Good procedure for: bad weather, '43, enemy aircraft umbrella
 

I was practicing a little... three hours submerged at 2.9 knots, then 35-40 minutes (depends on the weather) surfaced recharging... it gives you 20 hours submerged and 3.8 hours surfaced... hydrophone and periscope sweeps before surfacing are mandatory...
This is optimum I think... you are slow as a snail but chances of survival are at least 50% bigger.
And yes... this was done in IXB with old batteries... i think the results will be even better with improved batteries.

Why haven't you bought a Metox in 1943.
As soon as it comes out-I buy.
Never leave home without radar detectors mid to late war.:salute:

Well I'm still in 1940... but as far as I remember there is a period of time when "they" have the radar and "we" don't have any kind of warning or snorkel device...:hmm2: and I don't like the idea of being caught on surface in 1943 and onwards... we need to turn our VII's and IX's types into at least Kilo class :D.