And heres me thinking the reason is I have to close the hatch first. I go down the ladder and like a good captain I close the hatch before ordering a dive. The first time this happened I had come across a destroyer firing at me so went to crash dive but nothing happened! Panic stricken and shouting curses while spamming the crash dive button. I then thought maybe I have to go down and close the hatch. Then it worked.
