"It's not a nice thing to happen on Christmas Eve," Mrs Stewart said.
The family was consoled by the thought he died doing what he loved but would have to wait until the middle of the week to get the results of a post-mortem examination and find out exactly how he had died.
"He was the most helpful person you could possibly have as a friend," Mrs Stewart said.
The family had planned to have a "relaxy" day yesterday.
"Nothing fantastic, we were going to have a lazy day. I'll tell you what though, I've already packed him a plate of Christmas dinner. I've put him aside a plate and wrapped it in paper.
"He doesn't know it but he does have it," she said.
The couple's sons, who range in age from 17 to 26, had put down their first hangi yesterday, something their dad would have been proud of.
"We're still talking like he's here. The boys are really sad and tearful but in the same sense they are happy he went the way he did," Mrs Stewart said.
His coffin would be put in his dinghy for the funeral.
"There won't be any seating, it'll be casual wear, bare feet, he'd have laughed at people if they were in their fancy clothes," she said. "And there will be a lot of grown men crying."
Mr Stewart's dinghy was found mid-afternoon and the Western Bay of Plenty harbour master began a search, eventually bringing the body to shore at 4pm.