Former Navy aircraft-carrier nuclear engineering officer here. The basic point --- that a carrier might be able to refine its own jet fuel --- is certainly valid. But so that future readers don't get the wrong idea: Any time a carrier is at sea, it does a lot of flight ops just about every day, whether for actual missions, for war games, or just refresher training. That in turn means most of the crew is hustling, usually 12 to 14 hours a day minimum, and sometimes 'round the clock. Maintenance has to be done in the gaps. When we were at sea, it was rare to get six hours of uninterrupted sleep in a night. Somehow I doubt that has changed.