A maritime investigator believes an emergency locator beacon would have saved a man who died off the Wanganui coast in February this year.
An inquest is being held into the death of 19-year-old Geoffrey Hampton, who died after more than 12 hours in the water.
A report into the sinking of the boat Mr Hampton had been fishing from was made public on Tuesday at the inquest in Palmerston North.
Mr Hampton's father and a family friend they had been fishing with were rescued the morning after the runabout sank.
Maritime investigator David Billington told the coroner that if someone on the boat had activated a personal locator beacon, a rescue could have been launched earlier.
Mr Billington told the court the boat's three occupants did not have the right type of lifejackets for the area, but the owner had done the right thing by filing a trip report with the coastguard before leaving.
Mr Billington said the three men appeared to have made a considerable effort to swim to shore, and that may have led to them contracting hypothermia.
He said swimming would have encouraged them to accidentally swallow sea water, burn more energy, and increase water movement over their bodies and clothes.
However he said it was understandable that the men tried to swim to shore as they could see houses on the shoreline.
Earlier, survivors Alan Hampton and Duncan Powell gave an emotional thanks to the coastguard skipper who searched for them.
Mr Powell, who owned the boat, was tearful as he thanked Mike Carson and his crew for doing everything they could, even after they had been stood down, to find the men.
He said he hoped the experience had not altered their perception of volunteering for coastguard duty.
Mr Carson said he felt he could have offered more advice about searching for the men if he had known the police officer controlling the search was working alone.