Depth Charges?

[jericho791]

So I have a question about depth charges.


Last night I was playing SH4 (FotRS) Co-op with my sons, and I noticed that every time a DD managed to DC me, they did so with pinpoint accuracy. Didn't matter that I was changing depth and course and speed. The DC's would rain down right on top of me and explode at the exact depth that I was at in that moment. On one occasion I was sitting at 320 feet all ahead slow, and the DD dropped charges on me, and they came down and exploded at exactly 320 feet.


So my question is, how is the DC depth setting logic rendered in SH4?



Back in SH2 days, when playing in conjunction with Destroyer Command, the destroyers had to set the depth that the charges would explode, just like they had to do in real life. If they didn't set them right, the charges would explode above you, or below you depending on their setting.



Do the charges in SH4 have depth settings, or do they just explode at a depth based on the depth of your submarine?

[KaleunMarco]

Originally Posted by jericho791

So I have a question about depth charges.


Last night I was playing SH4 (FotRS) Co-op with my sons, and I noticed that every time a DD managed to DC me, they did so with pinpoint accuracy. Didn't matter that I was changing depth and course and speed. The DC's would rain down right on top of me and explode at the exact depth that I was at in that moment. On one occasion I was sitting at 320 feet all ahead slow, and the DD dropped charges on me, and they came down and exploded at exactly 320 feet.


So my question is, how is the DC depth setting logic rendered in SH4?



Back in SH2 days, when playing in conjunction with Destroyer Command, the destroyers had to set the depth that the charges would explode, just like they had to do in real life. If they didn't set them right, the charges would explode above you, or below you depending on their setting.



Do the charges in SH4 have depth settings, or do they just explode at a depth based on the depth of your submarine?

your example does make it seem as if the sim is using 20th hydrophone/sonar technology...of which you are very aware.

in SH4, the enemy detects you based on sound and then decides at what depth to set their DC. the DC themselves have a plus/minus factor to apply, similar to the torpedo defect percentages. it could be that in the instance you describe above, all of the variables came up sevens for the IJN and snake eyes for you and your valiant crew.

if you want to get into the variables, d/l skwas' S3ditor and check out \library\DepthCharges_IJN.sim and .zon.
these two files will allow you to see behind the curtain. you, as a former sonar tech, will understand more of the subtleties than the regular player.

one other suggestion...you didn't mention which boat you were driving. you may want to also use the S3ditor and check out the submerged RPM for your boat in Submarines\yourboattype\yourboattype.SIM. look in the Electric Propulsion section. within SH4, your boat's underwater sound profile is directly related to its RPM. if you feel like it, you can appeal to one of your classmates in BuShips to let you adapt your boat.

good luck and good hunting!

[Bubblehead1980]

I have modified the depth charges in TMO(will release soon). I believe their accuracy has to do with the depth precision setting in the depth charges .sim file. Not sure what FOTRS stock etc has it set to but in TMO it is set to 15 meters. Based on my testing, I assume that that basically means they will set them to explode at a depth within 15 meters of the depth they believe you are at based on their sonar information. In testing I upped it to 20 etc and they were not always as close. I also have two mods, one for early war charges and later war charges. Changed the hit point values to reflect the heavier late war charge but also lowered them both from their original values because they were set quite high. Now with the changes depth charges(as they did in real life) don't kill you unless score a direct hit which is unlikely, instead they beat your sub up, destroy key systems such as trim pump etc until you have to surface to survive, until the escort shoots you on surface.

[Col7777]

Funny this came up, I have recently downloaded the Mediterranean Campaign, and during one of the missions I got detected so I went deep, rigged for Silent Running and headed away from the convoy.

The DD's came hunting, I was creeping away at 4 knots at 160ft. As one of them came straight for me I deployed decoys, that seemed to work, it went over me then dropped DC's a fair distance away.
I just kept moving away, the others also came but concentrated on an area a good way behind me.
I was on the free cam watching them DC an area I wasn't in, there were in the end 7 DD's plus at one stage an aircraft also bombed an area a good way from me.
The DD's eventually gave up and left the area, I surfaced when it was safe I never scored a hit but in a way I felt I did for evading all those hunters and got the crew home safe.

This leads me to a question, this was the first time I deployed decoys, so how far do they go to lead a DD to ignore you, how do they work?
I've seen them in modern sub movies but this is WW2 and in the sim they worked in this case anyway.

Edited to add:
I was in the Porpoise sub and the Japanese DD's seemed to be a few various types.

Col.

[KaleunMarco]

Originally Posted by Col7777

Funny this came up, I have recently downloaded the Mediterranean Campaign, and during one of the missions I got detected so I went deep, rigged for Silent Running and headed away from the convoy.

The DD's came hunting, I was creeping away at 4 knots at 160ft. As one of them came straight for me I deployed decoys, that seemed to work, it went over me then dropped DC's a fair distance away.
I just kept moving away, the others also came but concentrated on an area a good way behind me.
I was on the free cam watching them DC an area I wasn't in, there were in the end 7 DD's plus at one stage an aircraft also bombed an area a good way from me.
The DD's eventually gave up and left the area, I surfaced when it was safe I never scored a hit but in a way I felt I did for evading all those hunters and got the crew home safe.

This leads me to a question, this was the first time I deployed decoys, so how far do they go to lead a DD to ignore you, how do they work?
I've seen them in modern sub movies but this is WW2 and in the sim they worked in this case anyway.

Edited to add:
I was in the Porpoise sub and the Japanese DD's seemed to be a few various types.

Col.

in SH4, a decoy will create a noise field over a given area at whatever depth you released it for a specific length of time. early in the war the area is smaller and the duration is less than later in the war.

in your story above, you did exactly what you are supposed to do: release a decoy, go a bit deeper, change course 90 degrees, and, of course, slow down.

[Sniper297]

I'd have to hunt through SINK 'EM ALL to find the exact year, but best I recall the "Alka-Seltzer" bubble decoy (copied from the German "pillenwerfer") wasn't available until 1943 or 1944. Stock game has them available at the beginning, although you only get 10 per patrol and they only last 10 minutes. I made a hack for that;

https://www.subsim.com/radioroom/dow...o=file&id=5186

Which makes it easier, not harder. Although the game itself has oversimplified programming that makes everything ridiculously easy or ridiculously hard, the AI seems to call the Psychic Friends Network and get a crystal ball reading sometimes, at other times they're completely clueless.

I was an Aviation ASW Tech in a heavy helicopter antisubmarine squadron 40 years ago, so the only real sonar I'm familiar with was the AN/AQS-13 Alpha in the Sikorsky Sea King helicopter.



Pic of the dip sonar being retracted, built in bathythermograph and could be adjusted from 40 feet to 450 feet deep to check between layers. A lot more powerful and sophisticated than anything in WWII, and omnidirectional so there was no need to sweep or focus on a target. I can tell you that the stock game oversimplifies thermal layers, they're treated like a flat plane at a constant depth. In the \Data\Cfg\Sim.cfg file is the sensitivities for the AI;

[Hydrophone]
Detection time=1 ;[s]
Sensitivity=0.15 ;(0..1)
Height factor=0 ;[m]
Waves factor=1.0 ;[>=0]
Speed factor=15 ;[kt]
Noise factor=1.0 ;[>=0]
Thermal Layer Signal Attenuation=3.0 ;[>0], 1 means no signal reduction, 3 equals signal reduction to 33%

[Sonar]
Detection time=5 ;[s]
Sensitivity=0.1 ;(0..1)
Waves factor=1.0 ;[>=0]
Speed factor=20 ;[kt]
Enemy surface factor=200 ;[m2]
Lose time=30 ;[s]
Thermal Layer Signal Attenuation=5.0 ;[>0], 1 means no signal reduction, 5 equals signal reduction to 20%

In the stock game if you were at 320 feet, even running at flank speed they wouldn't be able to hear you let alone get an echo, because the stock game settings are beyond crazy. I would guess if you look at that file in FOTRS you'll find they went overboard in the other direction, possibly some middle setting would work better - my personal hacking goals are challenging but not impossible.

In real life thermal layers are varying strength and depth, no way I know of to simulate that in this game.

Don't recall trying FOTRS, but all the other super mods I've tried seem to focus on making everything more difficult. If the arcade style "GAME OVER!!" happens too frequently, I'd suggest editing the files to make the depth charges/AI sonar a little less accurate and/or less damaging.

[Macgregor the Hammer]

Originally Posted by Sniper297

I'd have to hunt through SINK 'EM ALL to find the exact year, but best I recall the "Alka-Seltzer" bubble decoy (copied from the German "pillenwerfer") wasn't available until 1943 or 1944. Stock game has them available at the beginning, although you only get 10 per patrol and they only last 10 minutes. I made a hack for that;

https://www.subsim.com/radioroom/dow...o=file&id=5186

Which makes it easier, not harder. Although the game itself has oversimplified programming that makes everything ridiculously easy or ridiculously hard, the AI seems to call the Psychic Friends Network and get a crystal ball reading sometimes, at other times they're completely clueless.

I was an Aviation ASW Tech in a heavy helicopter antisubmarine squadron 40 years ago, so the only real sonar I'm familiar with was the AN/AQS-13 Alpha in the Sikorsky Sea King helicopter.



Pic of the dip sonar being retracted, built in bathythermograph and could be adjusted from 40 feet to 450 feet deep to check between layers. A lot more powerful and sophisticated than anything in WWII, and omnidirectional so there was no need to sweep or focus on a target. I can tell you that the stock game oversimplifies thermal layers, they're treated like a flat plane at a constant depth. In the \Data\Cfg\Sim.cfg file is the sensitivities for the AI;

[Hydrophone]
Detection time=1 ;[s]
Sensitivity=0.15 ;(0..1)
Height factor=0 ;[m]
Waves factor=1.0 ;[>=0]
Speed factor=15 ;[kt]
Noise factor=1.0 ;[>=0]
Thermal Layer Signal Attenuation=3.0 ;[>0], 1 means no signal reduction, 3 equals signal reduction to 33%

[Sonar]
Detection time=5 ;[s]
Sensitivity=0.1 ;(0..1)
Waves factor=1.0 ;[>=0]
Speed factor=20 ;[kt]
Enemy surface factor=200 ;[m2]
Lose time=30 ;[s]
Thermal Layer Signal Attenuation=5.0 ;[>0], 1 means no signal reduction, 5 equals signal reduction to 20%

In the stock game if you were at 320 feet, even running at flank speed they wouldn't be able to hear you let alone get an echo, because the stock game settings are beyond crazy. I would guess if you look at that file in FOTRS you'll find they went overboard in the other direction, possibly some middle setting would work better - my personal hacking goals are challenging but not impossible.

In real life thermal layers are varying strength and depth, no way I know of to simulate that in this game.

Don't recall trying FOTRS, but all the other super mods I've tried seem to focus on making everything more difficult. If the arcade style "GAME OVER!!" happens too frequently, I'd suggest editing the files to make the depth charges/AI sonar a little less accurate and/or less damaging.

Yankee Search Baby

[jericho791]

Well, thanks for all the responses!


I'll have to check the DC sim file.



I guess I was trying to ascertain whether the game actually "sets" a depth on the charges, or if its just programmed to detonate within some percentage of your actual depth. That would explain the pinpoint depth charging at 320 feet.


Not sure if FotRS modded the depth charge files or not. I've been through a lot of the files, and it seems like mostly they copied whole folders if they made any changes at all to files in them.

[KaleunMarco]

Originally Posted by Sniper297

I'd have to hunt through SINK 'EM ALL to find the exact year, but best I recall the "Alka-Seltzer" bubble decoy (copied from the German "pillenwerfer") wasn't available until 1943 or 1944. Stock game has them available at the beginning, although you only get 10 per patrol and they only last 10 minutes.

it was late in the war...possibly even 1945.
the delay was in the testing and initial implementation: new device that required BuShips to reverse engineer another opening the pressure hull.

i am not home at the moment otherwise i would look it up.

[propbeanie]

Originally Posted by jericho791

Well, thanks for all the responses!


I'll have to check the DC sim file.



I guess I was trying to ascertain whether the game actually "sets" a depth on the charges, or if its just programmed to detonate within some percentage of your actual depth. That would explain the pinpoint depth charging at 320 feet.


Not sure if FotRS modded the depth charge files or not. I've been through a lot of the files, and it seems like mostly they copied whole folders if they made any changes at all to files in them.

They were previously modded in FotRSU, but back in the days of FOTRS and / or TMO, and have not been touched in years...

The thing with the depth charges is a lot like that thing with the torpedoes and shells used in the game, in that a certain ammunition has a given strength. When something is "shot" at an enemy (friendly), there is a "roll of dice" (random number generator) as to where it will hit or miss. If it "hits", there is a roll of the dice as to how strong of a hit it is. If there is a miss, there is a roll of the dice as to how strong that miss is, as to whether or not there will be "near-miss" damage. Depth charges especially do that. So you have a minimum and a maximum "zone", or sphere around where the depth charge "explodes". If your submarine is within the "minimum" to zero range, you will incur the full impact of the depth charge, which often exceeds an area's hit points. If that happens to be by a "seam", or bulkhead, you might have two compartments destroyed, and start getting the "We have heavy flooding!" "Medic!!!" and then the spinning screen for "end of game sequence".

If you are between the minimum and maximum, then the dice roll (random number generator) is used to determine how much damage you will incur. Might be minimal, might be maximum. In other words, you might have an explosion at the outer edge of the damage zone that damages all sorts of "equipment", including a bulkhead breach - if the "roll" is not in your favor. It seems that the deeper you are, the more damage you will incur. If you are just outside of the maximum distance of the zone, then no damage at all.

Similar settings is why the torpedoes sometimes will not sink a small merchant ship, and the next time one will take out a large merchant - besides where you hit the ship. Though the torpedoes are set "tighter" and are less "random", there really should be more of a difference between a 1942 torpedo explosion, and a 1943, in that in 1942, you could have an explosion that was not full-force...

[Bubblehead1980]

Originally Posted by jericho791

Well, thanks for all the responses!


I'll have to check the DC sim file.



I guess I was trying to ascertain whether the game actually "sets" a depth on the charges, or if its just programmed to detonate within some percentage of your actual depth. That would explain the pinpoint depth charging at 320 feet.


Not sure if FotRS modded the depth charge files or not. I've been through a lot of the files, and it seems like mostly they copied whole folders if they made any changes at all to files in them.

Yes. The AI detects you at 320 feet so say it drops 4 depth charges, it sets the pattern so they all explode at or within 15 meters of the depth they have you at based on last sonar contact. One of those will likely be at 320 feet, other three will be within 15 meters(if that is what the "depth precision" is set to in the .sim file for the depth charges. More charges, more likely pattern will cover various depths. However, it depends on how deep the water is as well.

For example, last night was running a patrol January 1945 off China Coast, attacking a large convoy that was running the coastal shallows(as they did in real life after Oct 1944) . Tried a night surface attack but light conditions were bit too bright. Escort spotted me, ran away on surface hit him with a torpedo and sunk him. Other escorts closed in but could not find me. I raced ahead and the convoy was now in waters 140 feet deep, enough to dive and evade, especially if make a high speed submerged run to the east, could find the deep waters. I dove, made a night scope attack, sunk two large freighters. Dropped decoys and slipped away to "deep" water with bottom at 260 feet. A nasty escort(Type C in TMO) located me while others chased decoys and let loose two nice patterns(with all the launchers plus racks can let loose 18 charges in a pattern) I happened to have the free cam on so could test my "late war depth charge" mod. I set depth precision to 15 meters. Most were above the sub a couple exploded at my exact depth, some others below me.

Hit points from the charges are in the .zon file. Charges are to have hit minimum hit points they have when exploded at certain distance and maximum. Default in TMO is if a charge explodes within 4 meters, you will take the maximum hit points, if exploded between 4-20 meters away youll take below the max and above the minimum. at 21 meters will take no hit points. At 20 meters, will likely take so few won't notice.