I used to love submarine books when I was a kid.
One thing that I remember were the tense scenes where they were lining up an attack, and the elaborate manual systems for figuring out torpedo firing solutions, usually in real time. They had some kind of circular slide rule thing called an "Is-Was," and that goofy name is one of the things that stuck in my mind.
These were apparently obsolete even during WWII, replaced by analog computers.