Sudden and uncontrollable loss of depth.

[Penta]

A WTF moment for the ages:

I'm playing 1.4. No boathandling mods, just graphic ones like Real Medals.

I exit brisbane for a patrol.

I make my way to deep water, hit P. I'm on unlimited batts and O2, prefer to travel sybmerged.

Now, I -just left- port. So ehen I hit P, why does it go past periscope depth and -keep sinking-?