Bob Weise and Steve Shapiro, both 71, were rescued nine times in seven months as they sailed from Norway to Cornwall.
Mr Shapiro said fellow US citizen Mr Weise had quit the two-man crew for personal reasons but had left on "good terms".
He said he aims to find more crew and continue the pair's voyage across the Atlantic.
"I am looking for two more crew," said Mr Shapiro, a screenwriter and author from California.
The boat, named Nora, left Norway in July and is aiming for the US state of Maine.
Mr Shapiro said he may look to sell the wooden yacht and upgrade to a bigger boat.
"She is indestructible and seaworthy, but she is a little bit cramped," he said.
Veteran sailor Sir Robin Knox-Johnston previously criticised the American pair and urged them to "leave UK waters".
In their latest mishap they had to seek help in Hayle, Cornwall, when their sailing boat tipped over, causing a fire on board.
Mr Shapiro said Sir Robin's comments were "embarrassing" for him and Mr Weise.
"I am just doing the same thing he did," he said.
"I sincerely respect his reputation but even he had people helping him.
"I am just a guy with a passion for sailing."
One member of a two-man US yacht crew branded a "castastrophe waiting to happen" has quit the luckless vessel.