Well in our area the local patterns are well documented and attached to that place although they could be varied slightly. Perhaps it is a piece of folklore but it's what the fisherfolk themselves believed. The Humber Star was used by the keelmen on the Humber, and there are specific patterns for Filey and Flamborough. If it is just a myth it's a very logical one.

Nowadays of course the patterns are widely available so they will crop up all over the place. You can buy them online. Though you'd need a mortgage.