I don't think there was an attempt to "model" much of anything close to reality in the game, just an attempt to control desired aspects somewhat realistically. Most of the numbers used are just "modifiers", and not actual numbers. Unfortunately, you end up with one setting affecting the others in related areas, and also in seemingly unrelated areas, so that if you change the range, you might change the actual speed the boat travels at, and / or its 'efficiency' as far as fuel usage goes, both for diesel and electric, plus maybe influence the charge times. Myself, I've never tweaked much in the sim files, and left that to CapnScurvy since he's a more experienced modder, by a long shot. But you can do what you want, since it is your game. Tweak to your heart's content. Doing so does make it more difficult for us to track troubles you might encounter, but it's not the end of the world if you alter things...
I would suggest though, that you build yourself a mini-mod for each aspect that you want to experiment with, so that if something fails, you can easily rollback your changes. In other words, create a folder in the MODS folder, and name it like "SBoatEdits". Under that, create a "Data" folder. Under that, a "Submarine" folder, and under that, an "NSS_S18" folder (or which ever boat you're modding). Then copy the sim file from the game over into the new folder you made, and edit it how you think will be good, then "activate" your mod, and see how it works. If it doesn't, or you want to change it, just back off the mod, do more edits, and re-activate it. If you find something you like, let us know, and we can "certify" it for you as an "official" FotRSU mod to share with others, or even incorporate it into the mod, if you want, giving you full credit for the edits, with your permission...
As a side note, you might notice in FotRSU (stock is similar) that the S18 has 17 files in its "Submarine" folder, while the S42 only has five. The S42 uses the main files of the S18 for its 3D build, such that changes you make to the S18 are also reflected in the S42, unless you alter the eqp, or sns, etc files. The S42 is a small clone of the S18 boat. They both have separate sets of cfg files, but share the same 3D files.
