THE family of a Papua New Guinea fisherman lost at sea for a month had almost certainly given him up for dead, consular officials said.

Benedict Jor was fishing alone for tuna between two islands when a wind shift swept his tiny runabout out to sea.

The 20-year-old sheltered under banana leaves and survived on coconuts and rain water he caught in a small container as he drifted helplessly in the St Andrew Strait north of New Britain island.

Mr Jor said he "prayed to God" and feared the worst after several boats passed without seeing him.

Miraculously he was spotted by a deck hand from ANL Wangaratta - a container ship carrying electrical goods from China to Melbourne - about 350 nautical miles off the coast.

He arrived in Sydney yesterday where he met PNG consular officials who are organising emergency travel documents to get him home.

"I can't believe I'm alive," he said.

"I thought I was going to be dead."

Having endured lashing rain, tropical sun and more than three weeks at sea Mr Jor's jubilation almost turned to despair when the wake of the passing ship tossed him into the water.

"I was fast asleep and then I saw this big boat coming to me and my boat was capsized," he said.

"I was screaming and holding on."

The rescue was no easy task having to turn the fully-laden container ship about-face and bring it to within 40m of his capsized boat before crew could throw him a life ring tied to a rope.

Consular officials have spent the past week in vain trying to contact the castaway's family but his tiny village, at the base of a volcano, near the island capital of Rabaul has no phone.

"They probably thought he was dead and declared him dead," PNG consular Pidiwin Tau-Vali said.

"There has been no information about a missing person from our office in Rabaul so his family has probably already held a memorial service for him."

A spokesman for ANL Wangaratta said he was "dead lucky" to be found floating in a shipping channel about midday on September 2.

"If the ship had passed at night there was no way he would have been seen," he said.

He was taken to the ship's hospital where he was treated for dehydration and hypothermia but has since made a full recovery.

Mr Jor is expected to board a flight to Port Moresby today.