Hmm...
From 2.0 testing... The IIA would not go down further than 150m anything over and that and it starts to crush. The IID is a different story. STronger hull, I do believe I got a IID down to about 190m before it started to crush..
The beauty of the type II is in fact its size. It doesn't need to go as deep as its larger type 7 and 9 sisters because it presents a smaller return anyway.
Getting depthcharged in a type II is a treat!