A Southland boat skipper shed tears as he recounted a Foveaux Strait fishing trip which turned to tragedy and ended in the death of his son and his best friend.

Barry Bethune told a coroner's inquest in Invercargill his catamaran Extreme One was well equipped and well maintained, but there was nothing he could do when a huge wave hit the vessel side-on during an evening fishing trip on January 3 this year.

The boat was flipped immediately and sank within 10 minutes, he said, taking with it his emergency VHF radio and emergency position indicator radio beacon.

All five people on board were wearing lifejackets. They climbed on to the hull but were unable to call for help because their cellphones were wet. When the boat sank they linked arms and began swimming towards White Island.


After several hours in the cold water, Mr Bethune's son Shaun David Bethune, 23, of Ryal Bush, and Lindsay James Cullen, 59, of Brydone, died and Mr Bethune and sisters Denise Zonneveld and Carol Saxton had to make the decision to let their bodies go.

They spotted the boat Easy Rider, moored off Ruapuke Island and swam to it. No one was on the boat, but their cries for help were heard about 10pm by boat-owner Rewai Karetai and his wife Gloria Davis, who were camping on the island.

Mr Karetai rowed out to them in a dinghy and towed them to shore.

Mr Karetai and seven others died in Foveaux Strait two months later when Easy Rider capsized and sank.

Mr Bethune said he was steering Extreme One in "sloppy" waves when the large wave hit.

"I didn't see it coming at all."

Ms Zonneveld, of Edendale, a friend of Mr Cullen's, said her sister was visiting from Wellington. Both were keen anglers and accepted an invitation to go fishing that evening.

The sisters were wearing several layers of clothing including thermals and leggings but the men were lightly dressed in jeans, T-shirts and sweat shirts.


Ms Saxton said she was in the cabin when she saw a wall of water "like light blue glass" come across the boat from the right.

The survivors said they knew Shaun Bethune and Mr Cullen were dead when they went blue and became non-responsive during the swim.

Mr Bethune cradled his son before letting him go, Ms Saxton said. Mr Cullen had been swimming between the two women and they made the decision together to release his body.

The bodies of both men were recovered next morning.

Maritime New Zealand accident investigator Ian Howden told the inquest it was well known that rogue waves could "come from nowhere" in Foveaux Strait.

Coroner David Crerar found Shaun Bethune and Mr Cullen died of hypothermia.