"He was a very experienced skipper ... he was someone who was out there and would give anything a try," the man said.
"But he wasn't stupid. He was a very safe boatie.
"Family was very important."
The man said initial reports of the 4 metre (14ft) boat were not accurate. The boat was actually 5.5m (18ft).
"As far as we are concerned he was an experienced boatie and wouldn't put five people in a small boat," he said.
Of the five onboard, only the 7-year-old was wearing a lifejacket.
Passing boaties Warren Coffey and Katikati College teacher Peter Besley came across the upturned hull about 5.30pm, after a day's fishing.
The pair then saw the four young people waving out for help from Matakana Island. After rescuing the four and calling coastguard, they brought them back to the mainland.
Yesterday, Mr Besley said: "When we spotted the group, they were all wearing lifejackets. The three older ones put theirs on after they were capsized."
Katikati College principal Neil Harray confirmed the 15-year-old boy was a student and the school was offering what support it could to the family.
Mr Harray said the incident was a "tragedy for the whole community".
"The thing about being in the community we are, everyone knows the community well. Everyone knows of the family and the kids and everyone's affected. It does impact the community," he said.
Tauranga bone carver and keen kayaker Nathan Pettigrew said while he did not know the family, he was keen to help with the search.
"Really, it's because someone's died and in this case it's actually someone's grandfather," he said.
Mr Pettigrew used his kayak to explore areas of shrubs and trees yesterday, where other water craft would have struggled to access.
He expressed frustration at the number of "senseless" tragedies on the water.
Mr Mair's son Nick Mair expressed the family's gratitude for the efforts of everyone involved in helping look for his father.
An air, land and sea search was initiated on Monday night with police, land search and rescue, coastguard, surf lifesaving club, fire service, Waihi mine rescue staff and volunteers taking part.
Yesterday, a two-day shoreline search began.
Waikato police search and rescue co-ordinator Constable Dave Pitchford said search efforts would be re-evaluated today.