A 4-year-old boy was left on Auckland's Queens Wharf watching his father hanging off a ferry after the gangway they were crossing broke and the boat started pulling away.

Carl Saunders says he was terrified that he would lose his grip and be sucked into the Fullers ferry's propellers and his son Kiel would lose his footing or jump in the water after him.

The 42-year-old yelled to strangers on the wharf to grab the boy as passengers helped him back on board. Maritime New Zealand may launch an investigation into the incident.

After visiting his father on Waiheke Island, Mr Saunders was on the 5.40pm boat back to the city on Tuesday night with Kiel, dog Elli and a family friend.


As passengers starting disembarking from the moored ferry, Kiel ran ahead on to the wharf but his father and friend were still on the gangway when the ferry started moving, and the plank ripped away from the wharf and was left hanging by its hinges.

The friend managed to grab the dog and pull himself up to safety on the boat but Mr Saunders had to be assisted by other passengers still aboard.

"I was screaming out for someone to grab my son," Mr Saunders told the Herald. "He only had to overstep and he'd be in the water as he's watching Dad pulling away, hanging off the back of a boat. Luckily two ladies took hold of him and kept him calm."

It's understood the throttle and gear selector had been in the ahead position causing the boat to surge forward. Mooring lines were also broken.

The master of the vessel has provided a formal report to Maritime NZ, a spokesman for the authority said. "At this stage, we're just getting some info together to see whether or not an investigation is warranted."

Fullers spokeswoman Del Morgan said the ferry was accidently put into forward motion which snapped the rope holding the boat to the terminal.

That caused the back of the ferry to move away from the wharf, damaging the gangway which had two passengers on it - they were immediately pulled back on to the boat for their own safety, Ms Morgan said.

Fullers is conducting an internal investigation into the incident.