Dalin, who has been leading the race since 23 November, came through a violent storm in the southern Indian Ocean on Tuesday night but since Thursday has struggled with his speed, causing his lead to shrink and the rumours over the well-being of his boat Apivia to grow.
From sailing at 16 knots on Thursday he was struggling at six knots on Friday (1100 GMT).
Weather conditions remain extremely difficult for the leading boats.
Vendée Globe. Charlie Dalin : « Je mesure ma chance d’être là… » https://t.co/94SzqB3gos pic.twitter.com/wfzS2m8SV0
— Le Télégramme (@LeTelegramme) December 13, 2020
"There is an area of light wind to cross, my lead is melting like snow in the sun. Others are at 20 knots, due east, I am losing miles at high speed, I am fighting to get out of this area as quickly as possible," he said.
On Sunday, Dalin passed the second of the three mythic mileposts on the race route: Cape Leeuwin in south-western Australia.
It has taken him 34 days and 22 hours to get this far.
Unstable weather forecast for all boats
Fellow Frenchman Thomas Ruyant is in second place on board LinkedOut, with less than 124 kilometres separating the leading boats.
Yannick Bestaven is running third in Maitre Coq IV, just slightly behind Ruyant.
Dalin is expected to build on his lead over the next few hours, as he will be the first to profit from a strengthening south-west wind which will drive him towards Tasmania.
But the weather forecast remains unstable for all competitors.
The first three boats are the only vessels still in contention to be equipped with the water foils which enable the boats to fly in suitable conditions.
Damien Seguin and Jean Le Cam are leading the race for traditional hulls.
The ten leading boats of the 27 still in contention are separated by less than 700 km.
Meanwhile, while the solo non-stop round-the-world race lost its sixth boat with the retirement of Fabrice Amedeo (Newrest - Art & Fenetres) on Friday.
The 42-year-old skipper for was in 21st position, but was forced out after losing his second on-board computer which cut off his information feed on the weather. He has now ended his race in Cape Town.
