Thanks for the info severniae, I've got to try this mod out! It's a very difficult task to use the stadimeter (even if it wasn't faulty), especially with UZO; even when the sea is calm, it's almost impossibe to keep the target within the view. 100% realism, that is.
I still use a manual charting methods (=determining target's speed and course) first introduced for SHIII
(LINK). For manual targeting I used the "Wheel" method, but as the pictures of the wheel haven't been available for a long time I had to make one by hand

After that I discovered another Wheel target system by CapnScurvy somewhere in SH4 forums (lost the link), and while the principles are the same as above, for some reason I prefer the latter more.