Snorkel - Is it in the game?

[Snacko]

Is the Snorkel for allowing the sub to run on deisel underwater, getting it's air from the snorkel tube above water? Not sure if I got that correct...

If so, is it in the game? I don't see a key for it...

What are the standard cruising procedures to a target area? I try and stay under during the day, and surface at night to replenish my batteries. If I need to surface during the day, can I just use the snorkel to run on deisel, replenish my batteries, and get oxygen and expel the Co2?

I am running at about 30 realisum, with the checkboxes checked for real Oxygen, Co2, Fuel, and Batteries. But the red battery scrollbar 'never' goes down. Neither does the Oxygen. But when I surface, a crew member immediatly tells me "Captian, we must surface, we are out of Oxygen."... Why does he always wait until I decide to surface?