[panthercules]

If you have decent visibility and the time to get set up for the shot, (and the target doesn't change course or speed) it actually is quite simple.

1. While surfaced and close enough to see the target without her seeing you, get your range and bearing to target (hard way = stadimeter in UZO; easy way = ask your WO); mark the target's location on your nav map, and start your stopwatch.

2. Maneuver on surface to stay close enough to see the target without her seeing you, keeping an eye on your stopwatch. As close to 3 minutes and 15 secs as you can get, get your range and bearing to target again and mark the target's location on your nav map again (as above).

3. Since any two points define a line, you can now simply draw a line on your nav map between the two target positions you just marked (extend the line out a ways beyond the target's most recent position marking, for convenience). If you aren't real sure about your position markings, start your stopwatch again right way (after getting your second position marking) and repeat the range/bearing marking in another 3min/15secs - that will give you 3 points and you can draw a line that passes most closely through all 3 points - it will be more likely to be accurate in that case.

4. The line you drew is your target's course, and the distance between the target position markers (the distance the target covered in 3mins/15secs, in .1Km chunks) is your target's speed. I.e., if your target went 1.2km between those position markers, the target's speed is 12 knots; if it went .6km, its speed is 6 knots).

5. Now plot a course that will take you up ahead of your target and wind up pointing you directly at the line of your target's course (i.e., so a line drawn straight ahead from your boat will hit the target's course line at a 90 degree angle), at whatever range you want to shoot at (usually between 500-1000 meters, though it doesn't matter all that much within reason) - just make sure to plot your course so that you stay out of your target's visual range while you are getting to your chosen firing spot.

6. A little before you reach your chosen firing spot, submerge to periscope depth and get your soundman to track your target on the hydrophones. You may want to pop up your scope every once in a while just to check and make sure the target hasn't changed course or speed.

7. You should set up your TDC at this point (manually). After selecting your desired tube(s), torp depth and speed (and spread angle if firing a salvo) and target speed settings, etc., first set your firing bearing dial needle to 0 degrees (assuming a bow shot here), then set your AOB dial needle to 90 degrees (port or starboard, depending on which side of your target will be facing you when it's straight ahead of you on its course line.) e.g., if your target will be coming along its course line from your left, its starboard side will be facing you and you would set your AOB needle to 90 degrees starboard.

8. If you look at the attack map, you should (unless some mod has suppressed it) see a dotted line that indicates the direction the torpedo would take if you actually fired it at your target when it was straight ahead of you. Of course, this line will be bending somewhat off to the side (the right side in the above example of the target coming from your left), because the ship will continue moving along its course line after you fire until the torp gets there. Depending on the target's speed (i.e., at higher target speeds), you might see that the target will get so far to the right before being hit that the angle of impact will be so small that you greatly increase the risk of a detonation failure. To address this (and here's the "magic"), just move/drag the firing bearing dial needle from 0 degrees toward the direction the target is coming from (i.e., to your left in the above example) - as you do this, you will see the AOB needle move to keep track of the correct AOB (so you don't need to guess at it) and you should see the torp path line on the attack map begin to straighten out until it points straight ahead or close enough to it to have a decent angle of impact close to 90 degrees. Depending on the target's speed, dragging the firing bearing needle over somewhere between 10-30 degrees toward the target usually works just fine.

9. Once you have dragged your firing bearing dial needle to where you want it (assume for the above example that you picked 340 degrees), open your tube door(s) and then you can just wait. Either by occasional visual 'scope checks or through your soundman, keep up with your target's bearings as they progress toward your pre-selected firing bearing needle setting. Just before your target reaches your pre-selected firing bearing, make a last look through the 'scope to ID your target's flag (if you haven't before) and make a last check to see if they look like they still haven't changed course or speed - then, when the target gets to your pre-selected firing point (340 degrees in this example), give the order - Los!

As to whether the range matters, as it turns out if you do the math you discover that it actually does not matter, as Brentano said, at least for a single torpedo shot (again, assuming your speed and course settings are spot on, and you have no issues like your torpedo running out of fuel or your target spotting the wake and having time to alter course or speed to avoid the torp). I had deduced as much from watching what happens to your projected torp line on your attack map as you dial in longer ranges on the TDC dial (i.e., it gets longer but its angle doesn't change), but I had to actually grab my calculator and crunch through some simple triangle formulas a few times to convince myself.

Obviously, if you fire a spread then the farther away the target the wider the distance between the torps will become at any given spread angle, increasing the chances that at least some of that spread will pass in front of or behind your target. And, as noted above, the effect of any errors you do make in the target's course or speed will be magnified the farther away you fire, so it still makes sense to bore in as close as you reasonably can.

Good luck and good hunting!