I just had this one and had to redo a career. That was an easy one to fix. I have seen this bug where no matter what speed I set, sub acted as if I was submerged and maxed out at 7 knots (even on surface). It corrupted something and any other sub of the same type (new career, training missions, ect) all acted the same way. None of the files I checked were changed to explain it and I eventually did a complete reload to fix it.
good luck,
__________________
----------------------
|