Ellen MacArthur has slipped further behind record pace in her attempt to beat Francis Joyon's solo round-the-world mark of 72 days.
The Briton was 29 miles adrift of Joyon's track at 1600 GMT on Monday and is only likely to notch up between 100-150 miles in very light airs.
The Frenchman was fast at the same point off the coast of Brazil and covered 399 miles on day 58.
"Things could be a lot, lot worse," she said, trying to remain optimistic.
"If someone had told me I was going to be four days ahead at Cape Horn, I would have thought they were mad.
"But that time buffer has proven very useful in dealing with the complicated weather of the South Atlantic - if we had not had that advantage, things would be a lot worse now."
MacArthur, who has not been behind since day seven of her attempt (4/12/04), used the calm conditions to have one more look up the mast to check on her repairs, but admitted she was worried about the weather forecast.
"[I] Am thinking of what is the most precious thing I have onboard to give to Neptune as an offering, as clearly we need some more luck," she said.
MacArthur must cross the finish line at Ushant, off the French coast, no later than 0704GMT on 9 February to break Joyon's record of 72 days 22 hours 54 minutes and 22 seconds set last February.
Her shore team on Monday revealed that she will first put ashore in Falmouth, Cornwall, if her bid is successful.
MacArthur set sail from Falmouth on 28 November, and the decision took into account logistics, sponsors, the media and the general public.
French ports were also considered as MacArthur is a huge star in France, where solo offshore sailors are held in high esteem.
But the Falmouth option was also influenced by the Vendee Globe solo-round-the-world race in monohulls which is due to finish at a similar time in Les Sables d'Olonnes, France.
"The support we received in Falmouth prior to Ellen's departure was fantastic," said Mark Turner, chief executive of MacArthur's Offshore Challenge's management company.