Kava's family have been told of the decision to suspend the search.
Paul Tuvae, who was on the boat, told the Herald yesterday that 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.
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. The fact that he can't swim, he wouldn't have been able to float long enough."
Friends who witnessed him fall weren't confident swimmers either, and it took time for the skipper to be alerted and turn the boat around, Tuvae said.
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.
Only one person was meant to be in that area for the barbecue.
"The ramp is locked and tied in place. I'm unsure as to how it was unlocked and untied."
Red Boats had cancelled all charters for the company's fleet until it was established what happened.
Somers said the company had owned the boat for 20 years and never had an issue with the ramp.
He was confident his staff followed the correct man-overboard procedure. They did regular drills and had done one that afternoon.
Red Boats provided life jackets but people were only told to wear them in an emergency situation, Somers said.
"We are devastated. We're working with the authorities to establish what has happened. The ramp's bolt is still in working order. I'm unsure why it was let down like that."
Kava's cousin, Ellie Sitaleki-Lovo, said yesterday Kava's father was so distraught
he couldn't bring himself to speak, he just stared out to sea.
"It's been really hard. It's a tragic loss. We're still hoping to find him.
"He always put other people first. He was always giving and he'd never ask for anything."
Elim Leadership College chief executive Darryl Booth said students and staff at the college where Kava had completed the one-year diploma in Christian ministries last year were saddened by the news.
He said Kava was a "lovely, really genuine guy" who would do anything for anyone.
"It's just incredibly sad. Some of the students are pretty upset with what has happened and not knowing what is going on.
"It's just really sad for the family not knowing so our whole organisation is praying for them."
WorkSafe NZ has been notified.
