EARLIER: A FRENCHMAN was in a critical condition in the Royal Hobart Hospital yesterday after suffering from a serious illness at sea.

A police search and rescue helicopter airlifted the welder from the L'Astrolabe, which sails to and from the Dumont d'Urville Antarctic research station, on Thursday.

The helicopter met the French ice-breaking research vessel  about 120 nautical miles south of Cockle Creek after 5pm.

The Australian Maritime Safety Authority reported the man's illness to police about 10am on Thursday, but at that time the vessel was too far south from Tasmania - more than 200 nautical miles - for the rescue helicopter to reach.

The vessel travelled north to meet the helicopter.

Senior Constable Josh Peach, of Tasmania Police Search and Rescue, said the pilot's first landing attempt was unsuccessful because of the rough conditions, which forced a doctor and paramedic to navigate a distance of about a metre from the helicopter to the helipad of the unsteady vessel.

``So we held there while the doctor and paramedic got on board and they were handed all their gear,'' he said.

``The ship altered its course to see if it would make a difference, and then the pilot made a second attempt and landed.''

Senior Constable Peach praised the ship's crew for their fast but dangerous work in securing the hovering helicopter to the helipad.

The helicopter returned to Hobart about 7pm on Thursday. The L'Astrolabe docked in Hobart at 9.30am yesterday, but Senior Constable Peach said the ill man could not have waited that long to be rescued.