Amateur rowers from the Langstone Cutters are competing in the London 2 Paris Rowing Race 2008, organised by British adventurer and Atlantic rower Jock Wishart.
The rowers have set their sights on conquering the Seine to raise more than £50,000 for the Langstone Lifesavers Fund, which supports several charities including the RNLI.
Speaking from the team's boat in London as they prepared to set off, rower Mike Gilbert said: 'It is a big event and everyone is itching to get on with it.
'We have worked hard; we have changed our diets, trained hard, taken time out from our families and we just want to get on and row.
'We usually raise money for local charities but because this was a bigger challenge we decided to go for a larger charity.
'So far we are almost halfway to our target with about £12,000.'
The mixed team of 10 set out from London to row virtually non-stop over seven days and 417 miles to Paris. They will be competing against a professional team along the way but, to give them an edge, will be singing their own sea shanty song, La Belle Paris, written by Alan Glock, official shanty singer for HMS Victory.
They started well, taking an early lead as the teams set off and were a quarter of a mile ahead as they reached the Thames Barrier on Friday. But organisers estimate that the race will not finish until this Friday – so there's everything to play for.
'We have always been rowing as a team,' added Mr Gilbert. 'We completed the Great River Race and were looking for a slightly bigger challenge. we looked at doing the Atlantic but decided it was too big – this is a week-long race and less life-threatening so we said "let's have a go".'
The Langstone Cutters, based in Chichester Harbour village, has 90 members, ranging in age from seven to 65.
The relay team is using a 34ft, six-oared, fixed-seat, traditional Thames Waterman Cutter rowing boat to complete the charity challenge.
Mr Gilbert said: 'I think the weather forecast is such that we are pretty relaxed. I think we can cross the channel safely with no winds.'