CO2

[kptn_kaiserhof]

how do i decrese the rate of oxygen droping while underwater in my u-boat

[JetSnake]

Hold your breath

[irish1958]

Use your snorkel, or drop a few of your crew overboard. There is no other way.
irish1958

[Tikigod]

does anyone know if air on a sub is more compressed the deeper you go like it is when you scuba dive? In scuba diving your body consumes more air the deeper you go...decreasing the amount of bottom time you can have on a dive. In the case of a uboat if you were to run shallower does this lengthen the amount of airtime you have left? or was high levels of CO2 the the only concern for poisoning....rather than the limited supply of O2.

[GlobalExplorer]

No. UBoats were running at athmospheric pressure, thats why the boat is so much more vulnerable to water pressure. The need to make deco stops at the correct depths would have been to much in the way of submarine operation. Otherwise theoretically there would have been ways to increase the crush depth by pressurizing the interior.

[kptn_kaiserhof]

seriosly any one know how to slow down the loss of oxygen
because my u boat peforms like an akula

type ixd2
speed sufaced 20kts
speed submerged (no snorkel) 20 kts

torpedos 33
speed 200 kts
90kts homing torpedos

deck gun shells
ss1000000
he1000000
ap1000000

[Kpt. Lehmann]

Originally Posted by Tikigod

does anyone know if air on a sub is more compressed the deeper you go like it is when you scuba dive? In scuba diving your body consumes more air the deeper you go...decreasing the amount of bottom time you can have on a dive. In the case of a uboat if you were to run shallower does this lengthen the amount of airtime you have left? or was high levels of CO2 the the only concern for poisoning....rather than the limited supply of O2.

To a degree I believe this is true!!! (Especially in boats that have made deep or prolonged dives...

In Iron Coffins there is a passage that stated a man opening the hatch upon surfacing had his cap sucked right off his head...

That could be an exaggeration but.... lets think about this for a moment.

The deeper you go... the more your hull is compressed... (What do you think all the creaking and groaning is about?)

Even if the pressure hull is compressed 1/4th of an inch overall... the air-pressure inside the boat must go up!!!

Upon rising to the surface there is no guarantee that the hull will regain that 1/4th inch. (Crushing a can of coke is much easier than popping it back into shape no?)

So the air stays compressed until the hatch is opened.

I suspect too, that in sinking boats, crewmen in some compartments would suffer ruptured ear-drums before death... due to the onrushing water compressing the remaining air very quickly.

[Observer]

Originally Posted by Kpt. Lehmann

To a degree I believe this is true!!! (Especially in boats that have made deep or prolonged dives...

In Iron Coffins there is a passage that stated a man opening the hatch upon surfacing had his cap sucked right off his head...

That could be an exaggeration but.... lets think about this for a moment.

The deeper you go... the more your hull is compressed... (What do you think all the creaking and groaning is about?)

Even if the pressure hull is compressed 1/4th of an inch overall... the air-pressure inside the boat must go up!!!

Upon rising to the surface there is no guarantee that the hull will regain that 1/4th inch. (Crushing a can of coke is much easier than popping it back into shape no?)

So the air stays compressed until the hatch is opened.

I suspect too, that in sinking boats, crewmen in some compartments would suffer ruptured ear-drums before death... due to the onrushing water compressing the remaining air very quickly.

No, no, no! You can believe what you want, but it would be fundamentally wrong on multiple levels!

As the boat submerges the hull does compress, but it has a negligible impact on atmospheric pressure inside the hull. Being inside a submarine is nothing like SCUBA because in order for a diver to inhale at depth the supply pressure must be greater than the current dive depth (44 lbs/100 ft or 1 atm/33 feet). All the physiological side effects aside due to the partial pressure of oxygen and nitrogen (Oxygen being more of a concern when breathing Nitrox), it's why the tank empties so fast at depth (roughly 50 lbs every breath when at 100 feet...that will empty a 80 cubic foot cylinder pretty quick).

Submarines on the other hand don't have this problem. The atmosphere is about 1 atmosphere or slightly higher. Interestingly the concentration of CO2 in a submarine (CO2 being the chemical trigger in the lungs to stimulate breathing) is about 50 - 100 times higher than atmospheric. The best way to minimize the effects from CO2 and CO is to increase the pressure in the boat. Submariners call it taking a pressure on the ship. 688s doe this using the low pressure blower. Uboats could use the diesels, but it would be a tricky evolution. In either case taking a pressure on the boat reduces the partial pressure of CO2 and therefore minimizes the negative effects (fatigue, lethargy, headache) of CO2.

Pressure in the boat can increase due to several other routine evolutions, but the most common is venting high pressure air inboard. This can happen, for example, when firing the torpedo tubes.

The fact that the sailor had his cap blown off indicates the pressure in the boat was greater than atmospheric, and when the bridge hatch was opened, the pressure equalized. There have been cases of sailors opening hatches before equalized to atmospheric that literally shot the sailor out of the boat in some cases severely injuring or killing the sailor.

[vonBimmell]

The pressure inside a diesal boat is always at atmospheric. The only thing that changes the pressure is when you are snorting, and the float valve in the snort induction mast shuts when a wave goes over it. The diesals suck all the air creating a vacuum. When this happens, it feels like your brain is being sucked out through your nose.

It is worse when you are sleeping, and have been snorting for awhile. Your ears dont clear automatically, and when you wake up you feel like you are in another dimension from the pressure build up. Then when you do val salva to clear your ears it feels like your brain explodes. Then you have one hell of a headache for awhile.

Over time you do get a slight build up of pressure in the boat, and if you have been running shut down, when the hatch is opened when you come alongside, you can feel the pressure in the boat equalize. I have never seen it strong enough to loose your hat, but I guess it would be possible.

We used an oxygen candle which was activated by a 410 guage shotgun shell, and gave off oxygen as it burned to enhance the air quality when dived for a long time, and we had a CO2 absorbtion unit in the fore ends, and one in the after ends to get rid of the CO2 buildup. I don't know if U-boats had this, but the O-Boat I served on was not that much further advanced, so it may have been possible in some form.