Speed isn't so much an issue as aircraft will find you regardless. The radar is really that good. Between March and Black May is when the new radar sets start coming out. There is about a 9-month gap between that and the snorkel. Your best bet is to run submerged for three hours, surface long enough to top off batteries and repeat. Even then, you still may be jumped by aircraft. The idea is to minimize being on the surface as much as possible.

I'd have to double-check, but since I use the no fatigue model, I haven't noticed. The problem with the snorkel is that most had faulty floats. They would either stick open (flooding the diesels and the sub) or stick closed (smothering the crew). When the float would open and close normally in poor weather conditions, the diesels sucking the air briefly out of the compartments would cause painful pressure changes in the boat that would strain or rupture the eardrums of the crew. This is probably what you are thinking of regarding the modeling.

I know... I'm not trying to runaway from aircraft, I'm asking how fast you drain your batteries, i.e. how fast you are moving when submerged? If you are moving at flank speed it would mean that you have to stick your snorkel out every hour or so...
9 months :o... holy ****! Loooong time to die with a stupidly-surprised look on your face!

When submerged, I never exceed 3 knots except in extreme circumstances. I can usually make it from dawn to dusk on around 40% of a full charge. It takes me forever to get anywhere, but at least i get there. :D

Yup thats wat i meant ;). I think NYGM might model that, ill have to check the Manual..