AUSTRALIAN rescuers were last night "hopeful" that British yachtsman Tony Bullimore was still alive after spotting a new distress signal from his capsized boat in the Indian Ocean.

As hopes began to fade for the former Royal Marine, rescuers noticed that an alarm beacon had been activated on the yacht, which is upturned in a virtually inaccessible expanse of ocean, 1,500 miles south-west of Perth.

Mike Calway, senior search and rescue coordinator at the Maritime Rescue Centre, Canberra, said: "We have noticed a different mode of transmission from his beacon, which must have been manually done.

"That would indicate that he must be around to have changed the switch from normal to alarm mode. We hope he is safe inside the overturned hull of his boat or in an overturned raft nearby."

Bullimore (57), who was competing in the Vendee Globe single-handed, round-the-world race, ran into difficulty when his boat Exide Challenger hit severe gales on Sunday. It capsized in such a remote spot that earlier search planes were unable to investigate the surrounding waters thoroughly.

Calway said the rescue organisation had never attempted a rescue operation so far from land before, adding: "One of our aircraft will be taking off very shortly to proceed to his position, but it will take about seven hours to reach him.

"We are hopeful. It's just a question of whether help can arrive in time and if he can survive the cold temperatures out there."

Fellow troubled competitor Frenchman Thierry Dubois was spotted earlier clinging to his up-turned vessel and was thrown a lifecraft by rescuers. Dubois (29) clambered into the raft - dropped by an Australian airforce search plane - at 11 am yesterday, and now awaits the frigate HMAS Adelaide to take him back to Perth.