Groupe Bel have been forced to retire from the Barcelona World Race after Kito de Pavant and Sebastien Audiganes team completed a full assessment of their keel in Ushuaia on Wednesday.
The appendage itself and surrounding areas inside the hull have been reported as too damaged to allow any safe chance to repair them on site and resume racing.
The duo officially informed the race management at 17:36 UTC on Friday 11 March.
"Our round-the-world ends at the far end of the world," said de Pavant. "[It is] an unfortunate end after two months of racing, three oceans crossed and the rounding of three capes.
"Stopping the race is obviously as heartbreaking for us sailors, as it is for those who share their adventures everyday through what they have written and their pictures. The difficult decision was made with the support of Bek Group, which puts the safety of its men first."
The duo's resolution and motivation has held out to the end. They were in third position before their required 48-hour stopover in Wellington to repair their sails.
Groupe Bel then had to deal with a tropical low which they emerged from in good shape leaving Estrella Damm astern.
Just under 300 miles from Cape Horn, Groupe Bel was up to fifth place with serious ambition of giving her all in the Atlantic battle. Only on Monday afternoon, abnormal noises coming from the keel-head alerted the duo, who noticed that it was moving forward and backward in a worrying manner.
The two following days were particularly stressful as they tried to get to Ushuaia harbour as quickly as possible, since the keel threatened to come away from the hull at any moment. Rounding Cape Horn on Tuesday was nonetheless a poor but real consolation for the sailors, punctuating the effective crossing of three of the world's oceans.
Groupe Bel is the third IMOCA Open 60 to retire from the Barcelona World Race, after President and Foncia, which both sustained broken masts.
Event website - www.barcelonaworldrace.org