does your hydrophone work at all?

[Chock]

Have to wait a few seconds at persicope depth before it kicks in, then it works just fine, even works quite well while moving along fairly swiftly, although distinguishing stuff on a fast sweep is harder that way.

Having said that, I'm not sure how realistic this is, as I imagine it would have probably worked to some degree at any depth as long as the transducers were actually underwater.