Hadrys

I'm trying to collect precise info about navigating ships and especially u-boats. Were they using some special equipment to register their track or simple map plotting and celestial nav if possible? Quick maneuvers during heavy DC attack were rather hard to plot on map but also the distance made wasn't so big. I'm just reading Alistair MacLeans HMS Ulisses which might be not a great historical source but there is an "auto-navigator device" mentioned. Hard to find anything on google except V2 internal nav system but that was late war.

In general: how they did it and how exact was it. I'm into real navigation mod for SH3 to keep things even more challenging but need to collect lot's of info not to make it impossible... as I've just encountered recently going way off course during heavy sea state.

Best regards