Technology is not at this moment a planned feature, given the absolute stagnation of Westeros even a millenium after the Doom. Merc navies aren't possible because letting the North have access to so much as one single boat breaks the AI, not to mention makes it way too easy for everyone to ignore the restrictions of geography. Trust me, you don't want this. As for Driftmark, I'll talk to the others, but for now the boats you want are on Dragonstone (which you are connected to).
It isn't islanders. This is just Driftmark.
This isn't the case at all. You have ships. They're on Dragonstone. Go take them.
Thanks for the info. Now I just have to declare war to my liege Stannis to conquer Dragonstone. Sad, we are the bestest friends...
Sorry, I must have generalized the Driftmark situation too much. Obviously I have experience only about this campaign (my first and only at the moment).
Whether the other vassal islands of Dragonstone, for example the Celtigars have ships or not, I feel they should have. I got the feeling (from A Clash of Kings) that their might has both traditionally and at the time of Stannis's campaign relied mainly in the navy, because the islands were too small and rocky to feed large populations and therefore unable to raise hardly any armies. The bulk of Stannis's land army came from the Stormlands (and of course the Reach after certain events), not from the Narrow Sea lords who traditionally commanded their own ships and marines, roughly the same way as the Ironborn (although the ships, troops and tactics were different). Therefore I feel that making ships available, somehow, to Narrow Sea lords (beyond Stannis) would be logical and faithful to the book series.
But in the end, I believe you have good reason to make ships unavailable to avoid problems with Northerner AI. I must just forget playing the Narrow Sea lords (my favourite area) and roleplaying them (as I said, you can always try to play marry-assassinate-inherit game to get started).
By the way, how do you use spoiler tags? I would like to put the longest paragraph behind spoiler tags, just in case.