So who's got the low-down on how this all works..?
I've seen that when I go to an island (the yellowy previously uncharted ones), I can go ashore and "sometimes" repair my ship. However, I've carted canvas and timber all around Corey's green Earth and can never quite seem to figure out when and how this ability appears. Is it really just totally random? Is it the 7th different island I visit that permits this to happen? Is it when I have a certain amount of the goods that the option pops up...?