Another topic, diving speed. A super cruiser miraculously appears from the 4th dimension coming toward you at warp 9, firing from three hundred 95 inch cannon simultaneously at 38,000 rounds per minute.
Obvious thing to do is dive, but conventional wisdom has it that fleet subs were slow divers because they were bigger than U-boats. I timed a "standard" dive (no such thing in wartime, they were all "crash dives" even if it was just for practice) and it took 2 minutes to get to periscope depth. Order crash dive and it took a little over 1 minute to get the entire sub including the stern flag staff under.
From a wiki article;
The Gatos were slow divers when compared to some German and British designs, but that was mostly because the Gatos were significantly larger boats. Sufficient fuel bunkerage to provide the range necessary for 75-day patrols from Hawaii to Japan and back could only be obtained with a large boat, which will take longer to submerge than a smaller one. Acknowledging this limitation, the Bureau designers incorporated a negative (sometimes called a "down express") tank into the design which provided a large amount of negative buoyancy at the start of the dive. Normally kept full or nearly full at the surface, the tank was emptied to a certain mark after the boat was submerged to restore neutral buoyancy. At the start of the war these boats could go from fully surfaced to periscope depth in approximately 45–50 seconds. The superstructure that sat atop the pressure hull provided the main walking deck when the boat was surfaced and was free flooding and full of water when the boat was submerged. When the dive began the boat would "hang" for a few extra seconds while this superstructure filled with water. In an attempt to speed this process, additional limber, or free flooding, holes were drilled and cut into the superstructure to allow it to flood faster. By mid war, these measures combined with improved crew training got dive times down to 30–35 seconds, very fast for such a large boat and acceptable to the boat's crew.
With that in mind (Run Silent Run Deep fans will remember the constant drills Clark Gable ran to get from surfaced to periscope depth and ready to fire in 35 seconds) I started playing with the \Data\Submarine\NSS_(subtype).sim file.
At the bottom 10/11 unit submarine is the last datablock, ballast.
mainBT flood speed = 20000
DiveBT flood speed = 9000
Is Diesel-Electric = true
Last line doesn't affect anything about diving speed, but after more trial and error I came up with;
mainBT flood speed = 38000
DiveBT flood speed = 18000
Is Diesel-Electric = true
With those numbers, cruising at 15 knots with tanks blown dry fully surfaced;
Periscope depth
hull under in 30 seconds
top of conning tower under in 45 seconds.
periscope shears under in 1 minute.
level at periscope depth 1 minute 10 seconds.
Crash dive
hull under in 20 seconds
top of conning tower under in 35 seconds.
periscope shears under in 45 seconds.
level at 120 feet in 1 minute 5 seconds.
I know not what course others may take, but as for me that feels more realistic than having these drunken lubbers lollygagging around for 2 minutes under fire while Mister Panic screams about all the damaged systems at an auctioneer's speech pace.
What I would really love is more control over buoyancy - real subs had dozens of tanks, in addition to the main ballast tanks being divided there are assorted internal trim and buoyancy tanks. Got flooding in the after torpedo room and can't stay level, pump from the after trim tank to the forward trim tank, give me a 20 second blow in 6C and 6D to put a bubble in those tanks. Can't maintain depth, pump from safety to sea 5 tons. This all or nothing design for one of the most important aspects of controlling a sub is pretty lame.