Floater, also I've had situations where I'm on the bridge in binocular or uzo view and have seen a ship come into view with no problem. The bridge watch will be silent. Once I leave the bridge view suddenly the watch comes out of their coma and sees the ship. Hasn't happened often but when it does it's irritating. Same thing occurs at the sonar station.
I guess chalk it up to a game inconsistency(that's a polite word for GAME BUG)