[alboverburn]

Hi everyone, I did some testing to determine what was the fastest way to get under the surface.
There are four factors, in order of importance:
- type of command issued by the player
- initial speed of the sub
- decks awash
- overloading the engines

The type of command issued by the player has a huge impact on the time it will take to submerge.
Going at 11 knots and fully on the surface, issuing a dive command will take 45 seconds. Issuing a crash dive command two times will take 20 seconds.
The shortest submerging times will be achieved by having decks awash, max speed, commanding crash dive x2 and overloading the engines. I achieved 8 seconds this way.
Decks awash will decrease the time it takes to submerge, but not by much. In my opinion, if you want to conserve fuel (and get there faster), it's better to go faster rather than have the decks awash and go slow. You will submerge sooner by going faster than if you were going slower with decks awash.
Going at full speed will give short submerging times. If you need to submerge even faster, then go decks awash at full speed. It's pointless to go decks awash and slow (unless you want stealth).
There is also a difference between the UI button for crash dive and keyboard command. The keyboard command is much faster (from 40 seconds to 20 seconds).
Overloading the engines (with F9) after issuing the crash dive command can shave off 1 second.
The longest way to submerge is to be stationary, fully on the surface and issuing the "go to periscope depth" command. It took 1 minute and 15 seconds. In the same condition, but issuing the crash dive command twice without overloading the engines, it took just 27 seconds.
Results may vary from one sub to another, so I suggest to experiment with your sub to determine the optimum conditions and commands.


TLDR: press Shift + V twice (no need to release the shift between presses)