THE SOLE survivor of a fishing boat tragedy has spoken of his ordeal for the first time.

Lachlan Armstrong, 27, from Lewis, was airlifted to safety after being found clinging to rocks on the island of Mingulay, south of Barra, by Stornoway Coastguard

He and and another crewmate had swam for shore after their crab boat, the Louisa, sank while at anchor in the early hours of Saturday morning.

However, only Mr Armstrong reached the rocks while his friend - who is said to have lost consciousness in the cold water and "drifted away" - remains missing despite a major search operation by police and the coastguard over the weekend.

The bodies of two other crewmen, Martin Johnstone and Christopher Morrison, have been recovered.

It is understood that the boat's life raft had failed to inflate properly and was filling with water when Mr Armstrong and his colleague, who has not yet been named, decided to try to swim to safety.

The two other crewmen stayed behind to hold on to the raft, but are believed to have succumbed to hypothermia and drowned. The life raft was empty when rescue workers found it.

Mr Armstrong, who recently became a father, said: "It's hard to explain exactly how I feel - the relief at being alive but at the same time the regrets and the sympathies I have for all the families involved.

"It'll never leave me, it's just so tragic. I can't put into words how devastating and upsetting it is.

"The water was so cold and the raft wasn't keeping us dry as it never inflated. That's why we weren't out of the water. You know the only way you can survive is to get out of the water and get away.

"I made the choice to try to go for land. I didn't know if I'd make it but I thought perhaps leaving the other two boys with the raft they'd have more of a chance to get on to it themselves."

The fisherman, who has survived without serious injury, added: "A lot went through my mind and when I did finally reach the rocks I was convinced the rest of them would be OK.

"To hear that they were all gone - it still hasn't sunk in."

The men are understood to have been asleep when the Stornoway-registered Louisa began sinking at 4am on Saturday.

Tributes have been paid to the tragic crewmen

Mr Johnstone, 29, was described as a "real grafter", who had joined the crew of the Louisa less than five weeks ago. A former paratrooper from Halkirk in Caithness had recently quit as a deck hand on the Kingfisher crab boat for a "change of scenery" after 10 years.

His former skipper on the Kingfisher, Neil Giles, 46, from Thurso in Caithness, said: "He loved his job and was one of the best crew you could ever get.

"I wouldn't have been surprised if he'd come back to the Kingfisher eventually and I would have welcomed him. He loved the water. Fishing was his life."

Another friend described Mr Johnstone as a "wonderful, kind-hearted man", while on Facebook a friend of all three men said they would be "sorely missed".

The Louisa is owned by brothers Duncan and Murdo Kennedy, of Lewis.

An investigation into the tragedy by the Marine Accident Investigation Branch is underway and is likely to focus on why the vessel sank at anchor and why the life raft failed to inflate properly.

Police Scotland will also conduct their own inquiry.