Tuvae said the family was relieved "in a way" as it gave them closure.
"It's unreal he's not here any more."
Kava, from Mangere, died when he fell through the back of a party boat. It was his friend Carl Tuvae's 30th.
Paul Tuvae, who was at the party, said Kava went to the back of the boat to check on men cooking on a barbecue. As they were talking, he leaned against a barrier. It released and Kava fell backwards into the freezing, pitch-black water, Tuvae said.
The barrier, when unlocked, acts as a ramp to get on and off the boat.
"It was a bit rough and the boat was moving pretty fast," Tuvae told the Herald.
"The fact that he can't swim, he wouldn't have been able to float long enough."
Red Boats owner Andrew Somers said the ramp wasn't broken and staff had since tested it.
Kava was in an area at the rear of the vessel which was off limits to patrons, Somers said.
Hazel Jones from the House of Hope, a faith-based Manurewa drop-in centre that Kava frequented, said they are grieving for the loss of such a "humble, giving and encouraging person". Jones said he would come in and serve at the shop after working a full night shift. He would buy young people ice creams and coffees for adults.
"He had a heart for the homeless and would often buy them food and take them for haircuts. He was a man who did not talk about his good deeds, but for those of us who knew him, he set an amazing example of good works and looking after the needy in the community.
"Tevita has left a legacy for all of us."