The sunken boat was found and recovered yesterday and marine experts were examining it today to find out what went wrong. It was believed the motor stopped near Kawau Island and the boat filled with water and sank within seconds.
Senior Sergeant Martin Paget, from the Auckland police maritime unit, said today the boat had a marine radio fitted but there was no time for it to be used.
"It sank too quickly. It took on water and sank so quickly they didn't have a chance.
"That is a common theme which we are trying to get across to boaties. It is nice to have all this fitted equipment but to be honest most fitted radios in a small boat are more suitable to talk to your mates about where the fish are."
He said radios did not work when a boat sank and they got wet.
"People need to be prepared for that eventuality and have something that will work after it had got wet."
He said boaties should consider an emergency beacon, flares in a floating box they could grab if the boat was sinking and a waterproof, hand-held VHF radio.
The boat also had flares but Mr Paget said it was not yet known why they were not used.
Mr Paget said it was a tragic lesson on the wisdom of wearing lifejackets and not just meeting marine requirements and having enough in the boat for every person on board.
Mr Preston was separated from the others who swam to an island near Kawau Island, where they spent a chilly night before being rescued the following morning and flown to hospital.
- NZPA