Can someone please correct “Seerohr” to “Sehrohr”? Also “Periskoptiefe” wasn’t used back then, “Sehrohrtiefe”. I’d also question looking for mines through the periscopes - are we sure this is feasible in real life?
I would also change “Geschwindigkeit” to ”Fahrt” when dealing with own boat speed or enemy speed. Geschwindigkeit was used for torpedo speeds but not the speed of vessels.