I'm pretty sure Japanese merchants of the time were taught "turn into a bow torpedo, turn away from a real torpedo" just like US sub captains were. There are examples of "turn this way training" like the ASW thing you mentioned and I believe some fighter pilots. I guess it would come down to a deck hand maybe having the presence of mind to scream "Torpedo attack, aft!" instead of "Torpedo attack!" in Japanese or just freezing up in disbelief.

Also I think the game makes the lookouts a little too vigilant with regards to spotting torpedo tracks and too quick to react both the crew and the ship itself physically. I was just simply trying to list plenty of "what-ifs" of factors that were present in real life that may not be modeled factors in the game or our gamer behavior.

Now for a 135 TTa shot yes turning one way or the other improves or worsens the target angular size but honestly both spoil the actual solution. If the target turns parallel to the torpedo track his angular motion goes from 0.707 to 0 or if he turns broadside his angular motion goes from 0.707 to 1. Either way he's not going to be where the torpedo expects him to be, the only difference is if it misses astern or passes alongside. Simply turning broadside is hardly the kiss of death.

I suppose that 0.707 and 0 are farther apart than 0.707 and 1 so turning broadside doesn't change the angular motion by as much as turning parallel. Also you figure that a spread of torpedoes are gunna cover a wide range so getting out of the way is not practical, you have to "turn slim." For a 150 degree shot the difference between turning 180 or 90 does the same thing.

I don't know of any real life torpedo shots that were purposefully aimed with the idea that "if the target turns left this'll get him." They simply fired spreads. Stuff like "angular target width 3 degrees, coverage 150%, maximum gap 67% = 3 torpedo spread 0,+2.25,-2.25."

I am not too good at this
 

If the 4600 yd line, the one that intersects the course line, does not start at my boat, where does it start? Where does it end? At the course line? And I assume my boat is on the 4600 yd. line. Do we need a different line if we use a different torpedoe speed?

Depending on where the course line interesects the 4600 yd. line, it will affect the distance. I understand using the target's speed to run up/down the target line to the firing point. I understand setting up the angle.

I assume we are not entering AoB in the TDC? Are we entering target speed into the TDC? Are we entering distance in the TDC?

I need this information so I can start at step 1 in this exercise. the math is beyond me.

"I plead igorance." Judge: Plea accepted.
 

I am still confused. Here are some simple questions. Some are difinition oriented. I consider other basic, so I can be sure we are not miscommunicating. I have situated the questions in the pararaphs relevant to the questions posed. I will not add my assumptions for what I think I should do, as they are likely erroneous. I do not want to make this more confusing to either you or me, or anyone else who might be unlucky enough to read this. I refer you to the examples in the post copied above. Assume I am using the Nav Map to draw my lines, courses and angles for purposes of these questions.

1. Assuming a 46 kt. speed for torpedoes, I draw a 4600 yd. bearing line that intersects the target's course line? If so, where does the bearing line begin and where does it end? Is my boat's location on that bearing line? If not, then where is it? Is my boats heading (true course) on that bearing line? If not, where is it heading? (Back to port? Just kidding.)

2. After figuring out the answers to questions posed in #1, I measure 500 yds. (i.e., the target's speed), and draw a line down the target's course line because the target is moving left to right?

3. I make an angle. An angle has two sides.

(a) The first side of the angle runs from the 4600 yd. bearing line? Must it run from my boat? Or from any point on the 4600 yd. bearing line? This side of the angle runs to its intersection of the target's course line. Can it run beyond the point of intersection?

(b) The second side of the angle runs from the same place as the first side of the angle. (Is that my boat? or any anywhere on the 4600 yds bearing line? or somewhere else?) and intersects the 500 yd. mark on the target's course line (described in #2 above). This intersection completes the angle and identifies the firing point of the torpodoes? The angle created is called the lead angle?

3. Assuming this angle is set up before the target crosses the intesection of the second side of the angle and the target's course line, I am now in position to adjust my periscope (assuming it is set to zero degrees) the number of degrees that corresponds (i.e. matches) to the number of degrees of the angle drawn on the Nav. Map. That is my firing point?

4. Do I need to measure measure distance? If so, is it distance to the point of impact or distance to the firing point?

5. Do I need to input AoB?

6. Do I need to input Speed?

7. I do not turn on the TDC by pushing the button to activate it?

Whew. If a response does not set me straight, I request reassignment for the good of the Silent Service.

I'm goin down.

The 4600 yard line(your course line) will start at the intersection of it and the target course line. EX. the intersection of the two red lines in the illustration.
It will extend 4600 yards from that point, passing through you boat at 0° and 180° if you are say 2000 yards from the target course line.

From the intersection of the two red lines go 500 yards (5kn.) towards the target Ex. the second red line where it meets the green line.

The green line (your lead angle line) is from the 4600 yard mark on your course line to the end of the second red line.

Measure the angle of the intersection of the red line and the green line at the 4600 yard mark. This angle will be your lead angle.

As the target approaches turn the periscope to that lead angle and shoot as the target crosses the wire.

Your boat can be any were on it's course line that is more than 500 yards(arming distance) and 4500 yard ( the range of the torpedo)

Target speed must = 0
AoB = 0
bearing = 0 and range does not matter. (For stern shots set the periscope to 180° and send bearing. Select a stern tube first.)
If they are not, set each to 0 and click send. You must have these at 0 no matter which method you use.

Do Not turn on the PK.

What you have pictured is O'Kane 90° and Cromwell 45° What I and Gutted are describing is actually vector analysis. You can be at any angle with V. A.

If you are at 2000 yards or less and have a big target you can approach at 65° +/- 1 or 2° AoB and your lead angle will equal the target speed, no need to draw any lines other than the target course line. Get a good speed reading and that speed = shooting bearing (lead angle).

This is very good for sonar only attacks, only be sure not to sink an Essex carrier. You may join another subsimmer on the rock pile. :rotfl2:
I won't mention any names but he has posted in this thread.

Magic

Funny you should mention it.
 

What a coincidence. Rockin Robbins just asked me if I know the name of the Captain whose boat sunk the Essex.:har:

If you want to use something like this for a sonar shot, when its dark and stormy and you cant even see your own bow (and you KNOW theres not an Essex out there :har: ) at what part of the bearing spread do you shoot at?

Okay!
 

Thanks Majic and gutted. That explanation, along with gutted pic, helps. I have been overthinking the method. I am off to try it out.

If you want to use something like this for a sonar shot, when its dark and stormy and you cant even see your own bow (and you KNOW there's not an Essex out there :har: ) at what part of the bearing spread do you shoot at?


It's really a timing thing and takes some practice. For single ships you can have the sonar lock on the target and fallow it to the lead angle shooting point. Try it a few times and you will get a feel for what spread and timing you need. Slow moving ships you can wait longer between shots.
Fast moving targets, such as an Essex, require faster shooting.

For convoys and task forces you can't lock on a single target so you must fallow the particular ship you want to hit and plot it's course to the firing point. It's a skill that requires practice but is a doable thing. Sonar sweeps take about 20 seconds for each update, so you must estimate the movement of the target for each sweep, again it's a timing skill you need to practice. Not as accurate as sight shot but still pretty good.

It's a handy tool if you have an escort that may detect you in good weather, I was at PD and id'ed a kongo BB but a DD was close so I went to 90 feet and shot from there. About 2800 yards in good weather and I hit 3 out of 4, and she went down. I shot right under the DD. THAT was fun. :yeah:

Magic

more questions.
 

Let's say the target is moving left to right at 5 kts. You draw a 500 yd. line on the target course to calculate the lead angle using the constant bearing method. Let's say the lead angle is 5 degrees.

If the target is not on that course, but closer of further away, running parallel, won't that change the lead angle?

@I'm goin' down: I've read post number 1 about a dozen times and can tell you there's absolutely nothing magical going on in this method. He's just setting up a "future" solution in the TDC and firing when the ships cross the wire. The heading to target (at moment of firing), heading of the boat, and course of the torpedo are 3 different directions which is why setting range is important.

293° bearing is just his "shoot course" or the absolute bearing to target when he launches torpedoes. This is why he has us keep pressing the "heading to view key" so we can place our periscope in the 293° true direction when our periscope has a 000-is-where-the-sub-is-pointing scale instead of the needed 000-is-where-the-north-pole-is scale. What's silly is that once you get a TDC solution you can simply mouseover the TDC window and read off the relative bearing to target for you solution eliminating the whole need to use that silly trick.

Honestly I find the concept of picking your shoot bearing out of a hat and then determining the gyro angle from that to be a bit backward. However if you must draw an arbitrary line from self to target track and then figure out gyro angle from that I could think of a slightly easier procedure.

1. Draw target track.
2. Draw shoot line from ownship to track. Length = range.
3. Measure angle from track to shoot line. Angle = AoB.
4. Measure angle clockwise from ownship heading to shoot line. Angle = shoot bearing.
5. Turn periscope to shoot bearing, drag range, drag AoB, drag speed.
6. Press Send Data to TDC.
7. Check result gyro angle is reasonable (000 +/- 30°).

It's pretty easy to see that this is just "What are the TDC data values when the target is at position X?" Oh, when the target is at position X its speed, range, bearing, AoB, will be this... enter. Sit and wait at 0 kt at periscope depth (realistic? :hmmm:) until target blunders perfectly into position X. Fire. Boom.

frederf
 

good explanation of setting up for the shot described in gutted's original post.

Back again
 

Hi fellow commanders!
I just came back from a long absence at subsim.com, and found an ongoing discussion about my little sharp-shooting tutorial which I wrote last year... Thanks to Rockin Robbins for answering many questions in the meantime.

Frederf is right here. I found out about that a bit time after writing my tutorial: You can read the relative bearing (where you have to point the periscope to) off the PK once you entered your solution, if you position your mouse exactly at the correct spot. Thus, no more need for the "heading to view" key which seems to draw so much discussion.

As I wrote in post #1, you can also easily read the relative bearing off the 360° bearing plotter on the nav map (just read the scale at the constant bearing line), if you have that mod installed.

Well, I liked the freedom it gives me, I can choose my constant bearing line however I like it beforehand. Of course, it simplifies matters and eliminates some possible errors if you set the line exactly at your sub's heading. Do that and you don't have to "wait at 0 kt at periscope depth", but you can actually move slowly forward (without turning), which is more realistic.

Correct, that's all it is about. Do it with some precision, and you get sure hits. This method gives you the time you need to do so.

A splendid method. Thanks for posting it:rock:

"113 degrees, add 180 for left (western) side -> 293 degrees."


add 180 for left side.. what would if the target was on the right side?

Did you really mean this? I am not grasping it. Every torpedo shot needs to lead the target, because it's moving. The amount of lead is a function of the speed of the target. Help me here.