As I also posted over at Lightfighter, I know a Naval Architect in Gloucester, who has been advocating such a ship for a couple of decades, now. His design would be completely self-sufficient, to include recreation and school facilities for dependents.

For those interested, his name is Philip C. Bolger, and his design is largely sail powered, as mobility would be secondary to station-keeping. Of course, a nuke plant would keep it at sea indefinitely.

A very interesting idea; also was broached by Popular Science a couple of years ago.