A man who drowned despite his friend's desperate attempts to keep him afloat for several hours was wearing a sub-standard ex-navy life jacket, which could not keep him up.
The desperate man managed to send two text messages to his partner after his boat sank, who dismissed them as a joke.
The death has prompted a coroner to warn boaties about the importance of good quality life jackets.
• Lifejacket scramble before sea tragedy
Anthony Murray Preston, known as Anton, had put on the inflatable life jacket after the boat he and four others were on sank in the Hauraki Gulf on August 16, 2011.
However, the jacket failed to support the 41-year-old properly and, after several hours of panic and struggle, he disappeared below the water and drowned.
Coroner Brandt Shortland said the life jackets on the boat, of a type now decommissioned by the navy, were not fit for use and "were never going to sustain life in a situation like this".
Mr Preston had been drinking before he and a group of four others decided to go fishing. They set off from Martins Bay near Warkworth on the 5.5m boat Mistress about 3pm.
Conditions were fine, but the boat got swamped and sank after the engine suddenly cut out about halfway to Moturekareka Island.
Mr Preston put on one of the three life jackets recovered from the sinking boat.
He tried to call 111 on his cell phone but could not get reception.
He then sent two text messages to his partner, asking for help, but she dismissed them as a prank, as he was a known jokester and she did not know he was on a boat.
A flare failed to attract a nearby boat and, as conditions turned choppy, the group decided to swim for Moturekareka Island.
Mr Preston, a poor swimmer, clung to his friend Sam Cash, who held onto a chilly bin with one arm and swam with another.
The two men made slow progress and soon lost sight of the others. After battling for more than three hours, both men were totally exhausted.
Mr Preston then started making gurgling noises and frothing at the mouth. He asked Mr Cash to take his will, and to tell his girlfriend he loved her.
Mr Cash encouraged his friend to "shout out to Jesus", which he did in desperation before going quiet. He then stopped breathing and went blank and lifeless.
After 20 minutes, Mr Cash decided to swim on without him.
Miraculously, all four others made it to Moturekareka Island after a six-hour ordeal. They sheltered there for the night and were rescued by helicopter the next day.
Mr Preston's body was later found and an autopsy showed he had over the legal driving limit of alcohol in his blood.
Coroner Shortland, who found Mr Preston died by drowning, stressed the importance of wearing a good quality lifejacket: "They may save your life."