The skipper of a New Zealand fishing trawler which rescued survivors of the capsized Oyang 70 in the Southern Ocean says he is not surprised the 82 metre Korean vessel sank in the way she did.

"The fact that the captain went down with the ship shows to me that he knew what he had done was wrong," Greg Lyall of Christchurch told a Coroner's Court hearing in Wellington today.

His impression was that the cause of the sinking could be attributed to the size of the catch being hauled at the time, he said.

A large net holding an estimated 120-130 tonnes was said to have been pulled aboard the Oyang 70 in the early hours of August 18, 2010, causing the vessel to lean and take on water, the inquest heard earlier this week.

Korean captain Hyonki Shin was loathe to dump the catch in time to save his ship. As panicking crew members ran to release inflatable life rafts or dived overboard into the freezing sea, Mr Shin refused a life jacket and, clinging to a pole on the bridge, went down with the 38-year-old vessel.

His body, along with those of two Indonesian sailors, was not recovered. However, those of three other Indonesian crewmen were.

Mr Lyall said if the Oyang's processing factory was full from the previous bag and a large net full of fish was hauled onto the main deck, it would have affected the vessel's stability.

Southern blue whiting - thought to have been the bulk of the haul - was "a very fluid fish" which would slump easily and, if uncontained, would move freely from side to side.

He said if the boat was "light ship" and had sailed with less than a full load of fuel, combined with the fact there were fish in the pounds and a huge catch on deck, it could have caused the vessel to roll heavily.

That, in turn, would allow more water to enter the factory deck, increasing the list and resulting in the ship going over and sinking.

He had been told that fish was being processed in the factory and there were more fish in the ponds, Mr Lyall said.

On his ship, the Amaltal Atlantis, the practise was not to fish while processing.

"We fish for quality, not quantity."

He described the dramatic hours which followed the sinking in the early hours of August 18, 2010, in calm seas near the Bounty Islands, 740km east of Otago.

The South Island-based Amaltal Atlantis was three days into a 45-day fishing trip to the area and was the first of several fishing trawlers which rushed to the scene of the capsized Oyang 70 in after a mayday call. The crew found themselves in a "large debris field" in poor visibility, the inquest heard today.

Mr Lyall said a strong smell of diesel alerted the New Zealand rescuers to the scene in the thick fog. Life rafts, ropes, cod ends, nets and deck boards from the sunken ship cluttered the area.

"This complicated the rescue efforts as the ropes kept fouling the propeller of our rescue boat," he said.

The three crew members had to raise the motor of the Zodiac inflatable 10 or 12 times to cut debris away.

A Russian vessel in the immediate area also deployed a rescue craft but was unable to assist as its props were fouled quickly by floating rope.

The sole rescue boat managed to recover three life rafts from the sunken ship before a fourth was seen containing three people partly submerged in water and oil. Two of them seemed to be suffering from bad hypothermia, and after being winched aboard Atlantis they were warmed up and put to bed.

Mr Lyall said it was difficult communicating with skippers of other fishing vessels which arrived at the scene. Language difficulties made it hard to coordinate the rescue attempt.

Three bodies retrieved from the water were those of Indonesian sailors Samsuri, 39, Taefur, 35, [SUBS TICK] and Heru Yuniartu, 25.

Those of two other Indonesians and the Oyang 70's Korean skipper have not been found.

Through the long hours of the rescue, the New Zealanders picked up the four remaining life rafts from the Oyang.

That, said Mr Lyall, was so other ships searching would not think there were survivors on the rafts.

"We also recovered two long lengths of mooring lines so vessels would not get entangled."

In all, 45 crew members survived.

The Amaltal Atlantis crew and company have been lauded for their part in the rescue.

Coroner Richard McElrea expressed his thanks before he adjourned the inquest this afternoon.

- APNZ