Oxygen in the boat

[Doolar]

I've done a little messing around with the "Compressed Oxygen and the Oxygen in Boat" sliders. Got a realism question about the "Oxygen in Boat" times. I've got a few times written down while adjusting the slider on the HSie Selector panel. I know this is a estimate due many, many varibles. So with a TYPE VIIb or c and a crew of 45-50. About how much time was there with the Oxygen in the boat, before they had to release Oxygen from the compressed Oxygen supply ? thanx Jerry

[LGN1]

Hi Doolar Semler,

page 84 and 85 of the VIIC manual can give you some hints:

http://www.uboatarchive.net/Manual/Manual.htm

Best, LGN1

[Doolar]

b) Air purification system. The air purification system consists of: Purification system: removing CO2 by means of sodium hydroxide cartridges Renewal system: bleeding O2 from oxygen flasks. A man when breathing, creates 30 liters/hour of CO2 and needs the same amount of O2. The air purification system maintains the CO2 content at 1.5% level and O2 content at 17.5%. CO2 content above 2% is injurious. The estimation of time, when 1.5% CO2 content in 400 m³ of air in the boat will be reached: 37 men creates per hour: 37 x 30 x 100/400000 = 0.28% CO2 / hour So 1.5% CO2 content will be reached after 5 hours 20 minutes. The measurement of CO2 and O2 concentration is made by means of Orsat devices, first time after 4 hours of submerged cruise. Moreover there are CO2 sampling tubes to detect carbon dioxide content above 1.5%.

• my math is suspect, but I come up with about 4 hours for 50 crewman. If way off, I hang my head in shame ... lol

[RConch]

The longest hunt lasted over 40 hrs. The crew not on watch was to stay in their bunks to conserve oxygen. Active people consume more.

No boat could last with just 4 hours of Oxtgen.

[CaptBones]

The calculation is much more complex than apparent. Human lungs are not very efficient; you only absorb around 4% of the oxygen that is inhaled with each breath...96% is exhaled along with the carbon dioxide that the body produces. If not for the carbon dioxide problem, you could breath the air in a closed space for a much, much longer period of time.

As the technical manual indicates, in the real world, the oxygen content is not the major issue. It's the carbon dioxide level in the air that will first impair the crew and can eventually lead to death, long before the O2 content reaches a critical level.

The subject has been discussed many times before on the forum and the point to remember is that the game, including h.sie's "fix" does not deal with the CO2 content. The O2 depletion/replenishment mechanism can only provide an ersatz method of replicating the submerged endurance of the boat. The suggestions provided by h.sie, LGN1 and Stiebler in Section 11 of the MOD documentation results in the best approximation available.

I've found that setting the sliders to 1.5 and 2.0 provides 8 hours before the O2 level drops to 17%...with a crew of 44-46 and careful management of men on duty. If you're going to have a fully-manned boat, you should probably set the sliders to 2.0 and 2.5. If you keep everyone at battle stations, you're going to have to "max out" at least the renewable part.

[Doolar]

thanx all
I have the "Oxygen in Boat" slider set to 2.0 ( as recommended in the HSie readme, section 11 ) and I'm getting almost 9 (8h45m) hours before I reach 17%. Didn't know if that was too long a time to go before Oxygen was added. Again a type 7b/c and a crew of 50. I figured that's a lot of guys breathing the available Oxygen on the boat and I had no idea what a realistic time would be. I actually have never come close to exhausting my supply of bottled Oxygen, even when the slider was set to the default position. At the default setting, it takes me about 4 hours+ to get to 17%.