U-boats did not have the indicator technology during WW2 to detect their transition through the thermal layer. As Jimbuna said, SH3 Cmdr models this to some extent, but you will never know for sure. In the game, any depth will do for listening on the hydrophones, but in real life they dove deeper than periscope depth in order to eliminate the surface clutter noise. I feel that running at about 25 metres is a good concession to real world factors. I would advise that you wait until you are back in port before adding new mods, including SH3 Cmdr. It may work alright, but why take a chance? Once you do have it installed, use it to launch your game and exit the game at the end of each career patrol so that it can make the necessary changes in your career files.
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