A father plans to row the equivalent of a marathon today to repay the charity which helped teach his daughter to communicate.

Matt Robinson wanted to find a way to raise cash for Down's syndrome Oxford, following the help and support the charity gave to him and his 22-month-old daughter Lucy.

The keen rower, from Middle Aston, decided he would take on the toughest endurance event in the rowing calendar.

Today, Mr Robinson, 36, and teammates Richard Maynard, Sarah Marshall and Alison Brighton, from Abingdon Rowing Club, will compete in the Boston Rowing Marathon in Lincolnshire.

The crew will row 50km — 25 times the average distance for a summer rowing event — in just over four hours. Mr Robinson said: "It is akin to running a marathon. It will be exhausting.

"I think we will hit the wall after about three hours, but we will just have to keep going and dig in so we can finish the whole course.

"There is no question we won't finish it, but we will be absolutely exhausted."

The crew have been training for six months for the event, held on the River Witham. After 13km, the rowers also have to carry their ten-metre long quad scull 100 metres around a lock, before returning to the water.

Mr Robinson said he hoped to raise as much as £4,000 through sponsorship, which is the equivalent of about a sixth of Down's Syndrome Oxford's annual budget.

Most of the money goes towards providing speech and language therapy classes for pre-school children like Lucy.

Katie Bain-Collins, from Kidlington, whose two-and-a-half-year-old daughter Millie learned sign language with Lucy at the fortnightly classes, said: "Their ability to communicate now is fantastic.

"Without the charity our family wouldn't be where it is today. We were very shocked when Millie was born and we didn't know how to cope.

"We went to the charity and they were there for us then and they have been with us ever since."

Down's Syndrome Oxford also provides help and advice to another 150 families whose lives have been affected by the condition.

To find out more about the event, or to make a donation, visit the website at smartgive.com/funds/dsobostonrow2008