SYDNEY -- Rescue authorities said Friday they may lose track of French yachtswoman Isabelle Autissier, adrift in huge Antarctic seas, because her two emergency radio beacons will run out of power before she can be rescued Sunday.


Radio stations have been asked to broadcast a message to Autissier to turn off one of the beacons before they both run out of power, said Keith Hopper, of Australia's Maritime Safety Authority.


"We really fear we may lose her if both beacons run out of power," Hopper told Reuters. Each beacon has 48 hours of power.


Radio France, Australian state-owned broadcasters and some commercial stations in Australia have agreed to air the message in French and English.


Autissier, 38, had been heading for Sydney in the second leg of the BOC Round the World Solo Challenge when she activated the emergency beacons Wednesday afternoon.


Autissier's normal radio communications have been severely damaged. A survival kit, including a raft and radio, was dropped to her from an Australian air force Hercules plane Thursday, but Autissier has not made radio contact.


"We just don't know why she hasn't used the radio," Hopper said, adding Autissier may have decided to try to get some sleep after battling the wild seas for 24 hours.


The Hercules found Autissier's dismasted yacht, the Ecureuil Poitou Charentes 2, being pitched wildly in 50-knot winds and gigantic seas about 900 nautical miles south of Tasmania.


In a brief garbled radio message to the Hercules, Autissier said there was "something else wrong" besides the broken mast, according to one of her shore crew who was aboard the plane. Serge Viviand said whatever else is wrong with her boat must be serious or else she would have erected a jury rig with the portion of the main mast still on deck.


"She would not have used the distress call unless she had lost control down there," Viviand told Reuters on Friday. "I think it must be her steering. She may have lost her rudder."


Autissier was forced to erect a jury rig when she was dismasted early in the Cape Town-to-Sydney leg of the race. That time she managed to make her way to the French Kerguelen Islands in the southern Indian Ocean and installed a makeshift mast.