A US study of the prevailing wind and current conditions during the 13 months castaway Jose Salvador Alvarenga claimed to be at sea supports his remarkable tale of having drifted 8,000 miles across the Pacific.

Alvarenga made headlines when he washed up on far-flung Ebon Atoll in the remote Marshall Islands two weeks ago, 13 months after setting off from Mexico on a fishing trip.

Wearing only a pair of ragged underpants and sporting an unruly beard, Alvarenga claimed to have survived more than a year drifting across the Pacific by eating raw bird flesh, turtle blood and drinking rainwater and his own urine.

A University of Hawaii at Manoa study of ocean winds and currents in the Pacific during the time Alvarenga claimed to have been at sea supports his improbable tale.

The findings were drawn from a model originally developed to investigate variations in ocean surface circulation.

"Alvarenga's claim that he had been adrift for 13 months and that he came from Mexico falls well within the model's limits and is consistent with the prevailing pattern of wind and ocean currents during his ordeal," the study found.

Starting 200 nautical miles southwest of the Mexican fishing village, Chiapas, where Alvarenga began his odyssey in December 2012, the model's 16 tracers took a "remarkably narrow path" across the Pacific, passing by or nearing Ebon Atoll within 120 miles by January 31 2014, the study found.

The model's parameters were drawn from actual drift patterns of debris across the Pacific from Japan to Hawaii after that country's devastating 2011 tsunami.

"The experience with capsized fishing boats from the tsunami that reached the shores of Hawaii one-and-a-half to two-and-a-half years later guided us in using realistic model parameters to simulate the fisherman's boat drift from Mexico," said Jan Hafner, one of the study's authors from the university's International Pacific Research Center.

Alvarenga told officials in the Marshall Islands that he drifted some 12,500 kilometres (8,000 miles) across the Pacific after his boat's motor died on an overnight shark-fishing expedition in December 2012.

A companion, a 24-year-old man called Ezequiel, starved to death during the ordeal, unable to stomach the basic diet of raw fish, bird and turtle, and his body was dumped overboard, the survivor said.

Diplomats have said his story appears to stack up, with his account matching reports of his disappearance from Mexico, although his survival tale has been met with scepticism in some quarters.