In reply to wearymicrobe :
Despite what you see in the movies active sonar is pretty much the last thing done on a submarine as it tends to confirm you're in the neighborhood. Passive sonar was really really good even in the early 80's, the current Virginia class has passive arrays all over the hull in addition to the bow and towed arrays of previous classes. I'd be surprised if the Manta Ray has any active sonar capability.
