So long as your Steam game install is in its own "library" folder, you're fine. The last time I tried on my Steam stuff, I couldn't get v1.4 to "stick" in the Steam SH4 v1.3 folder. I have Steam SH3 & 5 also, and have to be very careful with their new "security" stuff, or else it'll wipe-out mods, even when not in the Program Files folder, but just from the Steam "updates". I do not use my Steam SH4, since it's such a pain, and I've got two disk versions of it (actually, 3 disk versions, but I can't find my original, nor can I find my original SH3 disk -
)... I don't know what to say about the erratic sonar ranging. There is some "slop" built into it in the game for "simulation", but I don't recall it being ~that~ bad. Try a mod, like TMO, that alters the figures, and see what happens...