This thread says you can get it back if you use SH3Commander:
http://www.subsim.com/radioroom/showthread.php?t=119776
I don't play with it on myself as it's NOT something that anyone inside the sub could determine in real life. They could tell if they had a leak but not of the hull was likely to give way under less pressure than they may expect. I like the risk of not knowing how deep you can go.