If you are interested in the origin of pirate lingo and elocution, Gretchen McCulloch has a good explanation in Slate today in honor of Talk Like a Pirate Day. Look it up at Why Do Pirates Talk Like That?
But here’s a clue and it is both surprising and logical:
So don’t bother reading through all those tales of larceny on the high seas: the traditional pirate which we once dressed up like for Halloween never said “Argggh.”
And now for something educational …
Never forget: it’s all fiction.