I know that considering whether a submarine can swim is part of a useful philosphical observation[1], but I've never heard any discussion as to whether they can sign their name. Or maybe you means something else which you haven't bothered to tell us.
[1] "Asking whether a machine can think is about as useful as asking whether a submarine can swim"
FEKO is reasonably good for estimating electromagnetic signature in the form of RCS for aircrafts and ships.. not too sure for under-water electromagnetics.