In all cases but one that I can recall, any ships owned or at the disposal of PCs (or groups/guilds) have been RP-only things and established through CDQ and or regular quest results. They were available for use in quest situations, but no one gets a private ship to take where they would like as a mechanical, in-game thing.
The one "exception" are the boat routes established to and from Stort on Alibor, which was still the result of CDQs and lots of effort on behalf of the Raven guild, but even so, the mechanical benefit to these routes are open and available to all, so the Raven guild does not have its own private network of ships for their use alone.