You don't go huntin' Pirates with little boats and little guns, you send in a squadron of these.

http://www.youtube.com/watch?v=Zf2ka9RsFQ4&feature=related

A 30mm gatling gun that fires 6,000 rounds per minute. Death from above. Air superiority is the quickest way to eliminate the Pirate Problem. Just ask any of those Republican Guards on the "Highway of Death".