Ocean rower Simon Chalk is in danger of being capsized by heavy seas and high winds.
Simon Chalk: Official protest
Mr Chalk, 30, is attempting to row the Indian Ocean from Australia to Reunion Island.
In the latest message on his website at BBC Devon Online, Mr Chalk said: "There's a
real danger of being rolled by these big, big seas.
"The major danger is that a wave might be big enough to crush the cabin or cause serious structural damage.
"One helpful aspect is that the boat feels an awful lot better
now that I'm 55 days into the trip.
"It's a lot lighter, so the righting movement is very positive.
"I am just trying to get through each hour - survive the storm
and keep on going."
Mountainous seas and ferocious winds peaking at 130mph have pounded his 23ft vessel for most of the two months since he began his bid to become only the second person to cover the 3,478 miles to Reunion.
By Thursday, he had travelled about 1,695 miles.
Property developer Mr Chalk, from Newton Abbot, Devon, has lodged an official protest against another attempt to become the fastest rower across the Indian Ocean.
Portsmouth rowers Rob Abernethy and Mike Noel-Smith have embarked on an attempt at the same record.
Mr Chalk is protesting because he says his journey will be nearly 40 miles longer.
He believes plans by the Portsmouth crew to be towed 37 miles offshore from their start in Carnarvan, Australia, prior to officially starting the row, invalidate their record attempt.
He said: "It has never been acceptable to take a long tow from starting port."
Mr Chalk said he took a tow of about one mile to clear a dangerous reef and then rowed through "incredibly testing conditions" before he was clear of the shoreline of Australia.