask for his help, he ''didn't know much about the base'', he said.
Since then, he's received a veritable deluge of information about the trip and the World War 2 history of the lookout.
He enjoys helping on Doc repair missions because it means ''other generations can go visit [the sites] over the next 40 or 50 years''.
He also likes getting access to places he might not otherwise be able to see.
Weather can often be extreme in the Auckland Islands, but it will not be anything new to Mr Clark, who did one volunteer repair job for Doc in Kahurangi National Park where he said the weather was ''even more extreme''.
''There were two-foot snow banks around our tent in Kahurangi,'' he said.
''I think [working in the Auckland Islands] will be all right.''
It's now been about a decade since Mr Clark's first Doc mission helping to repair his grandfather's hut in Fiordland, Clark Hut.
Clark Hut has held significance for the Dunedin builder over the years.
He has taken his daughters and nephews to visit it, and his father's ashes are buried there.
Mr Clark said that he is always proud to volunteer with Doc on repair missions, because ''when those huts aren't there, there's nowhere for people to go''.
