Having been a Navigator and an XO and a CO starting back when we still relied on celestial navigation as the primary means of getting from Point A to Point Z and everywhere in between, I can vouch for the accuracy needed to keep your job. A 5-mile triangle for three Lines of Position meant you had to go back and start over; 3 miles was good enough (barely) and if you couldn't consistently hit 2 miles you were due for a refresher course in shooting the stars. Yes, we had LORAN and we had one of the first versions of SATNAV (yeah it was called that at the beginning, not NAVSAT, that came along later). But real navigators took pride in doing it the old fashioned way; if for no other reason, that everything else could and often did, fail. BTW, any "Navigator" who couldn't hit a harbor entrance on the nose was sure to lose his job as well...you can start your radar coastal nav plot well out to sea, especially if the coast is mountainous and/or there are offshore islands to get good returns off of.
Back to the OP though, one of the more "realistic" ways of operating your boat in the game is to pay attention to what the Navigator needs in order to get good positions and maintain an accurate track. You have to be surfaced for morning and evening stars and a sun line at Local Apparent Noon...weather and enemy ASW assets willing. Depending on the weather and the season and latitude, morning stars should be taken from 30-60 minutes before sunrise and evening stars from 30-60 minutes after sunset; Local Apparent Noon should be obvious...as long as you know your approximate longitude and your chronometer is in good working order.
