German TDC

[Bubblehead1980]

Originally Posted by derstosstrupp

My last post describes how to properly operate it but glad you’re sorted.

Yes, I have it figured out now. Got a hit no problem on a night surface attack. Thanks for your help.

Main issue was adjusting to the German TDC, it differences, combined with using metric system. Once you clarified things, was clear I was not operating TDC properly so final bearing at firing was usually off causing misses astern even though had correct speed.


Thanks again

[derstosstrupp]

Originally Posted by Bubblehead1980

Yes, I have it figured out now. Got a hit no problem on a night surface attack. Thanks for your help.

Main issue was adjusting to the German TDC, it differences, combined with using metric system. Once you clarified things, was clear I was not operating TDC properly so final bearing at firing was usually off causing misses astern even though had correct speed.


Thanks again

You are very welcome, glad to see you are enjoying the German side.

[Bubblehead1980]

Originally Posted by derstosstrupp

You are very welcome, glad to see you are enjoying the German side.

I am enjoying it, a lot. Different set of challenges but enjoying it now have TDC figured out. I love the german torpedoes, one torpedo will take out most ships, sometimes fire two on larger ships for good measure. Although, torpedo problems early in war...duds, running deep, premature explosions such as on US side as well, although they mostly are solved earlier to some degree in summer 1940, but issues persisted for german torpedoes until 1942. I've been researching the "torpedokrise". I knew they had problems, but was not aware of the details, not discussed much unlike the US torpedo failures.

I am currently in April 1940, supporting the Norway invasion...first attack, perfect TDC set up from 2300 meters on surface at night. Fired one G7e which was a dud, then another, which was a dud's (did not have any of the G7a's loaded, those are in reserve). Ship seemed alerted after second hit, but lowered speed slightly, refined AOB and solution, turned the TDC on, fired 3, which hit. Ship sunk ten minutes later, 5022 ton merchant-British.

Looking forward to next few patrols as things ramp up in summer fall 1940 in north atlantic. Hoping to introduced some AI subs into the mod for wolfpack ops as I did in TMO, at some point.

[Bubblehead1980]

Thanks for all the answers and help with German TDC. I am on my 4th patrol in Type VIIB started June 1 1940, now July 5 1940. Just fired my last torpedo after long running battle with large convoy in western approaches. Four large tankers sunk, had one tanker and three merchants down prior to finding convoy after 34 days on patrol. All manual TDC and Only three misses, one of which I suspect of running deep. Others were due to target speed changes during torpedo run.



Dark Waters/OM mod SH 4.
100 difficulty...map contacts and external cam off.

[derstosstrupp]

Originally Posted by Bubblehead1980

Thanks for all the answers and help with German TDC. I am on my 4th patrol in Type VIIB started June 1 1940, now July 5 1940. Just fired my last torpedo after long running battle with large convoy in western approaches. Four large tankers sunk, had one tanker and three merchants down prior to finding convoy after 34 days on patrol. All manual TDC and Only three misses, one of which I suspect of running deep. Others were due to target speed changes during torpedo run.



Dark Waters/OM mod SH 4.
100 difficulty...map contacts and external cam off.

Great to hear! Yeah once you get the German TDC down it can be devastating.

The biggest advantage imo is the direct connection to the optics which allows you to slew onto a new target or aim point and fire quickly without resending any new bearings - ideal for convoys.

I think the biggest advantage the US device had was the ability to use the PK to actually determine the data. Put rough estimates of AOB and speed in and a skilled operator could adjust these values accordingly based on comparing observed and generated ranges and bearings and arrive at a workable solution in something like 3-4 observations. Germans on the other hand, once dived, had to rely on the data they gathered while surfaced, using seaman’s eye to determine if any data may have changed. They got crazy close to compensate.

[Bubblehead1980]

Originally Posted by derstosstrupp

Great to hear! Yeah once you get the German TDC down it can be devastating.

The biggest advantage imo is the direct connection to the optics which allows you to slew onto a new target or aim point and fire quickly without resending any new bearings - ideal for convoys.

I think the biggest advantage the US device had was the ability to use the PK to actually determine the data. Put rough estimates of AOB and speed in and a skilled operator could adjust these values accordingly based on comparing observed and generated ranges and bearings and arrive at a workable solution in something like 3-4 observations. Germans on the other hand, once dived, had to rely on the data they gathered while surfaced, using seaman’s eye to determine if any data may have changed. They got crazy close to compensate.

I do like that aspect of the German TDC, can quickly switch targets within reason. I do miss the PK on US TDC though.


Yes, I tend to get quite close for my shots, but did that on US side as well. Typically 1000 yards submerged and 2000-2500 yards on surface depending.


I have the nights darkened so its possible to even get inside the convoys in Dark Waters mod now. Still perfecting it.


I know later in water it becomes difficult and often impossible to get in close and longer range shots are required. What is your advice on shooting a salvo or "fan" of torpedoes. I take it as select salvo, work solution on a "middle" target and set spread along the column, fire in salvo. How many degrees spread would suggest ? Ship lengths vary and but typically it looks like spacing of ships is usually 900 meters roughly.

[derstosstrupp]

Spreads are an interesting subject when it comes to games vs reality. There’s actually currently no U-boat simulation that gets the German spread correct. Whereas the Americans regarded their spread as covering generally the length of the target (which is what U-boat games also assume), the Germans thought of spreads as spreading torpedoes potentially multiple lengths of a target worth of dispersion. The Germans goal for a spread was to ensure one hit. If they intended to hit multiple torpedoes on one target they would fire what they called “multiple shots” (a “Mehrfachschuss”) simply just shifting the aim point and firing at different parts of the target.

In the game, if you look at the spread dial of the TDC, the game considers that the entire dispersion of the spread between the outermost torpedoes. In reality, that dial indicated the angle between each individual torpedo. So for instance if the spread dial read 3°, there would be 3° in between each individual torpedo, meaning that a spread of four would cover 9°. And given the German protocol of firing a spread only when the data is uncertain or the range is long, to hit one torpedo, that makes sense.

So now to translate that into game terms, if you want to mimic the German spread doctrine, don’t fire them if you plan on all eels hitting. In that instance, simply just shift fire on each subsequent shot. Only use spreads if you are very uncertain of your data or are at long range as somewhat of a Hail Mary.

And, spread them wide. To mimic how the real TDC worked and how the real gyro angle receiver set the gyro spindles, you can use your periscope to measure the angular length of what you are shooting at, and then multiply that by:
- 3 for a spread of 4
- 2 for a spread of 3
- 1 for a spread of 2
Set the result on the spread dial.

So like the example from before, if you can see that the target is about 3° wide so to speak in your periscope, and you want to shoot a spread of three, set 6° on the spread dial. It will send one torpedo where you aimed, one torpedo 3° left and one 3° right, greatly increasing the chance of one hit even on bad data.

As an aside, the German fire control system incorporated a spread angle calculator that took range, target length, and AOB into account to compute the spread angle that was transmitted to the gyro angle receiver. Prior to the model S3 this was a separate unit in the tower, and it was incorporated into the computer with the S3. The operator of the gyro angle receiver in the bow room matched the spread angle by hand (matched the pointers) and that set the gyros in the eels to the correct ratios. The spread was fired automatically by holding the firing lever down until the last eel left, at an interval of 2.5 seconds between eels, different than the US which fired each individually.

[Bubblehead1980]

Originally Posted by derstosstrupp

Spreads are an interesting subject when it comes to games vs reality. There’s actually currently no U-boat simulation that gets the German spread correct. Whereas the Americans regarded their spread as covering generally the length of the target (which is what U-boat games also assume), the Germans thought of spreads as spreading torpedoes potentially multiple lengths of a target worth of dispersion. The Germans goal for a spread was to ensure one hit. If they intended to hit multiple torpedoes on one target they would fire what they called “multiple shots” (a “Mehrfachschuss”) simply just shifting the aim point and firing at different parts of the target.

In the game, if you look at the spread dial of the TDC, the game considers that the entire dispersion of the spread between the outermost torpedoes. In reality, that dial indicated the angle between each individual torpedo. So for instance if the spread dial read 3°, there would be 3° in between each individual torpedo, meaning that a spread of four would cover 9°. And given the German protocol of firing a spread only when the data is uncertain or the range is long, to hit one torpedo, that makes sense.

So now to translate that into game terms, if you want to mimic the German spread doctrine, don’t fire them if you plan on all eels hitting. In that instance, simply just shift fire on each subsequent shot. Only use spreads if you are very uncertain of your data or are at long range as somewhat of a Hail Mary.

And, spread them wide. To mimic how the real TDC worked and how the real gyro angle receiver set the gyro spindles, you can use your periscope to measure the angular length of what you are shooting at, and then multiply that by:
- 3 for a spread of 4
- 2 for a spread of 3
- 1 for a spread of 2
Set the result on the spread dial.

So like the example from before, if you can see that the target is about 3° wide so to speak in your periscope, and you want to shoot a spread of three, set 6° on the spread dial. It will send one torpedo where you aimed, one torpedo 3° left and one 3° right, greatly increasing the chance of one hit even on bad data.

As an aside, the German fire control system incorporated a spread angle calculator that took range, target length, and AOB into account to compute the spread angle that was transmitted to the gyro angle receiver. Prior to the model S3 this was a separate unit in the tower, and it was incorporated into the computer with the S3. The operator of the gyro angle receiver in the bow room matched the spread angle by hand (matched the pointers) and that set the gyros in the eels to the correct ratios. The spread was fired automatically by holding the firing lever down until the last eel left, at an interval of 2.5 seconds between eels, different than the US which fired each individually.

Thanks for the info. Appreciate all your answers

Yes, I use the method of pointing where want torpedo (Constant Bearing I think its called on the US side) and using individual bearings for each torpedo. However, for long range shots this is not the best method. US TDC has the spread knob and adjust right up to firing but German TDC in the game can only use the spread knob when Salvo is selected and when the TDC input mod is off, so have to preset the spread.


However, single bearing method is not always best for longer range shots, which sure will have to do at some point...later in war for example or in a hail mary as mentioned. I tried once off Norway against Repulse Battlecruiser making high speed. I fired a spread of four from 4800 meters (close as I could get) with a 10 degree spread for a "fan" and got a hit, only her escorts saved her, preventing follow up. Love having the salvo option, figure as mentioned, later in war will come in handy when have to fire from longer ranges at convoys. I figure in a hail mary situation, aim for center and fire with a spread.


I successfully did this (Following real life example of USS Jack's attack on the Take Ichi Convoy in April 1944) with in TMO mod. With the 3D TDC and Radar (actual working surface radar linked to TDC) attacked the convoy I added representing the Take Ichi Convoy. 14 Transports and 13 escorts...screen was so heavy, much like the real USS Jack, could not get inside on surface at night for attack, nor inside for a decent submerged shot.

So like the Jack, I used the radar to get a bearing on ship in middle of convoy from about 7800 yards, set torpedoes to low power for long range, and fired six bow and then four stern. I used spread from 5-15 degrees....I got six out of ten hits...sunk four transports and a escort.


I've replicated it a few times. Obviously the U Boat's do not have the SJ radar capability of fleetboat but was just trying to figure out spread for average convoy . I've noticed nearly all spacing is 900 meters between ships. I have a idea but though I would check. Thanks again for th einfo.

[derstosstrupp]

The other thing to keep in mind is, by the time it becomes necessary to fire these types of blind shots into convoys, it is late enough where you have FAT and LUT technology, and so you may not necessarily be firing spreads. You could fire a number of those types of torpedoes into the convoy to increase your chances of a hit.

[Bubblehead1980]

Originally Posted by derstosstrupp

The other thing to keep in mind is, by the time it becomes necessary to fire these types of blind shots into convoys, it is late enough where you have FAT and LUT technology, and so you may not necessarily be firing spreads. You could fire a number of those types of torpedoes into the convoy to increase your chances of a hit.

Ah yes, I will have questions when that time comes lol. Never used FAT or LUT in the sim.

[John Pancoast]

One time I was testing a FAT and the search loop was perfect to hit a large tanker in the middle of a convoy........................except it would turn 180 degrees for it's next loop literally a yard or two from the tanker!?!?
Hilarious watching in external view as it's search grid followed the tanker's course perfectly, loop after loop only to have the torpedo turn away from impact at the last second time and time again.
It finally ran out of energy and sank without hitting anything.

[Bubblehead1980]

Originally Posted by John Pancoast

One time I was testing a FAT and the search loop was perfect to hit a large tanker in the middle of a convoy........................except it would turn 180 degrees for it's next loop literally a yard or two from the tanker!?!?
Hilarious watching in external view as it's search grid followed the tanker's course perfectly, loop after loop only to have the torpedo turn away from impact at the last second time and time again.
It finally ran out of energy and sank without hitting anything.

[FUBAR295]

Originally Posted by John Pancoast

One time I was testing a FAT and the search loop was perfect to hit a large tanker in the middle of a convoy........................except it would turn 180 degrees for it's next loop literally a yard or two from the tanker!?!?
Hilarious watching in external view as it's search grid followed the tanker's course perfectly, loop after loop only to have the torpedo turn away from impact at the last second time and time again.
It finally ran out of energy and sank without hitting anything.

Pretty funny but a grrrrr moment anyway.

Thanks for the chuckle.