Definitely not an accurate rendition in SH4. The US boats, while bigger, also had a much bigger crew, and did not have a scrubber like the German boats. All had an O2 "bleed", where they could put O2 from tanks in the atmosphere, but that did increase the internal boat atmospheric pressure. But they could stay under for more than 24 hours also. The main problem with the SH4 game is that the warning message pops up, but that's all it is - a warning... it is colored yellow. The actual "you have to surface" message is in red and says something like "CO2 level is critical", and you do have to surface pretty much immediately. The warning message could actually say something like "Smoking lamp is out! CO2 level is getting high", then have another, the "warning" message, about 1/2 to the critical... that would be more useful... but alas, they have those two triggers, and that is it. Of course, it behooves the skipper to stay on top of the situation and make the decision for himself...
