The hydro guy can only give information (and follow) the nearest ship. Not the other, if this other is further!
So when 2 destroyers are around, i only know what the nearest is doing, not the other (is he approaching too, or running away?)
Using real nav, we don't have contact lines to estimate the movment of ships...we can only rely on the hydro guy with his informations...but when more than one boat around, it seems impossible to me so far.
And estimate ship movment (closing/running away) by myself using hydro is still too hard...
__________________
|