First welcome on board!
Calculate AoB with periscop is not very complicated and very very useful in manual targeting.
Let 's see it in images:
First, a 0° AOB, ship is coming directly to you
Now a 90° stb AOB
The left ship is 0° AOB, the right ship may be 2° stb AOB and the middle one 7-8° stb AOB
A 77°port AOB
As you see it's quite simple when AOB is near 0 or 90°. It's more difficult between 30 and 70°, in terms of accuracy. You have to "guestimate".
The only key is practice...
You can also determinate ship's course with only periscop:
Ship course= uboot course ( easy)+ periscop deviation ( easy) +180 (easy)+ AOB (if port) or -AOB (if starboard)
ex: uboot course:333 + periscop deviation +291 ( or -69) + 180 - AOB (cause it's starboard) so 333-69+180-10=434° as it is a 360° circle, 434° is equal to 74°.
Ship's course is 74, the only thing that is not known with absolut accuracy is AOB but here the supposed 10°stb AOB is very very close to the real value.
So now you can set up a nice 90° attack by changing course to 344
You don't need the map, don't need magical crew assists or auto updated bearing lines to perform it. Just look in your periscop!