Daredevil rowers from Oxford were forced to abandon an endurance race across the Irish Sea in a Celtic longboat - because half the crew got violently seasick.

Oxford Rowing Club members Imogen Crawford-Mowday and Sian Findlay, 24, a graduate of Magdalen College, were attempting to row from Arklow, on the east coast of Ireland, to Aberystwyth in Wales.

But halfway through the 90-mile endurance test, Team Tenby were forced to quit after stormy weather made it impossible to continue.

Imogen, 30, who works at the Pitt Rivers Museum, said it was bitterly disappointing, but the team - one of 12 competing - still managed to raise £3,000 for the Paul Sartori Foundation, a hospice home care service.

She said: "We set off from the harbour and got off to an immediate lead, which we held for a couple of hours.

"It was sunny, but there were very long waves - it was very rough.

"After two hours, we came out into rolling waves, which made everybody feel terrible.

"An awful lot of people got very dehydrated and were seriously ill.

"The weather conditions were severe and it was becoming dangerous."

Seven of the 12 rowers and two of the three support crew were ill and eight hours into the journey, the skipper of the safety boat decided to pull the plug.

Crew transfers between the boats were becoming increasingly dangerous.

Imogen, from Iffley, said the event had already been postponed by one day because of bad weather and crews were surprised the race - which only six teams completed - was not completely abandoned.

Imogen, who did not suffer seasickness herself, said: "Everybody was clamouring to row because when we were rowing, we didn't feel ill - it was when people jumped on the support boat, they became ill.

"It was just getting dark, which was why the call was made.

"About five of us were prepared to carry on, but it was aggravating the seasickness for everybody else - even the medics were ill."

Despite the setback, Imogen said she was determined to tackle the next Celtic Challenge in 2010.

She said: "It was very disappointing - everybody was gutted. But I would definitely do it again."

Team Tenby captain Nick Tebbutt added: "We trained for six months for the event and it was a huge let down for us, our sponsors and supporters.

"But we still raised a substantial sum for a great charity."