Why do pirates say “Aaaaaar”?

BlackbeardI was performing my new pirate-themed birthday show over the weekend for a multi-national crowd, and twice I heard people speaking to their children in different languages, both of them obviously talking about pirates.

How did I know?

Because both parents at some point said, “Aaaaarrr”, in that gravely pirate voice that appears to be universal.

Now, “shiver me timbers”, another great pirate saying, makes sense to me. A pirate has a ship, a ship is made of wood or “timber”. A storm, a battle, attack by a giant squid… all these things would make the timbers shiver.

But why “Aaaaaar?” No idea.

On a related note, do you know where pirates get their coffee?