Hello everyone. I don't stop by here much anymore, and was quite surprised people are still talking about Traveller mod. Thanks for the continued interest in it.
eers75 is correct. I edited the menu bars file to gray out the hydrophone buttons while surfaced. As he showed, it can be edited to allow surface hydrophones again if you so desire.
Regarding the convoy crashes, it is probably related to one more of the many ship files I edited when adding the sinking sound effects. I never could track down the exact cause of the crashes, but I do suspect it was due some of the ships I changed.