I nearly always use sonar without periscope or range info, once I've ID'd the target. Range is irrelevant if you fire from the beam (limited only by torpedo arming distance and max torpedo range). Ergo, I use only passive sonar. You need only know the target speed, course, and correct firing angle. (e.g., 7 knots translates to an 11-degree firing angle if you're perfectly on the beam, and use a 36-knot Mark X; 9 knots = 14-degree firing angle). When the sonar man calls out the bearing of the approaching target, and it reaches the firing angle, I shoot. Actually I generally shoot about 1 or 2 degrees in advance, depending on how large the target is and how many torpedo hits will destroy it.
If you wait the 8 seconds or so for the "torpedo in the water" call, that generally translates into about 2.5 or 3 degrees of target bearing, moving across your bow.
Using the stadimeter, my torpedo accuracy was around 50 percent. Using sonar only, it exceeds 75 percent.
One caveat: zig-zagging targets are very difficult to hit this way.
Edit: so it was YOU who sunk the Essex?????
