Some people may have thought so into the 16th Century, but the idea that the Earth is round has been around for a lot longer. Claudius Ptolemaeus, better known as Ptolemy, was working with projecting the spherical surface of the Earth onto flat maps, and he lived 100 - 178 A.D.

As a strategy, Once you get a bit of language skills, one make out getting to a location that would be friendly to a stranded or lost seafarer. Pass yourself off as someone who was lost at sea, either overboard or through a sinking.