I suggested that as a starting point for the cold war mod.
We already have a functioning snorkel mod for 1.5 . It seems to me all we need is a GUPPY sail modeled, outfit your boat with a load heavy with acoustic torpedoes from 1.5, and we are pretty well there.
I hope someone with some modelling skills (maybe Ducimus who brought us the new Tench model with the FM sonar head?) picks this up...