Does the nav subsystem serve any purpose?? I thought it might prevent the player from jumping out, but when my nav got scragged the jump drive still seemed to work. I'm just wondering whether its a useful system or not.
I think it's more for plot-based elements than for anything else; I know I've jumped out while it was destroyed without any problems. It would be interesting, though, as a FREDder, to create a mission failure if the player jumps without having their nav system repaired; after all, by doing that, you'd most likely wind up in the middle of nowhere.