A high-seas raid on a yacht in storm-force winds ended in one of the largest cocaine hauls and the jailing of three Englishmen yesterday.

The 65ft sloop Dances with Waves has been tracked for weeks from a high-tech anti-drug smuggling base in Lisbon. It was in danger of sinking when the decision was taken to make the arrest 170 miles off the southwest coast of Ireland last November.

The sailors, from Devon, gave themselves up when the Irish naval officers caught up with them and their cargo of more than 1.5 tonnes of high-quality cocaine. With purity levels above 70 per cent, the drug could have fetched up to £500 million once it had been adulterated for the street market.

Philip Doo, 52, from Brixham; his former brother-in-law, Christopher Wiggins, 42, of Mirador de Costalita, Estepona, Málaga; and David Mufford, 44, of Torquay, were each sentenced to ten years after admitting being on board an unregistered ship and possessing cocaine worth more than €13,000 (£11,600) for sale or supply. The case is one of the biggest successes in recent years for the Serious Organised Crime Agency.

Friends of Doo said yesterday that he may have been under pressure to bring the drugs across the Atlantic. Within days of capture he wrote to the commodore of his local yacht club to apologise, they said.

A former shipwright and the father of six children, Doo was said to have fallen into financial difficulty after taking up property development. Chris Bedford, the chairman of Brixham Town Council, said that Doo would never have agreed voluntarily to make the journey during the hurricane season with an inexperienced crew.

Mufford was seasick for most of the transatlantic voyage, losing 2st (13kg) in weight. Wiggins was said to have been so hard up that among his possessions police found a docket from a pawn shop for his grandfather’s watch.

Mr Bedford, a yacht club member, said: “He wrote almost straightaway from Cork jail and said, ‘I am frightfully sorry, I might have brought the yacht club into disrepute’.

“He even expressed a fear he could never come home again, that people just wouldn’t accept him, and I had to convince him that wasn’t the case.” Mr Bedford said that Doo was “not a seasoned drug-dealer thug. This is an expert seaman who got conned into something of a far larger scale than he ever appreciated and it was too late to get out of it. My impression is that he wasn’t a willing participant. I have a suspicion that he felt his family were under some threat.

“But he can hardly say he didn’t notice a couple of tonnes of cocaine stuffed in the bottom of the boat. He was caught red-handed. He accepts that with enormous, genuine regret.

“He was at the bottom of a big food chain and as usual the little guys are in the dock and the big boys are walking away.”

The cocaine haul, packed into 75 bales hidden inside the hull, was the largest quantity discovered in recent years on a boat attempting directly to import the drug into Britain.

Cork Circuit Criminal Court was told that none of the men had criminal records. They were recruited by a gang that offered each of them a sixfigure sum to bring the Colombian cocaine across the Atlantic.

The men first travelled to Trinidad and Tobago, via Spain and Venezuela, where Doo bought Dances with Waves with a false Irish passport. Four months later he brought the yacht to Europe.

A study of its global positioning satellite system revealed that it was programmed to track the southern coast of Ireland before arriving in Caernarfon Bay, North Wales.

Judge Patrick Moran said that he could only shudder at the thought of what havoc the drugs could have caused to young people and their families.

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