Rescuers will battle tough conditions and a three-metre swell as they attempt to save a French sailor who has been stranded in the Southern Ocean for over two days.
Alain Delord set off a distress beacon on Friday after the mast on his 11-metre yacht broke in rough weather, 500 nautical miles off Tasmania's south-west coast.
The 63-year-old, who was attempting a solo around-the-world voyage, abandoned ship and took to the Southern Ocean in a life raft.
A passenger ship, the PV Orion, has made a 50-hour diversion to come to the Frenchman's aid and is expected to reach his position about 10:00pm (AEDT) tonight.
The Orion's captain Mike Taylor says tough conditions may make a rescue difficult, with 20 knot winds and a three-metre swell expected.
Mr Taylor says the plan is to launch a zodiac dinghy to rescue the sailor, but if the weather is too rough there is another option.
"The other alternative will be to come round him on the windward side and then kind of slowly drift down onto him," he said.
"And then it would be a case of getting a heaving line over to him, hook him up to our pulley and then just sort of drag him back to the ship."
The PV Orion was on its way back from an expedition to Antarctica when it received the distress call.
The Australian Maritime Safety Authority (AMSA) has dropped food and water to Mr Delord and maintained communication through an interpreter.
Mr Taylor says the Australian Rescue Coordination Centre will help locate the experienced sailor.
"Three days in a raft - he's probably not going to be walking," he said.
"[Although] he picked up the supplies they dropped him, so he's probably pretty agile and tough."
Mr Delord was following the route of the around-the-world yacht race the Vendee Globe.
AMSA spokeswoman Jo Meehan says Mr Delord is in reasonable spirits and has not reported any injuries.
"I don't want to underestimate the difficulty of the task for the PV Orion - his cruise vessel is not designed for search and rescue," she said.
"It will be difficult for him to put down his own life raft and collect the sailor.
"However, this process shouldn't take too long, and we expect to have the sailor on the Orion by nightfall."
Ms Meehan says the Orion was not legally bound to aid to Mr Delord.
"The master and the passengers and the crew of the Orion deserve a high commendation," she said.
"They've put the interests of this sailor and his safety of life ahead of their own commercial interests and it is a very commendable effort."