How TO fire accurate with torpedoes
 

I wanna learn how to land them exac on ships(PLAYING U-BOATS) ... =) side moving or ahead to you moving ship.... Mb both ways with periscope&attack map(preferably on attack map while periscope locked) + i found out that type XXI can launch torpedoes from about 70-80 deep submerged...mb i can hit ships from that depth? like historacily XXI types cud do... by sonar or smthing dunno *_* i read they cud sink ships from that big depth's without help of periscope >_> .... Mb theres some utility that can tell where will be & when ship & torpedo as some time passes? Can anyone tell or give links?