The challenge is typically the infrastructure. In short-sea shipping you go to a lot of different local ports. Sometimes you pull in; you can't even get to the edge. You have to take a rowboat to shore to tie up your lines. It's a little trickier to get LNG available in all the places you would need it to make the complex kind of routes we make on the Great Lakes.
It works great with a ferry, back and forth, point to point.