These ships float over the cities and seashores scouting for anything that can be turned into fuel. They may not look like much, but you'll be glad to have one when you run into trouble - or need gas.
Ian McQue is a concept artist in Edinburgh who has created a series of images featuring floating ships that look like fantastical versions of boats on Earth. I love how battered and lived-in they look. They also remind me of Karl Schroeder's Virga series, where people fly through blobs of atmosphere in floating in space, piloting ships that I imagined looking very much like these. You can see more of his work on his website.
(Thanks, Richard Green!)
The top image is called Pilot Boats.
The Last Airborne