From the kickstarter we knew that Ashes of Creation is going to have a Naval System, but until a few months ago we had no idea how intensive it was going to be. Oddly enough, they didn't bundle up this information into a presentation around showing off their plans for Naval Content, instead it came about due to a question on a live-stream.
What we know from hard and fast facts about the Naval system is that boats are destroyable, but we don't know how they get restored. We also know that ships cannot be summoned at sea which is going to make naval fights more meaningful. If you are engaged in naval combat and you get your ship destroyed, that is it. You are going to have to swim towards land in order to summon a new boat.
We also know players will have a Mariner skills tree. The more often they do different jobs on the ship (navigation, gunnery, repair) the more proficiency they earn in that skill and the better they get.
We know that ships will come in 3 sizes:
Small: Crew of 1-3 used for solo content
Medium: Crew of 8 (a party) used for group content
Large: Crew of 40 (a raid) used for raid content
We know there is going to be some sort of sailoring skilltree, that allows horizontal progression in terms of navigation, rigging, weaponry, ship repair, so the more time you spend doing these tasks on ship, the more proficient you will become at them. As of right now, this is the extend of information that we have.