[Erasmus]

I am sure they shield it well, but wouldn’t the resultant EMP make the ship just a bit harder to hide?

Possible. Although opposing forces would have to come up with specific detection systems for it, which I am pretty sure nobody has implemented.

The closest type of detection system currently existing would be one of the networks of lightning detectors/locators.

I'd like to think that the E-catapult designers have thought of this already, but who knows?

[The Cajun]

Possible. Although opposing forces would have to come up with specific detection systems for it, which I am pretty sure nobody has implemented.

I think regular old sonic signature detection would work. I mean a jet being flung backwards off an aircraft carrier and the jet exhaust hitting the water backwards should have a unique sonic signature.