Snorkel depth
 

I had my game modded for the US fleet boats to run decks awash by setting the snorkel depth to 7.8 meters, the command was the ; key. I recently reinstalled the stock game and now I can't remember how I activated that key. Any help here?

in data>cfg>commands.cfg you must assign the new key and in sensors.sim maximum height and rise time

If you actually have a snorkel then what he said is correct, if not only do the first part. Then go into each boats .cfg file and set the snorkel depth on the appropriate line.