I did it during "invasion of Poland" so I couldn't look at maintenance. However, I didn't get any flooding or any shouts from my crew about damage so I assumed it wasn't major damage.

The real test is whether or not this state can be maintained during time compression. Or whether the seabed inflicts compounding damage the longer you stay on it. Ithink many submariners will gladly take that 1% hull damage and no machinery damage for the ability to sit on the bottom in prep for an attack / to evade an ASW patrol.

Ah, true. I'll test it out later less someone beats me too it. If it doesn't do anything to hide you from active sonar, to me, there really is little reason to worry about it, I wont be bothering. I really just wanted to see how much I had to worry about hitting the bottom/how deep I could go depending on which came first.