I don't mind waiting for them, but it's a pain to not know if they're coming at all.
I've sailed my sloop to Tanvu from Tawar Galan several times, and quite often I find the NPC ferry sitting half way between the two destinations, doing nothing. Maybe the captain is fishing, I don't know.
Anyway, I was thinking. Maybe the NPC ships should despawn after several minutes of being empty.
Then, at the dock, when you click the sign, or maybe a NPC, it will randomly spawn in 3 - 10 minutes and come sailing up to take you to your destination.
I realize its not very realistic, having ferries on demand, but I think it's better than standing there for long periods of time before concluding the ship just isn't coming today.
I don't mind the teleporter so much any more, they are a nice option for those who don't have time. But they cease being an option when the boats are all stuck at sea.