A self-employed handyman from Surrey is attempting to break his own record by rowing 620 miles, (1,000 kilometres) in less than six days - without actually going anywhere.
Mr Gower hopes to finish the feat on Monday
Nigel Gower, 38, from Pyrford, plans to row non-stop for 20 hours a day on an indoor rowing machine.
He is trying to beat his record of completing the distance in seven days, four hours and 44 minutes.
The record-breaking bid forms part of Mr Gower's training for an attempt to row across the Atlantic in 2004.
Money raised for charity
Mr Gower, who is also a rowing coach at the London Regatta Centre, in Docklands, will begin his challenge on Wednesday at the Brooklands Centre in Weybridge, Surrey.
He hopes to return to the Brooklands Centre for a further 20 hours on Thursday before moving onto London Bridge station on Friday.
On Saturday and Sunday he plans to carry out the feat at the Friary Centre in Guildford before finishing the challenge on Monday at Victoria Station in London.
A third of the money raised in sponsorship will go to Cancer Research UK.
For the 2004 challenge, Mr Gower with his rowing partner James Doust, will join 49 other two-man teams in the Row the Atlantic Challenge.