robj250 opening the doors manually its not a biggest problem hiting and sinking a destroyer, you dont play with manual target solution am i right? Here is my personal tip.
Spot a destroyer, take a aprox.90 degree course to make a good fiiring position (i am sorry my English need improvment)
Now since you dont have to calculate aprox speed of the darget
go to TDC set 2 torpidoes to fire - you may also use 3 if you wish
set the depth to 1 meter - fast speed impact pistol
now set the giro angel between 5 or 6 depends how fast the destoyer travell.
open toobs - and LOS!!!!!!!!!!!!!!! :rotfl: