Here, The Guardian's Notes and Queries section sets out to look at this pressing question.
One reader, Nader Fekri makes an interesting observation about where pirates came from and how they spoke:
For many people, myself included, the archetypal pirates' accent was that popularised by Robert Newton, who appeared in more than 50 films, most notably as Long John Silver in Treasure Island, a role he reprised on TV in the mid-1950s.
Newton was born in Shaftesbury, Dorset, and spoke with a distinctive West Country accent. Aboard most English/British ships, there were significant numbers of Scots (William "Captain" Kidd), Irish (Walter Kennedy), and Welsh (Admiral Sir Henry Morgan) sailors. It seems, however, that the largest group of sailors came from the south-west of England (Edward Teach, AKA "Blackbeard" was a native of Bristol and Francis Drake was from Tavistock in Devon) than anywhere else, which is unsurprising, given the pre-eminence of Bristol as the main trading port with the West Indies. So Newton's accent may well have been historically accurate.
All of this may seem silly, but it's got relevance to your study of Regional Variation on ENGA3, so read well me hearties and look out for the hidden treasure.
(Alternative titles to this post were:
Pieces of h-dropping
To err is human, to arrrrr is pirate
X marks the glottal stop)