Hello,
keeping depth has to be monitored, even with an experienced crew - when i took my VIIC to 200 m i decided to let it glide on that depth at slow ahead, then went away to get some coffee - coming back the boat was at 220 m
. I ordered periscope depth but the speed was not enough to raise the boat, the bow raised but the speed dropped to one knot, due to more drag caused by the raised dive planes - the boat even continued sinking slowly. At this point you can only go to half ahead or blow the tanks (once) for getting to the ordered depth or even keep the current one. The devteam knew what it did, or so i feel ...
Greetings,
Catfish