Well, i introduced this routine. When the weather is fine (
) and night is in i reduce speed of my patrol to 4-5 knots and surface patrol, when the weather is bad i go submerged and go out to recharge batteries. At daylight i usually go with 10 knots. Indeed i was using high time compression but since i changed my routine i never had troubles. Still it's only September 1939, will play with lower TC as well from now on, just for good measure. I wonder if this routine will hold later in the war.
Cheers!