In real life during the pre-war and early-war months, it was SOP to fire from up to 100 foot depth without use of the periscope, using sonar bearings only. That was the way the USN trained their submariners to attack. They feared the periscope being seen, as witnessed by the war games the USN conducted pre-war, where sub skippers received bad scores if they were seen.
There were multiple reports of success from US skippers early in the war, based upon the explosions they heard after firing via sonar targeting. However, in reality, they were usually hearing premature detonations of the torpedoes from the Mark6 exploder failures. If there were any "hits" accomplished by use of Sonar, they were few and far between. The only "witness" to success would have been the enemy. The USN quit using that targeting method early.
There are several methods you can use in the game to "target" via sonar, and the use of active sonar (pinging) is the easiest. There are several tutorials on the four-bearing sonar technique, but the original for Kuikueg's links are dead, even in THEBERBSTER's thread... Do an internet search on something like "site:subsim.com/radioroom 4 bearing technique" or "four bearing technique" and you should find several useful hits, but there is math involved in the technique...
- if you do it properly, your "hit" percentage will improve, but it is definitely much more difficult to get your boat in position if you do not use the periscope at least a little...
