Logistically speaking, they probably didn't talk in the way displayed in POPULAR culture. Phrases like "ARRR!" are completely redundant. 17-18th century literature and documents show no parallel in speech between it and movies/tv shows such as Spongebob and the Pirates of the Carribean. In all likelihood, they spoke like regular poor, lightly educated aspiring seamen, ex-soldiers, and fishermen. It was usually these groups of people who decided to partake in the life of a pirate.