Vikings had been building and sailing for hundreds of years in equipment they had developed and built. Rather different to those that survived the bombs and I doubt any of them know much on sailing modern ships. Ships in FO3 look more destoryed than slightly worn, even the aircraft carrier has broken in 2. Trains year they are working, however the NCR seem to have set up industry and are making the tracks. We've only seen 1 working car in the Fallout games that I can remember and the player has to make it for fast travel.
I do think an interesting idea would be what happened to the warships and submarines that were out of port?
Sort of my point, so we don't know what state Europe would be in, but still if they could manage to mount an expedition to the US it would seem to be in a better state than the East coast at least. Although would expect Europe to have more rads due to the close proximity of so many big cities.