Cats can't go by plane? I think I saw one , but he was drugged to sleep or something.

The diesel fuel is very efficient. I took a cruise that went prob 1500 miles and powered all the lights and elevators onboard for a whole week.

There's probably space for extra fuel to get you across the ocean. I've even read that people take old sailboats and don't even use the sails. Since they are made for sailing, the hull shape is quite efficient. It prob just won't be super fast.