Huh. He was from Newfoundland. Had been a fisherman, came to MA to build houses.
There are a also islands on the East Coast of the US where people have been living so long by themselves that they develop their own strong local accents.
Unfortunately, when I google "Nantucket accent" or "Kent Island accent" all I seem to get are boutiques, decorators, bed and breakfasts.
Those accents are probably all dying out because of all the summer people.