Will do Carrick and thanks for reminding me of another fun sim I hadn't installed for ages. One thing I did just re-learn was how to turn off the interface for a clearer view and a better screenshot, albeit I need to brush up on my U-Boat German as I much prefer the original language. But a tap of Numpad Del will bring the gauges back up in an instant.
I have a funny feeling the Steam version has some extras included, like the wood-framed stopwatch in my own pics which I don't recall in the original version. And I seem to recall that short of finding a mod, you could not lose the deck gun which was ditched by about 1943; but now, in single missions, I can select a wide range of different boats at different years, and for example get this late-war Type VIIC.
PS I think this may be the mod you had in mind:
http://www.thegreywolves.com/