"I think you have too many substantial problems to head into harm's way," Mr Shaughnessy told Dr Paris, who posted Farr's concerns on his blog site.
"The boom-end failure is a substantial one. The jury-rigged mainsheet arrangement looks very prone to chafe.
"That, combined with the jury-rigged reefing arrangement, leads me to believe that a substantial failure is possible.
"To have this combination of problems in your injured state is inviting disaster. Please make the prudent decision and stop," Mr Shaughnessy said.
Dr Paris said yesterday he had decided to take the advice and was now headed for Cape Town, some 2700km away.
"To continue in the face of the sage advice would be foolish in the extreme, and cruel to my wife, family and friends.
"I must now abandon this dream."
Dr Paris said his physical condition improved daily and was not part of the decision.
There would be no second attempt, he said.
He said the boat would be shipped from Cape Town to Maine, restored with the lessons learned, and be the fast family cruiser for which she was intended.
After more than a month at sea, Dr Paris said he was "neck and neck" with the late Dodge Morgan who set the record of 150 days in 1986, at age 54, on his cruise yacht American Promise.