Joe Westland, 63, was skipper on the supply vessel St Patrick when it was attacked by a gang of masked gunmen in the Gulf of Guinea.
Travelling in two speedboats, armed with assault rifles and sledgehammers, the pirates ransacked the boat and took the skipper hostage.
Their plan was to extort Mr Westland's company, PW Nigeria, in exchange for his life. And if his employers failed to come up with the money, the pirates threatened to set him fire.
"It was terrifying," he said. "While we were heading towards land, one of the younger members poked a gun in my face.
"He said he hoped that my company had plenty of money as they were going to demand 200m naira (£750,000) and if the money was not paid, they were going to burn me alive."
Mr Westland was then taken to the coast where he was left, without food, in a mosquito-ridden shack.
Having being bitten several times, Mr Westland contracted malaria and his health began to deteriorate, so his captors negotiated a reduced ransom of £50,000.
He added: "I was scared and increasingly unwell. I just lay there and tried to conserve my strength.
"They were concerned I was going to die in their hands, and agreed to accept this money.
"Several hours later I was taken by gunman out to sea. I still thought I was going to be killed at the handover."
After the exchange, Mr Westland was taken west to Lagos where he was met by officials of the British high commission. He then flew home to his family in Angus.
Although awaiting a settlement from his company, the skipper remains traumatised by his ordeal which happened in May and is in need of psychiatric care.