Hey this might be something I am missing (and perhaps a fault of the UI) but no matter what I do Cogs never become Caravels in my playthroughs. Am I missing a dependency or a special building to enable them? Thanks, I wanna settle the new world!

There seems to be two types of boat research. The first is where you research an actual boat that will pop out at a harbor if you build it. The second is a free upgrade to your military units that allows them to turn into that type of boat whenever they get into the water. They will take on the unit strength and ability to travel in water that the "boat" has. I just posted extensively asking about this in the Open Dev forum. 

Long story short, once you've researched caravels, all your military units will have caravel characteristics in the water. This benefit will cost you nothing, and they don't need to return to your territory to do it. I currently have a Harrapan runner (Ancient era unit) and two crossbows (Medieval era) floating around as a 3-masted Fluyt boats (Dutch caravel replacement unit).

This makes more sense but only I took Korea and there is a specialist artillery boat and I still couldn't build that one. Seems like it should be a military unit over a transport