CB -
Observations
1) Dropping the hydrophone Min Range from 1000 to 600 seems to have had a nice result. I'll have to play with it more, but it seems to give them just a little bit more of an idea where you are. It gives them a better chance of causing some damage.
2) I'm kind of worried about their hydrophone performance in storms. I think it's a little too good. It seems that they can hear me on the surface (since you often drop below the Max Height of -10m in storms), and it does seem a little odd to me that they can get my position despite huge waves while I'm at periscope depth. Maybe time to re-introduce a bit of a wave factor?