[Rockin Robbins]

Originally Posted by tmdgm

Here's my basic procedures when I use the stadimeter only, done this method countless times:

1) Take a range reading using stadimeter, click the send to tdc button (click only once). Verify the range updated on the left tdc window.
2) Take second range reading using stadmeter, click the send to tdc button (click only once). Verify the range updated on the left tdc window.
3) Go to speed calc and click on the button where it estimates speed.
4) Once speed (and course) is calc'd, I click send to tdc (click only once). THis is assuming the speed calc is fairly close to what I estimated on nav map. If it's not, I enter my own speed from the 3 min rule and hit send to tdc. Verify the speed updated on the left tdc window.
5) I go to angle on bow and adjust the ship to match the calc'd course on the left picture. Click send to tdc (click only once). Verify the AOB updates on the tdc window.
6) I then hit the red button to start tracking

7) As the ship gets closer, I will redo step 1 for range and sometimes double check step 5 for AOB.
8) I set torp depths
9) After final repeat of step 1 for range, I open torp doors, adjust torp angle left or right. Target is locked in sight.
10) Fire

Oh crap! That's what I was afraid of. Time for some explanation. The torpedo data computer plots a virtual target on your map. That is the impact point of the torpedoes. If your solution is valid, you'll see that impact point plotted on your attack map, an x on the stock game or the beginning of the targeting vector on TMO and RFB. What the TDC/PK does is move that virtual target in the same direction and at the same speed as the real target, changing the TDC settings automatically over time to hit it. Understand?

If you set up the TDC and then go to your attack map (use the button from your nav map screen in stock of just press F6 in TMO). There you will be able to watch the actual target and your virtual target at the same time. They should be right on top of one another, both moving at the same speed and in the same direction. If they are not, you're wasting a torpedo.

You've been wasting a lot of torpedoes. Why? Let's see what you've done.

1) Take a range reading using stadimeter, click the send to tdc button (click only once). Verify the range updated on the left tdc window.
2) Take second range reading using stadmeter, click the send to tdc button (click only once). Verify the range updated on the left tdc window.

Let's say our real target is out there traveling north at 10 knots. You do step #1. This is a two part entry, although you don't know it. You are entering the bearing and range of your target into the TDC. In effect, you've just told the TDC where it is. So it dutifully plots the virtual target right on top of the real one. Hopefully you're waiting longer than 30 seconds between step 1 and step 2 so you can get a little accuracy on that speed measurement! It is VERY sensitive to small errors and a longer length of time between the two readings helps.

So we have our virtual position plotted on top of the real one. Remember that because the zinger comes later.

3) Go to speed calc and click on the button where it estimates speed.
4) Once speed (and course) is calc'd, I click send to tdc (click only once). THis is assuming the speed calc is fairly close to what I estimated on nav map. If it's not, I enter my own speed from the 3 min rule and hit send to tdc. Verify the speed updated on the left tdc window.

OK, now we have our speed in the TDC. How long have you taken to do the speed stuff? Let's say about 15 seconds.

5) I go to angle on bow and adjust the ship to match the calc'd course on the left picture. Click send to tdc (click only once). Verify the AOB updates on the tdc window.

Looks good, you now have the target's course in the TDC. That step also took 15 seconds. This is important! You'll see.

6) I then hit the red button to start tracking

STOP RIGHT THERE PARDNER!!!!!! Your error is now in the system. Whatever you do from here on out doesn't matter.

It's vitally important what order you enter data into the TDC. Here's what happened. First you told the TDC where the target was. Fifteen seconds later you told it what speed it was moving. Fifteen seconds later you told it what direction your target was moving. Then when you hit the red button to start the position keeper, your virtual target finally began moving. Unfortunately the real target had been moving all the time. You are aimed 30 seconds behind your target!!! Ten knots is 1000 yards in three minutes, 333.3 yards per minute, 30 seconds is a 167 yard error. Your torpedoes are headed 167 yards behind your target because that is what you targeted. If it took longer to enter your data you will miss by more.

Always turn on the PK first. Then enter the speed and AoB, then lastly the range/bearing. The instant the TDC plots the position, it will immediately (and that is important) begin moving on the course and at the speed you input. Then go to your attack map. You'll see a time right next to the targeting vector. That is your projected torpedo run. If your virtual target and the real target remain superimposed for that length of time you will hit your target. If you only fire when that is true you won't miss.

Verifying your setup with the attack map is vitally important in identifying and eliminating targeting errors. Without using the attack map, you are only guessing. With it you know you have hits on the way. I don't know why nobody else teaches the importance of the order information is fed to the TDC and when you turn on the PK, but there you can see clearly why it's important and you now have a method of calculating exactly what the magnitude of the error is.