"They weren't wearing lifejackets, they were just about demanding us to tow their boat back but we wouldn't because light was fading and I wanted to get out of there.
"We brought them on board with us. They had no VHF, they just seemed to think it was a joke. It is absolute stupidity."
Law requires a person to be 15 years old to operate any water craft capable of exceeding 10 knots.
Llewellyn said he has been a boatie all his life but he had never come across anything "as bad as this".
"We could've brought back a corpse, if one of those kids had fallen in they would've drowned. I don't think they grasped the dangerous situation, or the gravity of situation, they were in."
Llewellyn said the kids, who had gone out fishing and were about 15m off shore, had lifejackets on board but were not wearing them.
He said the weather was wet and cold with scattered rain and "good strong swirls of wind" and the kids had put themselves and their rescuers in danger.
"You cannot send an 11-year-old kid out to sea in a boat with three others younger. You wear your lifejackets all the time, not just when you want to, and you need to know your fuel."
Llewellyn said once the kids were on board they headed to the Kerikeri Cruising Club where their mother was waiting. By that time it was 6.30pm.
Police said they had been informed of the incident but did not have to attend.
