Eh, not really. Synthetic Aperture Radar satellites used for marine ship detection have extremely wide sensor swath widths, and ships show up as very bright radar targets against the ocean. Detecting a large ship, even in a very large search area, is almost trivial.

Identifying a ship is harder, but not insurmountable. In particular, large ships like aircraft carriers tend to have very identifiable radar signatures if your resolution is high enough.

>if you don't know where to look

I mean fuck, I can pretty easily find the strait of hormuz on the map, pretty sure intelligence agencies can too and just look there for the carrier. If I can't find the carrier there, then I can plot the course between France and hormuz and do a brute force search over that course taking into account such a ship's relative velocity, since it's not like the carrier is gonna zig-zag through south america and the north pole on its way there to avoid detection. Is what I'm saying something sci-fi?