The Rev John Challis, from the parish of Beeding, Bramber and St Botolphs, will be joined by Mark Hannington for the fundraiser in May.
Mr Challis said it was a big event to raise money for St Barnabas House hospice and the Raise the Roof appeal at St Peter’s Church, Upper Beeding.
While the pair prepare to pedal from Oxford to London, what they really need, he added, was someone to take on the publicity and fundraising side of things.
“We need someone with plenty of time and dedication to raise money for my church roof and the hospice,” he said.
“The hospice are on board (no pun) and are awaiting our Btmydonate website to go live so they can publicise the event but we need more help urgently.”
There was no-one suitable available within the parish family, he said, which is why Mr Challis is putting out the appeal.
He hopes an experienced charity fundraiser will be prepared to volunteer to join his small team.
He added: “I feel there must be someone out there who could help with writing letters and making contact with companies, etc.”
The craft they will be using was formerly available for hire on the Serpentine in London’s Hyde Park and the pair expect to be pedalling it along the Thames at two miles an hour.
Mr Challis said: “The pedalling has been done once before a couple of years ago, but only the once and the lads who did it raised money through the City of London.”
He wants to sell sponsorship on the boat and get further publicity through all the towns and villages they travel through and already has a company ready to make the signs to go on the boat.
The aim is to raise money for both the Worthing hospice and the £250,000 church roof appeal, which was launched last summer.
“Right now, Mark, my co-pedaller, and I are in training for the event, which is in May, and we are running out of time to raise the £5,000 that we want to make,” added Mr Challis.
Contact Mr Challis at The Rectory in Church Lane, Upper Beeding, call him on 01903 810265, or telephone the parish office on 01903 815850 with offers of help.