I showed my CelNav routine in the video "Silent Hunter 5 Wolves of Steel: what is Real navigation in 2021" and in general it is similar to what derstosstrupp does:
https://www.subsim.com/radioroom/sho...62521&page=240
Of the two stars, one is usually Polaris to save time.
For calculations I use either F-Tafel or my excel spreadsheet "SH5 celestial navigation Sun, Moon, 58 stars" (this is an updated version of my excel spreadsheet "SH5 celestial navigation" included in C: \ Ubisoft \ Silent Hunter 5 \ The Wolves of Steel - Documentation \ Real Navigation \ RealNav - almanacs and tables by Alpheratz), which can be downloaded from the link in my signature.
I recently got acquainted with Fulst's Nautical Tables, which seemed to me quite easy to use (many thanks to derstosstrupp for explaining and showing me how to use them).