TDCs in U.S. subs are driving me Nuts!

[Benzin1973]

Maybe i managed to "burn" how the German TDC & torpedos work in SH3 so well into my brain, that it refuses to understand how it works on U.S. Subs in SH4, because for the life of me i just dont get it.

Ibe watched countless videos, read several tutorials, spend a few hours practising, even on the tutorial mission firing @ 900 meters i still miss about half the time.

In SH3, i have gotten the hang of it so well, that i know that firing at anything that is below 2500 meters, is pretty much a sure shot. But here, i cant seem to hit anything consistently.

Videos & tutorials have contradictory information, some say take the AOB once, some say twice, some say just set the AOB to match true target course, some say dont bother with the PK, some say its impossible without it, etc.

I would really appreciate some help. But instead of a method that i just "do", i would like to understand HOW the US TDC works, so i can use diferent methods depending on the situation, just like i do on SH3.

¿Does the TDC update the AOB automatically according to bearing, like the german one does?

If i click the "send AOB to TDC" button once, the left dials change to a position, i click again and they change again! ¿so do i click once or twice?

¿Is the AOB i enter on the disk on the upper right related/linked to my current bearing on the periscope/uzo? in other words, does TDC treat that AOB for a target bearing at say 050 but would be diferent if i was looking at 120 (like in SH3)?

I understand that unlike German TDCs, in this ones i have to send the target bearing on my periscope by sending the range (right?), after i do so, do i have to also enter the current AOB, or does the TDC understands target has moved and correct accordingly?

¿Are the outer numbers on the upper disk of the left side dials the true target bearing? and if so, why does it change when i turn on the "PK"? target has NOT changed its course, and i have NOT entered a new AOB, so why does it change?

I dont use the automatic "calculate speed" feature (ibe allways used 3.15min. system or nomograph), but when i have tried to use it, i take a range & position reading, enter current AOB, wait a while then take another, and request speed estimation. Half the time crew says "they dont have enough data" what gives?

All the "PK" does, is to "predict" the targets movement, and update the solution accordingly, right? so how come it messes up my solution almost every time i turn it on?

When i do manage to aim properly:
Targets dept is (e.g.) 6.8 meters. So i set two torps to run at 7m dept. So they will explode under target (and make sure magnetic pistols are on of course). Yet every single time i see them pass under the ship without detonating! Is this a (major) game bug or im i missing something?

On a side note, i am well used to getting target true bearing and speed from plotting before i even get close to it. But while doing this on SH3 about trippled my accuracy, here it doesnt seem to make much diference compared to just using guesstimates and TDC helpers, so i must be doing something wrong. But i cant figure out what.

If anyone can point me in the right direction i would really appreciate it.

EDIT:
Sorry forgot to mention, my mod list is:
GFO 1.1
Red eye fix (doesnt work btw)
metric nomograph
3000 bearing overlay
large dials.

[Hitman]

Uh, strange that after watching the tutorial nothing works for you ...

Anyway. The main difference, the only you really need to know to get your head around how the US TDC works is that, unlike the german one, the american unit auto-updates based on your latest inputs.

Think of it as an old winding wristwatch. To set it on the correct time, you push the winding crown and then you set the needles to the proper position, then push the corwn again and it starts moving. It will then show the time, but if you see that it is lagging or going too quick, you push the crown out and adjust it again.

The US TDC works almost the same.

You make the basic initial inputs (Range, AOB, speed) and "push the crown" by clicking the position keeper. Up from then, you can update any of the inputs manually, and it is like fine adjusting the time in your wristwatch.

The torpedoes will always be aimed at what the TDC displays as current target position.

The advantage: You have a fantastic tool that will allow you attacks without even seeing the target or when you have a good solution (submerged or at night using the radar) and you can double check how good the solution is by monitoring that the bearing/AOB/distance you see on the scope or radar matches the one displayed by the TDC.

The disadvantage: It is less spontaneous for quick changes when the target surprises you (Sudden zig-zagging) or when attacking multiple targets (In game limitation, as the real unit could keep track of more than one target IIRC). But the good news is that some clever guys around have developed methods to help with that, and practice makes masters

[Rockin Robbins]

Let me take a stab at specifically answering some questions you asked and then give you a conceptual overview of the American TDC.

Originally Posted by Benzin1973

Does the TDC update the AOB automatically according to bearing, like the german one does?

No. Neither did the German one. Only the game German TDC automatically does such a thing. In reality, the person reading the vernier called out the bearing to the TDC operator in both American and German boats. The TDC in Silent Hunter 4 works authentically in that regard. The TDC in
Silent Hunter 3 does not.

Originally Posted by Benzin1973

If i click the "send AOB to TDC" button once, the left dials change to a position, i click again and they change again! ¿so do i click once or twice?

You've watched my videos and they prove that you MUST CLICK TWICE! You'll only see that in my videos, along with some other wrinkles that escape notice elsewhere. But facts are not subject to a vote or the prevalent opinion. They are and we must comply or fail. You must also click twice when sending the range/bearing for the same reason as proven in my videos.

Originally Posted by Benzin1973

Is the AOB i enter on the disk on the upper right related/linked to my current bearing on the periscope/uzo? in other words, does TDC treat that AOB for a target bearing at say 050 but would be diferent if i was looking at 120 (like in SH3)?

No. Think about that an angle on the bow is and you'll see that's ludicrous. The angle on the bow is your bearing in German nomenclature (starboard/port 0-180º) from the target. It's really easy to visualize yourself on the target saying "Submarine! Bearing starboard 86º!" It might be harder to realize that no matter what direction that sub is facing his bearing is still 86º starboard. Isn't it? So his AoB is unrelated to your submarine's periscope bearing, isn't it!

Originally Posted by Benzin1973

I understand that unlike German TDCs, in this ones i have to send the target bearing on my periscope by sending the range (right?), after i do so, do i have to also enter the current AOB, or does the TDC understands target has moved and correct accordingly?

This is a defect in Silent Hunter 4. There is no way to send a periscope or TDC bearing to the TDC without also sending a range! And you must correct AoB manually there unless you have engaged the position keeper.

Originally Posted by Benzin1973

Are the outer numbers on the upper disk of the left side dials the true target bearing? and if so, why does it change when i turn on the "PK"? target has NOT changed its course, and i have NOT entered a new AOB, so why does it change?

No, the outer numbers on the upper disk indicate the course of the target. When you engage the PK the TDC generates an artificial target which moves at the speed and on the course you tell the TDC the terget is moving. If your input numbers are correct and the position, course and speed of the artificial target and the real target are identical, the torpedoes are updated continuously as to gyro angle. You can shoot at any time and hit your target. You don't check this with dials. You check it with the little understood but crucial attack map.

Originally Posted by Benzin1973

I dont use the automatic "calculate speed" feature (ibe allways used 3.15min. system or nomograph), but when i have tried to use it, i take a range & position reading, enter current AOB, wait a while then take another, and request speed estimation. Half the time crew says "they dont have enough data" what gives?

Your sightings must not only be accurate but they must be more than a certain number of seconds apart. Then it calculates the speed wrongly and you miss. Why? Because stadimeter readings are imprecise and overly finicky. Unless you are within 1500 yards forget using that method. If you are within 1500 yards you don't have the time. Insert appropriate curse words here.

Originally Posted by Benzin1973

All the "PK" does, is to "predict" the targets movement, and update the solution accordingly, right? so how come it messes up my solution almost every time i turn it on?

Because it predicts the movement of the target based on the information you give it. What order you provide that information is crucial. No, you won't find that anywhere but in my videos and here and in the Sub Skippers' Bag of Tricks thread. Also, just as the real submarines tested the validity of their solution before firing, so must you. That is done on the attack map, a feature so poorly understood that RFB removed all access to it.

Originally Posted by Benzin1973

When i do manage to aim properly:
Targets dept is (e.g.) 6.8 meters. So i set two torps to run at 7m dept. So they will explode under target (and make sure magnetic pistols are on of course). Yet every single time i see them pass under the ship without detonating! Is this a (major) game bug or im i missing something?

American torpedoes were copies of captured German ones. And in a credit to German engineering the American copies were so good that they copied the defects perfectly! The torpedoes routinely ran deeper than set by at least 15 feet. Unlike the German military, American brass knew everything and anything that went wrong in the field was the fault of the front line command. The torpedoes were perfect because the brass said they were. Sub skippers who called attention to the faulty torpedoes were crawling on some god forsaken beach landing the next week. Wimps! It was a long time before the American torpedoes were fixed. What the Germans fixed in a month took three years here. Yeah, it's a bug, but it's a bug accurately reflected where it belongs: the American military command structure not trusting the man getting shot at.

Looks like I need to work up a video showing how the American TDC works and why it was really superior to the German TDC. While the American TDC could easily execute a German style attack to perfection (even in the game, despite the problems with the game TDC vs the real one), the German TDC could not even begin to execute an American style attack.

The American TDC was so good that if you had the numbers right, you could actually dive the sub to 100' (99' in the game, another egregious bug), change course and speed, then shoot at any time without ever regaining sight of the target. You would get hits. I don't need to say what that means for your evasion success! Many Germans died because they didn't have this capability.

Time to make a video. No time prediction. As usual I'm pretty busy but this is a project I've been wanting to do for years.

[Rockin Robbins]

Position keeper thought illumination:

Let's think an an analogous way about what happens in the TDC. We'll visualize both what the real target and the artificial target, the object the TDC actually shoots at, will do in a situation.

Let's say our initial TDC settings are speed 0, bearing 0, distance 0, course 0. Usually that will not be true but you have to start somewhere.

You have a target moving 8 knots, course 45º. Let's start.

Up scope, engage PK. Why engage PK first? Because you'll forget to if you don't! And it allows us to visualize what is going on in the twisted mind of the American TDC. Bearing, MARK! Range, MARK! Press send bearing/range button twice and the TDC now knows the position of the target, doesn't it? But it's moving 0 knots on course 0. As soon as you enter that position it's wrong!

Now you ask your charting crew about the target's speed. They say 10 knots, so you set speed to 10 knots and hit that send button twice because if you do it the same way all the time you'll not do it wrong. Right? In the twisted mind of the TDC your artificial target has begun to move from its initial position straight North at 10 knots!

Finally you estimate the AoB or get target course from your plotting crew and enter that 45º course into your TDC. Your artificial target now starts moving in the correct direction. After not moving at all in the pause between your position input and your speed input. After moving 10 knots in the wrong direction after you input the speed. So it's north and behind the real target, but moving at the same course and speed.

You've entered all the information into the TDC that you need, you've done it accurately--good job by the way. If you shoot, will you hit? No, you are going to miss by a mile because you haven't looked deeply into the twisted heart of the TDC and understood how it works!

Let's do it right by understanding that the order we do our business isn't just a matter of Rockin Robbins' opinion, it's the difference between boom and wahhhhhh!

When you first acquire your target use your radar to take two positions on the nav map three minutes apart. Measure the distance between those two positions in yards. The number of hundred yards the target runs in three minutes is its speed in knots. Enter that number FIRST into your TDC. Chances are that won't change. And turn on the PK first, just as before for the same reason.

Then connect those positions and extend a line in the same direction as the target's travel. This is the target track. Measure its course. There's a way to enter than semi-directly into the TDC. Do it now and press send twice. That's another parameter that might not change.

Now the TDC has a pip moving at the course and speed of your target but it's at the wrong location. As soon as you nail the location you have everything instantly correct at the same time! Don't you?

NOW, when you use your stadimeter to find bearing and distance, stab the button twice, that pip, which is already moving at the correct course and speed is instantly put where it belongs. And it instantly begins moving at the correct course and speed, doesn't it?

Now go to the attack map. You'll see the radar position of the target and the artificial target generated by the TDC. Are they on top of one another? See the torpedo run time? Do they STAY on top of each other for that period of time? Then you will hit your target. Is the pip moving slightly faster than the real target? Input a lower speed. Click twice and check the attack map.

Is it moving on a diverging course? Change the course slightly and click twice. Check the attack map.

Is it shadowing the target but just not at the correct location? Take another periscope bearing/range observation. Check the attack map.

When you're happy open torpedo doors and shoot whenever it blows your skirt up. Boom! Baby! Damn. Now I've spoiled the end of my video and no one will watch it.......

[Rockin Robbins]

So here I am in broad daylight setting up a 12 knot target, doing an end around, getting five miles ahead of him on the track, 1000 yards off, submerge to radar depth to keep an eye on him, video going great and he......slows to 1 knot. Never saw that before in ANY target in broad daylight. End of video. I'll try again another day!

@Benzin1973
I've got a little used to understand how this works in SH4.
Here one must also admit that this is still represented very simplified and simulated however.
You'll figure it out for you - but it's like giving a baby pacifier ... it just does.

Good luck commander.

[Hitman]

Neither did the German one. Only the game German TDC automatically does such a thing. In reality, the person reading the vernier called out the bearing to the TDC operator in both American and German boats. The TDC in Silent Hunter 4 works authentically in that regard. The TDC in
Silent Hunter 3 does not.

Sorry I think that is not correct. The german TDC locked the triangle in the "Lage folgend" mode and auto-updated it based on the bearing of the optical aiming device (Periscope or UZO) as is represented in the game. The difference with real life is that it updated much slower than in the game (instantaneous in our game) because the whole cascade of pinions and springs had to update.

Oh and it also auto-corrected for changes in uboat course, which our virtual TDC unfortunately does not.

It was by far a less complex piece than the US unit, but it served well in Uboats where the captain had to do many more things than the US one, had less info available (Radar) and spontaneous shooting at different bearings was crucial.

[Rockin Robbins]

I can't remember who told me--it was a prominent SH3 player--that the periscope did not automatically update the TDC and the bearings were called out and manually entered. Shouldn't be all that difficult to find out what's the real facts. Basically he called me out when I stated that the German periscope automatically updates TDC on the real sub and I deferred to his greater expertise.

[Benzin1973]

Thank you guys for your great explanations!

After carefully reading your answers, I think i now have a clearer understanding of the diferences of the US TDC vs German TDC.

Regarding the issue of the TDC (not) updating the AOB as target approaches, if i understand correctly, it will update AOB (as well as bearing and range) as long as the PK is on. But if the PK is off, then i have to do this myself. right?

For example:
Suppose im standing still, 90º off to to port ahead on targets path (standard perpendicular approach). I take some readings when target is say 2000m out, his AOB is e.g.30º. But then target continues its "walk" down the line towards me, when he is 1200m out, his AOB is no longer 30º, now its say 75º. In SH3 i dint have to enter a new AOB of 75º (provided target dint change course!), as my presicope followed the target, not only did the bearing get updated, but the TDC automatically upgraded the AOB. But here i do have to take the AOB again and enter it into the TDC. Exception being, if the PK is on. In this case the TDC will update AOB, range & bearing automatically.
Did i understand correctly?

Another thing that i probably dint do (not all the time at least) on my last tests, is to send the bearing (and range) just prior to firing. If the PK were on, it probably wouldnt have been much of a problem, but it was probably off. And i bet i did forget to do that a few times.

It seems that my main problem is getting used to the idea that unless the PK is on (and perfect data has been entered to it), my persiscope does NOT automatically send the bearing to the TDC, and that my TDC does NOT automatically update the AOB.
Sort of like "unlearning" it then learning it again!

I really appreciate your help guys, I will continue to practise some more and report back here.

[Benzin1973]

Forgot to mention:
@ Rocking Robbins: You are RockingRobbins13 on YT right?
Suscribed, and Looking forward to your new video!

[Rockin Robbins]

Originally Posted by Benzin1973

Thank you guys for your great explanations!

After carefully reading your answers, I think i now have a clearer understanding of the diferences of the US TDC vs German TDC.

Regarding the issue of the TDC (not) updating the AOB as target approaches, if i understand correctly, it will update AOB (as well as bearing and range) as long as the PK is on. But if the PK is off, then i have to do this myself. right?

For example:
Suppose im standing still, 90º off to to port ahead on targets path (standard perpendicular approach). I take some readings when target is say 2000m out, his AOB is e.g.30º. But then target continues its "walk" down the line towards me, when he is 1200m out, his AOB is no longer 30º, now its say 75º. In SH3 i dint have to enter a new AOB of 75º (provided target dint change course!), as my presicope followed the target, not only did the bearing get updated, but the TDC automatically upgraded the AOB. But here i do have to take the AOB again and enter it into the TDC. Exception being, if the PK is on. In this case the TDC will update AOB, range & bearing automatically.
Did i understand correctly?

By jove, you've got it exactly! And that means that if you want to do a U-boat style attack, first you set the TDC, THEN you maneuver your boat into position along the track so the hapless target will put himself at the settings you've preloaded into the TDC. As he crosses the wire you aim each shot for a specific point on his soon to be carcass!

Originally Posted by Benzin1973

Another thing that i probably dint do (not all the time at least) on my last tests, is to send the bearing (and range) just prior to firing. If the PK were on, it probably wouldnt have been much of a problem, but it was probably off. And i bet i did forget to do that a few times.

It seems that my main problem is getting used to the idea that unless the PK is on (and perfect data has been entered to it), my persiscope does NOT automatically send the bearing to the TDC, and that my TDC does NOT automatically update the AOB.
Sort of like "unlearning" it then learning it again!

I really appreciate your help guys, I will continue to practise some more and report back here.

Yes, it does the same thing as the German TDC but in such a different way that all your automatic actions for the U-Boat are now maddeningly changed. It would be better to start with total ignorance than to know the German TDC really well!

But not really. Boat handling is very similar. Strategy is similar. The killer advantage of the American boat is radar. With it you can do 2/3 of the TDC setting before you've ever laid eyes on the enemy. When he's in sight the only thing you have to do is verify and get that stadimeter reading if you're using the PK.

If not, then you don't even have to do that! And yes, I am Rockinrobbins13 on You Tube. Thanks for being such a quick study. It's much harder to unlearn something before you can learn something else. But after you learn the American TDC you'll find that your U-boat experience is invaluable.

It's a lot like when a real pilot decides to fly radio control airplanes. Initially, his full size flying experience is actually a hindrance because he's not in the plane! He is standing on the ground in a completely different frame of reference than he is used to. He has no instruments. So he crashes more than a complete newbie would. At first.

Once he actually can fly the beast, suddenly his full size experience makes him a much better RC pilot! Once the perspective thing is beaten, planes are planes and he's an expert!

So with you. Have fun!

[Benzin1973]

Thanks!
Spent most of the night playing and (trying to) practise, but before that i chose to install RSRD, and after several hours (real world hours, not ingame hours), and two visits to refuel, all that i found was a *single* merchant.
It Seems its easier to find a merchant ship in the mohave dessert than on RSRD
The only thing i found plenty of, was planes. And i admit i had a very hard time shooting torpedos at them.

Anyway, luckily i had a saved game of when i first detected that merchant, i must have loaded it about 50 times! and i tried sinking it every way imaginable, from far away, up close, etc. And i would say my success rate improved to about 90%. that poor merchant died about 45 times!

I guess something just "clicked" in my brain (thanks to your explanations), and i finally got it.

Now to remove RSRD and play some vanilla + some fixes/improvement mods i got (GFO + Real Env + Nomograph + bearing overlay + Improved dials). And hopefully get more practise instead of staring at empty sea!

[Benzin1973]

OMG! Warship, 19knots, just shy of 3000 meters out. I dint think i would hit it!
Fired two fishes...
And i dint hit it!

Seriously though, i would have hit it, but even tho i set the dept at ONE lowsy meter (cant go shallower than that), both fish passed under it without detonating.

Point is, my aiming was correct. It seems i got it.
Thanks a lot guys!

[Rockin Robbins]

Especially early in the war I set the torpedoes to run as shallow as I can set them. You would change that with capital ships, but on them I'd set 10' less than the keel depth. That way if the torp runs deep you'll still get a boom.

Yes, early in the war RSRD can make it very difficult to find targets. That is because early in the war subs were sent to empty hunting areas. Then when the sub came back empty it was a simple matter to remove the skipper as not being aggressive enough. Then you send the sub out again to an empty hole in the water........

Took the American command structure altogether too long to figure out how to do a war.

[Hitman]

Originally Posted by Rockin Robbins

I can't remember who told me--it was a prominent SH3 player--that the periscope did not automatically update the TDC and the bearings were called out and manually entered. Shouldn't be all that difficult to find out what's the real facts. Basically he called me out when I stated that the German periscope automatically updates TDC on the real sub and I deferred to his greater expertise.

I think he was wrong, but in any case for the purposes of explaining to Benzin what he wanted to know we are comparing SH3 TDC vs. SH4 TDC
so it's no big deal what they had in real life, what we have in the games is what matters to sink virtual tonnage