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Steeltrap · 10-31-06, 06:06 PM

I've read of boats being under for 36hrs, but I believe that was the absolute edge of their endurance.

U-boats carriede potash as a means of scrubbing CO2 from atmosphere. They also had bottled O2 to be released in boat to offset the build up of CO2. It was not uncommon for a boat that had been under for a long period (say 24hrs) to have the hatch to the bridge virtually blow open when loosened due to the excess pressure from extra O2 being released, plus pressure from trim tanks (which were inside the pressure hull) being adjusted with compressed air.

I think it's Cremer who mentioned how the hatch being opened on one occasion resulted in a noise similar to what you get if you blow across the top of a bottle, only on a much greater scale. Said it sounded like a fog horn, and was worried anything for miles around would hear it!! Spooky.....

I also believe NYGM may have played with the CO2 to make it more of a factor in terms of being forced to the surface (ever notice your chief reports 'oxygen at 75%' even though the guage shows 0% CO2? I've never had a report saying O2 is at 100%). It's true that escorts later in the war would persist to the point of knowing the sub MUST surface eventually. Earlier in the war they didn't have the escorts available for it, and the lack of radar allowed subs to surface within 2-3000yds and escape without being seen if at night in any seas above calm.

10-31-06, 06:06 PM	#8
Steeltrap Grey Wolf Join Date: Mar 2001 Location: Sydney, Australia Posts: 818 Downloads: 3 Uploads: 0	I've read of boats being under for 36hrs, but I believe that was the absolute edge of their endurance. U-boats carriede potash as a means of scrubbing CO2 from atmosphere. They also had bottled O2 to be released in boat to offset the build up of CO2. It was not uncommon for a boat that had been under for a long period (say 24hrs) to have the hatch to the bridge virtually blow open when loosened due to the excess pressure from extra O2 being released, plus pressure from trim tanks (which were inside the pressure hull) being adjusted with compressed air. I think it's Cremer who mentioned how the hatch being opened on one occasion resulted in a noise similar to what you get if you blow across the top of a bottle, only on a much greater scale. Said it sounded like a fog horn, and was worried anything for miles around would hear it!! Spooky..... I also believe NYGM may have played with the CO2 to make it more of a factor in terms of being forced to the surface (ever notice your chief reports 'oxygen at 75%' even though the guage shows 0% CO2? I've never had a report saying O2 is at 100%). It's true that escorts later in the war would persist to the point of knowing the sub MUST surface eventually. Earlier in the war they didn't have the escorts available for it, and the lack of radar allowed subs to surface within 2-3000yds and escape without being seen if at night in any seas above calm.