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Breathe Easier

UPDATE: V 1.4

* Intended ONLY for use with GJC's Bigger Crew Sizes. For a version based on vanilla crew sizes, head over to : https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3312625205

* Update to match current Live Patch [2025.1.1 Patch 4]

- USAGE -

The mod requires a new game for the air quality changes to take effect, based on feedback.

-SUMMARY-

Brings more realism for ship submerged operations time and performance of the potassium filters used for atmospheric regeneration.

-THE WHY-

First, it is important to understand that the AIR QUALITY meter is NOT an OXYGEN meter. Think of it more as countdown to unlivable levels of noxious gasses such as - predominantly - carbon dioxide. The crew passing out and, if not dealt with, dying is not due to lack of oxygen, but from hypercapnia (CO2 buildup).

The vanilla game is setup to give the ship roughly six hours of submerged operations time before this happens. Historical records, however, clearly indicate that the expected submerged time was closer to eight to twelve hours.

Since the game has a very simplistic way of modeling this - a single atmosphere meter that encapsulates off these differing factors - there is only a single variable in the game files that controls this. To better reflect the reality, I have basically "extended" the meter itself to a base of approximately 12 hours (depending on exact crew composition and POWs onboard).

Secondly, the game only gives a single way of dealing with the CO2 buildup - potassium absorbers. In reality, there were several other ways to assist in atmospheric regeneration, but this is the one we have to work with (for, likely, the sake of simplicity). The absorbers, however, are far too weak to have any substantive effects on any given dive. The expected submerged time could, in theory, last as long as 45 hours (though there are some stories that say it could be up to 72 hours) before an actual lack of oxygen kills the crew through hypoxia... but since we don't HAVE an oxygen meter, we'll just have to make do.

I've done this by extending the working time of an absorber to 180 seconds, meaning that you can fully "recharge" your atmosphere with about three absorbers, giving you an additional 12 hours (roughly) of submerged time. Depending on how many you bring, that means a substantial extension of submerged operations if you need them.

- THE WHAT -

Two changes were made to the spreadsheets - any mods which make changes to these exact same lines will conflict.

1) Changed the vanilla air consumption rate to allow for the ship to remain submerged for approximately 12 hours. This can be extended if using "Blue Light" conditions.

2) Potassium absorbent values were altered to allow the ship to remain submerged for far longer. This was done by changing the operating time of a single item from 8 seconds to 180 seconds. This gives you the ability to completely recharge the atmosphere of your ship with two or three of them. Though I did not test the full extent of this, you could use this to help you remain submerged for up to 72 hours (possibly longer), though your battery will likely require you to surface far before that.

- THE HOW -

This mod was originally developed with an extensive mod list being used. With the Full Release only just happening, many of those are no longer relevant, but two in particular need discussion.

A) "Bigger Crew Sizes" (Created by GJC) - This mod has been tweaked to use this mod's crew size defaults. Altering this mod to give you larger crew sizes will result in lower submerged air time.

B) Device Energy Management (DEM) - This mod makes use of it's own Air Consumption system. If you intend for this mod to be in use, you will need to disable this portion of DEM. Instructions for this can be found in DEM's Mod Page.

- THE RATIONALE -

First, by way of background, I am a retired US Submariner, though from the modern era. That said, the WWII era is our heritage, and many of us spend a great deal of time studying that era and those boats - it's like looking up and researching your family tree.

The historical record is pretty clear - boats of this era could rarely afford to remain on the surface during daylight hours, especially later in the war. They had to be submerged, or they were essentially sitting ducks for any aviation elements that found them. The ~6 hour submerged operating time in the base game - while sufficient for more immediate tactical situations with regards to air assets - simply isn't enough.

Apart from the issues already mentioned, it also deprives you of other tactics against surface ships, especially the ability to wait out destroyers and other sub-hunting warships.

The absorber changes were made with the same ideas in mind, as many manuals of the time show an ability to remain submerged, using similar equipment, for up to 72 hours before they would be forced to the surface. Though I don't know that this mod will allow that long (depends on how many of them you stuff into your ship), this should now also be possible.

-EXPLOITS-

There are two potential 'exploits' that this mod makes feasible. I make them known so we can avoid futher comments about them, though both are there in the base game... and, really, one of them is, to me, more a 'last ditch damage control' situation. Use them or not at your own discretion - I'm not endorsing their use, just identifying them.

1) Indefinite Submerged Time. If you bring enough potassium absorbers, you can stay submerged for basically as long as those supplies last, no matter how long it is. This is a result of the aforementioned lack of separate O2 and CO2 meters. The reality is likely along the lines of 42 - 48 hours... I suggest disciplining yourself to not exceed that number, and even then only in an emergency of some kind. Your game, your call.

2) Infinite EMBT Air. Because you can completely recharge your atmosphere, it means you can pack more air into your HP Air flasks while still submerged... meaning you can use your Emergency Main Ballast Tank (EMBT) blow system multiple times if you end up stuck on the bottom deep. Not realistic, but a novel approach using the game's systems that - again - is there in vanilla, just not realistically usable. Again, your game, your call.

-COMPATIBILITY-

There should not be any compatibility issues outside the one noted above. Should one be discovered, drop a comment and I'll look into it and update as needed.

Special thanks to the people on the Unofficial Uboat Discord for their assistance in this mod's creation and testing.