Basic question re the TDC in ATO/KIUB mod

[I'm goin' down]

Here is a copy of a portion of a PM exchange between Wilcke and me. It illustrates the issue I am having with KIUB.

Captain Wilcke:

"Ok, its technique, you need to see a video of the shot, once you see that the KM KiUB is a lethal point and shoot.

Once I have course and speed, I go ahead of target and setup 800m at a 90 degree angle to targets course. If its a port shot, I set the periscope 15 degrees off my bow to the right, towards the approaching target. I then turn off the TDC by pressing on the edge of the blue light, set AOB to 75 degrees port( 90-15=75), set my speed and range dials appropriately, turn the TDC back on, blue light is lit.

I setup my torpedos and I can sit and follow the sonar mans calls until its time for me to shoot. When ready I raise the scope and wait for target to cross the periscope wire and shot for the king posts, two shots and your done. Down scope and wait for the boom.

The thing is so accurate, that if I have one hit and one dud, I just turn the TDC off adjust the speed for the slowing target turn it back on and re-aim the scope just a bit ahead of the now slowing target and shoot for the kingpost that did not get hit. At this range even after the target has crossed your bow and is moving away the TDC can still hit at 800 meters.

I have to find a tutorial, even an old one would work for you."

My reply, which pretty much says it all:

"Here is my question. In your example, you point the scope to 15 degrees (target's port side), deactive the blue light (which turns off the TDC) and set the Aob dial to 75 degrees. The next part of your explanation confuses me. If you reactive the TDC (turn the blue light on), won't the TDC begin tracking the target even if it has not reached 15 degrees (i.e. say the target is at 20 degrees when you reactive the blue light and at that bearing will not cross the wire until it reaches 15 degrees.) In PTO the TDC still tracks the target when it is in the deactived positon (i.e. the PK is turned off). In OM, by contrast, you are advising to turn on the PK, and apparently you are indicating that the TDC will not move if the periscope remains 15 degrees. And, what happens if, after the forgoing is set up and the periscope is moved to a new posiiton, say 5 degrees?"

It seems from Wilckes explanation that the TDC locks on the target at 15 degrees but does not track the target. This seems to also be what Capn Scurvy says in his tutorial on the his brand spanking new OTC mod, where he notes that the German UBoats did not have a Position Keeper to update the TDC. If this is correct, then tracking a ship on the TDC in ATO is not possible. In such as case, Wilcke's attack instructions, i.e. shooting when the target crosses the wire, are pretty much the preferred attack method. Kasmaronov (spell?) talks about firing with a zero gyro angle, but I will deal with that method when I understand what is going on with the TDC. So far I have not hit a moving target. Also, assuming Wilcke is correct, is the preferred target bearings for an firing torpedoes between 345 and 15 degrees? Or can an attack proceed at other angles?

BTW. I saw a one hour special on the Battle of the Atlantic. It dealt with Doenitz's wolf packs in 1943 and 1944, UBoat limitations, allied countermeasures to the various German submarine tactics that evolved in response thereto, plus interviews with German, Canadian, British and American sailors and sub hunting allied pilots who lived through it. This was the turning point in the Battle of the Atlantic.

By the time Doenitz incoporated the snorkel so his boat would not have to surface frequently to charge batters, and the German introduced better armored subs that could dive deep and were more likely to survive depth charges dropped from destroyers and aircraft, it was too late. The casualty rate for UBoat crews was 75 percent, the highest of any branch of the German armed forces. Doenitz was designated fuhrer by Hitler when he committed suicide, and succeeded Hitler. He did not believe he had done anything illegal, but was sentenced 10 years in prison for war crimes. The special did not detail the crimes against him. The special describes him as a committed Nazi, and pointed out that he was highly respected by his submarine corps throughout the war. His son was killed aboard a UBoat which was sunk in the Battle of the Atlantic.

The special takes the position that the allies were open to using ideas from any source to develop countermeasures to new UBoat tactics, but that the Germans did not. This diffeernce may have led to the ultimate defeat the UBoat fleet. For example, when UBoalts introduced magnetic torpedoes, which homed on a target's propeller, the allies countered by dragging a line behind their ships with an attacked device which created a great deal of noise and was intended to confuse the incoming torpedoes. The magnetic torpedoes went to for device, and ultimately proved to be ineffective. This was a simple, creative and low cost countermeeasure.

One interview with a German sub survivor was really interesting. His sub was sunk when it tried to enter the English Channel by sailing near the bottom of the Channel. His boat was part of the UBoat fleet sent to thwart the D-Day operatoin. Allied ships hunting UBoats had great difficulty tracking subs sailing near the ocean floor because it confused their radar (due in part to the presence of a variety of materials on the sea floor that reacted to radar signals.) The survivor escaped the sinking by dawning his oxygen mask and exiting the sub through a torpedoe tube. He was the only survivor of the sunken sub. He said on the way the surface he relived his entire life, every moment. He said he could not describe the experience or say why it happened, except to say that it was a real as the person sitting in the room with him doing the interview.

[Fincuan]

I'll play a bit of Mythbusters first:

• The German TDC doesn't have a PK
  CONFIRMED, there is indeed no PK.
• The American TDC tracks even though the PK is off
  BUSTED, it does not track if the PK is switched off. That's the whole purpose of switching it off.

What the German TDC does is give you the correct lead-angle based on your speed, AOB and inputs. It does not actively track anything.

Doing all the 75 degree things just makes it all seem overly complicated, while it really isnt't. The technique mostly used with the German TDC is commonly called "Fast-90", and has been around at least as long as SH3, probably even longer. One way to do it:

• Get to a position 500 - 1000 meters off the target's track, at a 90 degree angle to the track.
• Point your scope to 0-bearing if your bow is pointing at the track, or 180 if it's your stern pointing at the track.
• Disengage the scope from the TDC, ie. "turn off" the TDC. This is the famous button with a light.
• Input target speed and approximate distance to the track at the moment of firing. Distance doesn't need to be all that precise if you fire as close to 0-gyro angle as possible.
• Turn AOB dial to 90 degrees port if target is approaching you from the right, and vice-versa if it's coming from the left. This is what the target's AOB will be when it crosses your nose or stern.
• Re-enage the TDC, "the blue button".
• Now your scope acts as a point and shoot device, ie. it automatically updates the correct AOB when you wheel it around, provided that neither you or the target changes course. If you need to change either speed or range inputs just disengage the TDC, change the input and then re-engage TDC. Just make sure you don't turn the scope or the AOB dial while the TDC is disengaged. Then again if you fire while the target is within 20-degrees of your nose the gyro-angle is usually small enough so that range doesn't really matter. You can also use the gyro-angle dial in the TDC to find the precise bearing where gyro-angle will be zero.

Source: Wazoo's FAST-90 tutorial

[I'm goin' down]

Originally Posted by Fincuan

I'll play a bit of Mythbusters first:

• The German TDC doesn't have a PK
  CONFIRMED, there is indeed no PK.
• The American TDC tracks even though the PK is off
  BUSTED, it does not track if the PK is switched off. That's the whole purpose of switching it off.

What the German TDC does is give you the correct lead-angle based on your speed, AOB and inputs. It does not actively track anything.

Doing all the 75 degree things just makes it all seem overly complicated, while it really isnt't. The technique mostly used with the German TDC is commonly called "Fast-90", and has been around at least as long as SH3, probably even longer. One way to do it:

• Get to a position 500 - 1000 meters off the target's track, at a 90 degree angle to the track.
• Point your scope to 0-bearing if your bow is pointing at the track, or 180 if it's your stern pointing at the track.
• Disengage the scope from the TDC, ie. "turn off" the TDC. This is the famous button with a light.
• Input target speed and approximate distance to the track at the moment of firing. Distance doesn't need to be all that precise if you fire as close to 0-gyro angle as possible.
• Turn AOB dial to 90 degrees port if target is approaching you from the right, and vice-versa if it's coming from the left. This is what the target's AOB will be when it crosses your nose or stern.
• Re-enage the TDC, "the blue button".
• Now your scope acts as a point and shoot device, ie. it automatically updates the correct AOB when you wheel it around, provided that neither you or the target changes course. If you need to change either speed or range inputs just disengage the TDC, change the input and then re-engage TDC. Just make sure you don't turn the scope or the AOB dial while the TDC is disengaged. Then again if you fire while the target is within 20-degrees of your nose the gyro-angle is usually small enough so that range doesn't really matter. You can also use the gyro-angle dial in the TDC to find the precise bearing where gyro-angle will be zero.

Source: Wazoo's FAST-90 tutorial

Okay! Easy enough. I looked at Wazoo's tutorial. I never played SH3. He talks about firing when not at a 90 degree angle to the target. I couldn't follow the explanation, as the mods and tools are different in SH3. Can that be done in ATO with OMEGU and KIUB? If so, can you give me basic instruction? In SH4 PTO, using manual targeting we can fire using a variety of gyro angles. I am not sure if that method is possible in ATO, but if I can fire at other than a 90 degree angle to the target, I assume you could.

[Fincuan]

You can find basic instructions for Fast-90 right there in my post. Just take some time and read it with thought, maybe even play out the situation ingame and experiment with things, and it should become clearer. Wasting torpedos is much cheaper in SH4 than irl.

Wazoo's tutorial can be followed through pretty much just like in SH3. Yes the UI is slightly different, actually a lot better imho, but what matters is the TDC looking and working exactly the same.

[I'm goin' down]

As I said, I understand your explanation of the fast 90. It was concise.

My question is that once I practice it I will want to try attacks at angles other than than 90 degrees. (Isn't that why we have the KIUB?) What is the procedure for those attacks using the TDC? Is it calculate Aob, Range and Speed with the KIUB. Turn off the TDC and enter the Aob, Range and Speed. Reactivate the scope. If so, where do you point the scope? I am not sure that procedure is correct.

I assume you can attack at angles as Wazoo's manual discusses it, but maybe I am wrong. I would rather not be confined to a fast 90 if there are alternatives.

[Fincuan]

The procedure is exactly the same in any other angle. What I probably didn't highlight enough is that when you initially point the scope to your nose and dial in the target's AOB at that bearing(ie. 90 left or right), you're not really pointing the scope at your nose but to a bearing that intersects the target's track at 90 degrees. In the above case, which is the simplest one, it just happens to be on your nose.

If you're be approaching the target's track at an angle, let's say 60 degrees, you just need to use some math to calculate the bearing at which your line of sight intersects the target's track at 90 degrees, turn your scope to that bearing and then continue setting up the TDC as before.

Example:
Our course is 250, target's course is 315

Bearing we need to point our scope at =
Target's course - 90 degrees - Our course = 315 - 90 - 250 = -25
-25 + 360 = 335

So we'd need to point our scope to bearing 335, then set-up the TDC. The explanation might not open up immediately, but if you draw it out or play it ingame, something which I can't do at the moment, it becomes clearer. Note that you need to use +90 degrees if target is coming from the right, and -90 if it's coming from the left.

[I'm goin' down]

Thanks. For some reason I cannot hit a target using the fast 90. I will keep working on it.

[I'm goin' down]

Short version -I was setting the Aob in the exact opposite direction.

The left side of the Aob dial says, "Bug Links." Translated this means bow of the ship left. When a target is approaching the bow of you your ship from starboard (i.e. it is moving from right to left), the Aob viewed from the target's bow is to its left (port). This means that the Aob dial on the UBoat, as viewed from the bow of the target, should be set to 90 degrees Bug Links (bow left.)

The right side of the Aob dial says, "Bug Recht." Translated this means bow of the ship right. When a target is approaching the bow of you your ship from the port (i.e. it is moving from left to right), the Aob viewed from the target's bow is to its right (starboard.) This means that the Aob dial on the UBoat, as viewed from the bow of the target, should be set to 90 degrees Bug Recht (bow right.)

For a captain such as myself who learned on an American sub this is counter intuitive. However, it now makes sense, plus it worked. I sank the submarine in the tutorial with four shots, all hits. The Aob reading was 80 degrees Bug Links (bow left) when the target crossed the wire at 10 degrees heading right to left at 7.5 kts. If I had fired when the target crossed the wire at 0 degrees, the Aob would have been 90 Bug Links (bow left.)

The above coupled with the explanation you and Wilke provided (Wilcke sent me PMs) were correct and much appreciated. My problem was that I could not read German. I used an German to English dictionary translation to figure it out.

Thanks for your help.