There has been some speculation over where the archetypal modern pirate accent came from. There is a solid theory that the accent is actually Bristolian in origin (The Guardian 2010).
Looking into it, many English pirates actually came from the West Country region. It is not that surprising knowing the history of this region, as especially Bristol was heavily involved in trading with the West Indies at the time. Famous pirates like Long John Silver and Robert Teach (aka Blackbeard) were supposedly born in Bristol, so when Disney set out to produce movies “Treasure Island” (1950) and “Blackbeard the Pirate” (1952) they appointed one and the same actor for both of the roles – Robert Newton (Trawick-Smith 2011). Newton was born in Dorset, England, which is very close to Bristol. So it’s safe to say he knew the West Country accent really well and he consequently used it in those two films.
Allegedly, this was how the pirate accent was born, as Newton continued to portray the two famous pirates in subsequent pirate movies.
It may be possible that if Disney had perhaps not cast Robert Newton, the pirate accent would have never become the way it’s perceived today. If it is, in fact, an accurate theory, it’s fascinating that just one actor could have such an influence on popular perceptions of a certain kind of character.
There is even an international Talk Like a Pirate Day, which is proclaimed September 19. If you would like to talk like a pirate, visit this site, or learn to speak it yourself:
References:
https://www.theguardian.com/theguardian/2010/mar/10/pirates-notes-and-queries (Accessed on 15.01.2017)
http://postlikeapirate.com (Accessed on 15.01.2017)
Trawick-Smith, B. 2011. The Origins of the Pirate Accent. (Accessed on 15.01.2017)
Proper Lush 