There was a Real Navigation mod for SH3, with sextant and everything. The problem with SH4 is the question of what time it is. SH3's clock gave GMT (Zulu), the time at the Greenwich Obeservatory outside London, and if you hovered the cursor over the time it showed the local time, so you knew exactly where you were, time-wise. SH4 gives you the time at your base, and if you hover the cursor over the time, it gives you...the time at your base.
http://www.subsim.com/radioroom/show...ght=navigation
Dead reckoning works well enough, I guess. There is a mod that removes the sub icon from the map, so you can't see exactly where you are. That leaves room for being wrong. Of course if you are anywhere near land you have to make sure to look around a lot. I like DR for foggy days and when submerged, since it's much more difficult to know for sure.
If you figure out anything else, let us know.
