Saunders said Eagle used infra-red equipment to spot the person in the water. The 3m aluminium dinghy, equipped with rods and fishing gear, had drifted some distance from the buoy.
An ambulance spokesman said the trio were suffering from severe hypothermia and were taken to hospital for treatment.
The trio, who are workmates at a scrap-metal merchant on the North Shore, suffered severe hypothermia but were released from hospital.
Last night, Mau said: "I am very lucky to be alive. The boat tipped. I spent 2 hours in the freezing water. The only reason I survived was because I was wearing a lifejacket."
Sergeant John Saunders of the police maritime unit paid tribute to the quick-thinking of the captain of MV Ninghai. "When the ship was going past A Buoy, the crew could hear people yelling for help," he said.
"When they looked at the buoy they found two people clinging to it and rescued them," Saunders said. "They are incredibly lucky."
Saunders said the family were on the verge of reporting the trio overdue from their fishing trip when they were contacted by police to say they were safe.
The upturned boat was towed in by the Auckland Coastguard.
Police were unsure how the boat capsized, but the men would be interviewed once they had recovered.