Random crush depth

[Flaxpants]

I have this turned on in my options setting. I was wondering if this 'random' depth is defined at the start of the campaign, each time you leave port, or if it is randomised each time you submerge?

I went deeper than I had been before the other night- well into the red (not intentionally by the way, major flooding at the front of the boat started dragging me down) but my boat survived. If the random figure is fixed, then presumably I have a reasonable indication of what that crush depth might be, or at least I can define some 'safe' depths.

Whilst on the subject- What is the deepest depth you guys have managed to get a type VII without pressure damage?

F