well im no ace of the deep and i just do things my way. When i get message about ship spottet i dive engines of head to sonar. There i plot bearing every 30 secs, mark it on map. Then i have the direction. Then i look through scope, checking again, using the lines in the scoope and the stop watch, that gives me s0ome speed details. Combining those two i head to the map, create the intercept. Wait to the ship is almost out of distance in the scope, surace, racing to the intercept.
I dont use all the fancy math, im a janitor, not a professor
my stats in hitting are about
suuuux % hits. For some reson n9o matter what i do i need to fire 3 torps to get one hit. This have not changed in 4-5 years, i can hit i just need 3 shots

..and i have been reading, practecing etc, but it never fails. Manual TDC = 3 shots for a kill..(moving ships)..
So i kinda just do it on the experience since my janitor brain simply cant figure out 1 shot one kill