[@Mercenary Lord] Sure thing, I'll move the CS over in a minute.

A lot of the basics will carry over from lake to ocean going craft, but I can think of a couple of sticking points. 

- The keel or centreboard wouldn't be as developed on a lake or river craft, because you're more worried about shallow draft than stability

- Related to the keel is the hull shape - river and lake craft are going to be rounder and flatter, with lower freeboard, to make getting on and off easier, while an ocean vessel will have a deeper v-shaped hull, for greater stability, it will also have less super structure above the water, so it isn't top heavy.

- Hull on an ocean boat will also be designed to cut through waves, which aren't as big of an issue in closed waters.

- Salt water; the inhabitants of the UI mightn't have any experience with salt water, as all of their water comes from rainfall. You need to destill or desalinate the water before you can drink it, rather than just filter or boil it.

I'll have a look around and see what I can dig up