I would like to give credit for the invention of the stereotypical pirate accent to the actor Robert Newton, who played Long John Silver in the 1950 version of "Treasure Island", and then went on to star in "Blackbeard, the Pirate" in 1952 (among dozens of other performances). I wonder if we would have any pirate accent to affect if it wasn't for Newton, or if that way of speaking was ever heard before 1950?