Hi
For SH5, you shouldn't relate SH3 details. I don't know, but doubt the developers were being so exact as to what rpm's you need. Anyway, you can get a good idea by just ordering silent running. See what speed the game goes to.
My understanding is that, besides slowing down, no repairs will be made, the torpedo loads stop, and whatever numeric 'noise' value those items added to your sub detectability percentage is subtracted.
The whole thing is a calculation based on numbers for each item. Programming is just a bunch of numbers,such as probability calculations.
So, order it and do some investigation on what the game does for you.
