It's a silly joke. I don't think it works in English, and I don't think it would survive trnaslation.
Leviathan - Wikipedia, the free encyclopedia was a sea-monster; it is sometimes used to refer to something very big. It is occasionally used as an adjective in this more general meaning. John Prescott is quite a bulky man. I've never heard a person's body referred to as a "hull", but the 'joke' is that the reader is supposed to think that 'One of them has a leviathan, instantly recognisable hull and has travelled all over the world' refers to the ship.