cacluating ship speed manually

[TorpX]

Originally Posted by Pisces

Just keeping the periscope at 0 or 180 degrees and turning the sub with the bow or aft right in front of the target also corrects for own motion completely. Don't turn while you take the time though, or twist the periscope. Make sure the compass is steady. But other than that you could go at flank (forward or backwards) if you wish.

This will work too.