Crush depth question

Was practicing on one of the GWX missions (night attack on convoy in indian ocen I believe) and I picked the Type 7c/42 sub to play with. After a successful submerged attack on the convoy I was attacked by a corvette. I dove down as far as I could (can't remember the depth) and soon after got the death screen.

My question is does each boat have seperate crush depths, or are they all the same no matter what boat?

Regards...