Nick Hancock has been in touch with his supporters, saying there was nothing he could do but sit in his RockPod as large waves swept over the rock for hours.
Although he has not been able to get out and make a full damage assessment, he believes four barrels of rations lashed to the rock have been swept away.
He said: "It may be that I have lost barrels with more than two weeks of supplies. If that is the case, I may be unable to continue for 60 days as I had planned."
The Edinburgh-based chartered surveyor, who was on day 28 of his attempt to get into the record books, will make a final decision later about how to proceed.