Nothing has been heard from 43-year-old Roufs since midnight GMT last Tuesday. No contact has been possible by radio, the satellite position beacon has sent no signal and there has been no emergency distress beacon.
Fellow competitor Isabelle Autissier abandoned an effort to search for him when she was exhausted by the conditions, including near 80mph winds, and was further hampered by a damaged mainsail halyard.
A further three competitors, Marc Thiercellin, Bertrand de Broc and Herve Laurent, had been diverted but were not due to be in the zone until late last night and a Panamanian-registered cargo ship, the Mass Enterprise, was also searching. But no one knows where to look. The search zone is about two-thirds the size of Belgium and is too remote for an air search.
The organiser Philippe Jeantot, whose race is virtually in tatters as the leader Christophe Augin is the only one of the original 16 who has so far completed the course normally, has asked if satellite photographs can be taken to help with the search.