An Australian sailor who survived two months in the Pacific Ocean by eating raw fish and drinking rainwater is "stable and very well", a doctor says.

Sydney resident Tim Shaddock, 51, and his dog Bella left Mexico for French Polynesia in April, but their boat was damaged by a storm several weeks later.

They were rescued by a trawler this week after a helicopter spotted them.

The doctor aboard the tuna trawler told Australia's 9News that the man had "normal vital signs".

Mr Shaddock embarked on his more than 6,000km-long (3,728-mile) voyage from Mexico's city of La Paz - but soon became stranded after his vessel's electronics were cut off by bad weather.

It left the sailor and his dog drifting in the vast and hostile North Pacific ocean.

When they were finally found off Mexico's coast two months later, he was far leaner and sporting an overgrown beard.

"I have been through a very difficult ordeal at sea," he told 9News.

"I'm just needing rest and good food because I have been alone at sea a long time. Otherwise I'm in very good health."

Mr Shaddock said fishing gear had helped him to survive.

He also managed to avoid sunburn by sheltering under his boat's canopy.

Soon after his rescue he was seen smiling and wearing a blood pressure monitor on his arm.

He is also able to eat small meals.

The tuna trawler is now heading back to Mexico where Mr Shaddock will undergo medical tests and receive more treatment if needed.