Roy Finlay waved goodbye to scores of supporters in Newfoundland on Friday evening as his female companion swung the oars into place.

He is attempting to beat the ocean rowing record of 55 days from Newfoundland to north-west Ireland, but his former crew members say he will be lucky to make it at all.

Finlay's last attempt to break a world rowing record backfired when his crew of 16 revolted, claiming that they had to do all of the work. They were also concerned about their safety on the 48ft vessel, Atlantic Endeavour.

His former shipmates fear that Colleen Cronin, the 29-year-old first mate and only member of crew on the 26ft Celtic Crossing, may not realise that she is to spend the next 1,800 nautical miles with a man nicknamed "Captain Calamity".

Almost a month behind schedule, Finlay, 38, of Renfrewshire, is adamant that the vessel is sufficiently "safe and strong" to withstand the threat of icebergs and storms.

Although the boat has a laptop computer, satellite equipment and radio, the pair are otherwise unsupported. They have only enough food and water for 60 days and leaving this late in the summer means that the vessel is more likely to encounter storms and extreme weather.

Before leaving St John's on the journey to Sligo, Finlay said there would be a progress report on the expedition website every day. However, the site was not working yesterday. The weather forecast for the route is fine this morning but, by evening, gale force winds of up to 45mph are expected.

Finlay's sponsor, Great Spirits, claims that only 10 people have successfully rowed from east to west and that the fear that the boat will capsize is always present. Finlay, however, was undeterred.

He described his rowing partner's experience as "virtually non-existent" but insisted that he chose his American companion for her "enthusiasm" and ability to learn. She has done little rowing but has completed five New York marathons.

"The challenge of rowing across the Atlantic is immense," said Finlay. "The constant threat of bad weather and difficulties of daily survival are compounded by the sheer physical stamina needed to keep the boat in motion day after day. I know with Colleen's help that I can do it."

Former crew members claim it will be less Cronin's help and more her ability to row around the clock that will be required. As the Celtic Crossing eased away from the shores of St John's, Newfoundland, she was already doing all the rowing.

Lynda Hennerbury, friend to Finlay and landlady at the local pub near St John's, said conditions were perfect as Cronin powered the boat away.

"They were nervy but prepared and about 200 of us waved goodbye as Colleen did all the rowing and Roy took the tiller," she said.

Former shipmates claim that in 1998, when they joined Finlay on Atlantic Endeavour to row from the Canary Islands to the Caribbean, the captain was so lazy and safety such a low priority that they jumped ship. The 16 crew members had each invested £5,000 in the blighted adventure.

Gary McCabe, of Edinburgh, is one of those who jumped ship in Cape Verde in November 1998. He is also one of five former crew now pursuing Finlay for compensation.

"My greatest fear now is that this girl's life is at risk," said McCabe. "I just can't believe that anyone would sponsor him. The only good thing is that he is heading back to Britain where it will be easier for our lawyers to contact him."

Kenneth Crutchlow, director of the Ocean Rowing Society, fears that Finlay has departed so late in the season that storms are inevitable.

"I want to wish them well and it is possible they may beat the record, but I have to admit they are leaving it a bit late", said Crutchlow.

Celtic Crossing is estimated to have cost £100,000 but Great Spirits refused to disclose how much it had invested in the project.

A spokesman said: "We are aware of Roy's background and his previous expeditions and we have made an informed decision to back this venture."

Celtic Crossing was designed by Finlay and American boat designer John Scarano. There are two sliding seats for the rowers and a 6ft sleeping cabin. Its safety features include an emergency position-indicating radio beacon, lifejackets and life rafts.