Mr Vaenuku tried to get back in the boat but the motor was still running and it got away from him.
The wind whipped the waves into his face and Mr Vaenuku started praying.
"I called out: 'Please God, help me. Take me back to my children, they came to Australia to spend time with me'," he told the Herald, voice cracking.
"I yelled out and yelled out. I just hoped that something would happen. I prayed and prayed and after about 20 minutes, a boat appeared. It came from nowhere."
Onboard were Justin Robertson and Errol Geange, whom Mr Vaenuku called his "Christmas angels". It took them three tries to haul an exhausted Mr Vaenuku into their boat. They returned him and his dinghy back to shore.
Mr Vaenuku said he wanted to publicly thank Mr Robertson and Mr Geange for saving his family's Christmas.
But Mr Robertson said he was pleased they'd been able to save him.
"We got there in the nick of time. His whole face was drained," Mr Robertson said.
"He was my best catch of the day, that's for sure."
Meanwhile, Mr Vaenuku's partner, Roi Ngatae, has banned him from stepping foot in his boat ever again.
The water safety sector has renewed calls for Kiwis to be smart this summer in a campaign for the first zero death toll over the Christmas holiday period.
Men make up 80 per cent of the annual drowning toll, and many deaths are due to boating accidents.
Five rules of the Boating Safety Code:
•Wear a lifejacket.
•Carry communications.
•The skipper is responsible.
•Check the weather.
•Do not drink alcohol.
•Patrolled beaches can be found on www.findabeach.co.nz.
•The NowCasting app is a great way to keep up-to-date with changes in weather as it provides automatic weather updates (wind and sea condition) for boaties via the Coastguard VHF network.