[TorpX]

I presumed the notion of CL's having sonar (or depth charges), was so that they could provide an inner defense for the capitol ships they were escorting. That is, enough charges for one or two runs, just in case.

you think? You just have to clear the escort screen, and big ships won't have any idea of your possible location....

Aside from the points already stated, BB's, CV's, and CA's having sound gear and listening would do them little good. If a sub is quiet enough for you to get through the better skilled escorts, the odds are the big ships wouldn't hear it anyway. They would be pointing their hydrophones out and constantly picking up the noise of their own escorts, and the other capitol ships.