Personally I figure that's why I have a navigator, he knows how to do all that!
However, I do think it would be kinda cool if the accuracy of your position indicator on the map depended on having a clear sight of the sun or stars within x hrs or else you would start to drift off course (own sub indicator could fade like a lost contact).
Which brings up an interesting question... American subs' obs scopes could go vertical partly because they could be used for stellar navigation while submerged; I know the U-boats had obs scopes that could go to 90º elevation, but could they/were they used for stellar navigation?