KEY POINTS:
The grief-stricken father of two children who died in a boating tragedy has told how their mother battled to save them as the family launch sank quickly in the Hauraki Gulf.
Lindsay Rowles, 53, said his wife Tania rushed to their children - Erina, 8, and Travis, 5 - who were sleeping in the cabin when their 7.3m boat started taking on water early on Anzac Day.
Realising they were sinking, Mr Rowles and two family friends who were on the fishing trip lifted the anchor so they could motor to a rocky outcrop 200m away.
He said one police theory was that an anchor rope abandoned in the sea had wrapped around the propeller.
"As soon as I started the motor it could have wrapped around the prop and pulled us backwards.
"The worst thing was moving - we got as far as we could, you see - and I think the rope wound us down to the bottom."
The water came in in seconds and the sinking happened quickly, Mr Rowles said.
As the steel alloy launch went down stern first, the four adults were thrown from the vessel but the children were trapped.
Speaking exclusively to the Herald yesterday, Mr Rowles said his wife was struck on the head as she tried to get into the cabin as the launch sank.
"She was hanging on to the kids. It was just so fast," he said, his voice breaking with emotion.
"Tania smacked her head trying to get back in the cabin as it was going down. Lucky we didn't lose her as well."
Mr Rowles wondered whether the children's lifejackets prevented them from getting out of the cabin.
"We told them just stay where they were until we got close enough, which was too late," the grieving father said.
"Should have had them out with me. Should have been on the outside.
"I don't know how I'm ever going to get over it."
Erina and Travis were beautiful children, Mr Rowles said.
"They were into everything - kapa haka, all the sports they can play. Travis was ready to sign up to the North Shore rugby club. Erina loved her netball and swimming. Travis loved wrestling. Loved life."
The family had spent the day off Waiheke Island on a fishing trip with their two friends.
They had a swim off Palm Beach, and taught the children how to use the lifejackets. "They swam with their lifejackets on".
The group moored at Onetangi and had dinner at the RSA in Ostend, returning to the boat around 7pm.
They motored towards Tarahiki (Shag) Island and anchored 200m away to fish.
About 2am, Mrs Rowles was fishing from the back of the boat when she noticed water coming in.
She told her husband: "There's a bit of water at the back here."
He decided to motor to land and believes that whatever caught on to the boat caused them to sink rapidly.
He had time to make one mayday call, saying, "Help, we're going down".
The four adults dived among the flotsam trying to reach the children trapped in the wreckage, but the boat sank to 6m below the surface.
They knew they could not reach it, and clambered over oyster-covered rocks to wait five hours for daylight and rescue.
Mr Rowles said the four adults huddled together for warmth and were "wailing" for the lost youngsters.
"Horrible. Freezing to death," Mr Rowles said, trying to describe the night. "You can't imagine."
They attracted the attention of other vessels in the morning.
Mr Rowles, an electrical fitter in the marine industry - including five years spent fitting out ships at the Devonport naval base - said he hoped no one else ever had to experience such a tragedy.
He said he was familiar with the sea, and bought the launch after seeing it for sale on the side of the road.
The police had asked him not to reveal the previous owner's name, he said.
The boat was recovered from the seabed yesterday and will be examined today by investigators.
Yesterday, they would not comment on the cause of the sinking.
Mr Rowles paid $28,000 for the boat, a four-wheel-drive vehicle and a trailer.
"I'd just taken them for a holiday all around New Zealand in our new car and bought them a new boat. I wanted to treat them. They were worthy, intelligent children."
On Sunday, he took the launch out for its first run, and Travis joined him for a day's fishing off Rangitoto Island.
Travis, who had never been fishing before, caught three snapper and they had them for lunch.
"We were so happy to have that boat."
Mr Rowles said he had bought a spare battery, ropes, jumper leads and other safety equipment.
The launch had a working radio, radar and fish-finder, he said.
It did not appear to have any structural damage and Mr Rowles wondered if the bilge pump was the source of the water that came in.
"I want to find out why it happened. I don't want it to happen to anybody else."
He would follow closely the police investigation and was hoping for answers, "for my sake and my children's sake".
But for now he is preparing to bury his children, who were last night returned to the family home in Devonport.