I have a mental picture of a mercury delay being rocked back and forth by the motion of a battleship :-) Certainly mechanical analogue computers were common in fire control, and must have got replaced by something more modern, but I would restrict the list to stored program machines. Nickel delay lines were likely used and drums used directly for executing code would of course work on a ship too. Williams tubes maybe, and the earliest core memory machine would have been military too. Maybe because they are excluded by secrecy, as happened with the UK's WW2 German code breaking machines until the story got out and Bletchley Park was saved. In my first job I came across several military computers, but they were for use in aircraft and so much less heavy. I worked on the Mk2 Nimrod, based on the Comet, and I've heard tell that in its first incarnation it was bright aluminium because if they painted it the weight of the paint would have stopped it from becoming airborne. Interesting, but not a stored program computer.