@ Mikhayl
Stunning work

Great to have you back again!
@A6Intruder
You wouldn't have seen any exhaust smoke from the later model S-Boote - the engine exhaust ducts were
below the water line.
There is a close up photo of these in
Squadron Signal Warships No 18 : Schnellboot in Action (page 36).
Did you mean smoke-screen generation?