Work in Progress-Thermal layers...RELEASED

[HEMISENT]

Guys, ever since the pinpoint drops thread of a couple months ago I've given a good bit of thought to realism for the sake of realism v. realistic behavior. We are never going to get absolute 100% realism the way this game is modelled. The best we can hope for is to modify, edit or tweak different settings in the attempt to give us all a somewhat more realistic, immersive behaviour based on but not limited to historical values. One of the areas that was the subject of a lot of back and forth discussion going back to SHII days was thermal layers.
I'm not getting into the part of whether or not they were charted, measured, able to be defined by the individual commander or even if they were an absolute ironclad way of escaping detection. The point I think we can all agree on is that they existed, they were located at different depths and the wise U Boat commander could use them to help get out of harms way if he was aware that his boat had entered into a thermal layer. At the end of the day they were a random element that could be useful in evading detection.

Thanks to Redwine's words of encouragement for sort of getting me back involved in this. Here's what I've been working on:
Right now using TT's mini tweaker I've edited the settings for all the active and passive sensor lines in the AI_Sensors.dat/Min Height =. By default these are all set at -300
For testing purposes I've set the active(sonar) at -200 and the passive(hydrophone) to -180. Testing this setting in the U 505 mission, once I've gotten the attention of the escorts I CD'd to 160m. The escorts were pinging like crazy making dc runs as normal. I crept down to 180m and noticed the green stealth meter begin to dirty up around 178 and go totally green in the low to mid 180's. If a DD began pinging the meter would instantly go red again.Creeping down to 200m with Escorts pinging the stealth meter again would dirty up just before 200 and continue to flicker until arounf 205m. The DD's continue to drop on the last, known position but eventually lose contact and disperse.After awhile knowing the pinging has ceased because the escorts are leaving I bring the boat back up. The meter stays green as I rise until I ordered ahead flank at around 190m and the meter again goes full red. Once I reduce speed the meter gradually goes back to green.
I've run this with both the U 505 mission + a DD test mission I made. results are identical.

Using the Random folder function in SH3 Commander I've now got a total of 20 random folders. I'm thinking I'll make 5 copies of the AI_Sensors .dat file. Each copy will have the Min Height= settings for active & passive sensors changed. Basically I'll spread the values out. Starting with a shallower "thermal layer" around 90m. the second around 130m, the third around 190m, the fourth around 220 and the fifth very deep at 260 or 270.

I would appreciate some feedback on this + I've got a couple questions for those more knowledgable than myself.
1.Inserting these 5 files in my existing 20 random folders makes the odds of stumbling into a thermal at 4:1. Are these odds too short? should I increase the percentage by increasing the number of random folders?
2.Was active pinging able to pierce the the thermal layer requiring that the Min Height= setting be deeper than the passive hydrophones? Or did the ping bounce off yet still allow some hydrophone detection meaning the active should be set shallower than the passive.
I do not want an absolute detection floor here. I'm looking for a bit of variation.

Also, keep in mind that there are 16 settings involved in both passive(8) & active(8) sound sensors. Some are early war and some are later. Each set can be can be edited differently. . In the above scenario perhaps 3 of 4 DD's has older sensors not able to pierce a 180m thermal but the remaing ship has a later model that will allow a bit deeper detection. The variations are limitles as you the U Boat Commander never knows which tyupe of sensor is fitted to the attacking ships above you.

http://rapidshare.de/files/14129754/...rs_Mod.7z.html

SH3 Commander-ready to use

http://rapidshare.de/files/14217696/Random.7z.html

[Axlwolf]

Looks very interesting..sadly i don't use SH3 Commander
It's not possible to make something similar in the stock game?
Some new destroyer with the same name but different sensor?
Mmmm...maybe it's too much work

[Church SUBSIM]

This is amazing. Simply amazing should you get (and it sounds as if you have) a really stable mod. I'll say it for everyone here .... Thank you!

It is my understanding that the active sonar would bounce but that was determined by range of the contact. The further away the better the chance it would skip off the layer like a rock on water. Passive, dependent on the quality of the sensor, had a better chance of detection through the layer. It has been some time since I read up on that but I will dig up some of my old reffrence books. So my initial thought is passive is deeper....digging through my books.

Wow .... I can not believe how fantastic this mod would be. Once again Sub Commander proves it's a hell of a program. Almost as valuable as a good solid brain ;)

[Axlwolf]

I've made a small research,it seems that the most affected would be the passive sonar.
I'm not expert,but i'm trying to help

[Ishmael]

I spent 6 years as a sonarman in the US Navy. Over that time, I made countless Bathythermograph drops to predict ranges so I'll throw in some of my experience here. Thermal layers exist in any area where the weather warms the surface of the ocean. The actual layer depth will vary by time of day(shallower in early morning, deeper in late afternoon to early evening), as well as time of year and ocean area. Obviously spring & summer months as well as the closer you get to the tropics will increase the depth of the surface duct and make the layer deeper. Also, the warmer the temp, the greater the temp change at layer depth & the sharper the cutoff of sound. The cooler the surface temp, the weaker the layer.

As a general rule of thumb, below layer ranges for both active and passive will be approx. 1/5 of ranges in the surface duct. So if your above layer range is predicted as 5000 yds for active sonar, below layer range will be around 1000 yds or less.

Below the layer a shadow zone is created as the sound is bent two ways, up along the surface duct, and more vertical towards the ocean bottom. Changing a sonar's depression angle can work somewhat, but is not a cure all.

If you're attempting to model this in game, remember winter months and colder latitudes will most often give you a thermocline, a basically unchanged temp profile for depth and, therefore, no layer. I hope this helps you in your research.

[HEMISENT]

After some checking it looks like the active would indeed bounce off a thermal layer yet passive listening might still be possible. Going along with that train of thought I've reversed the settings. My AI_ Sonar setting is shallower and AI_Hydrophone deeper. I've left a seperation of 10-15m between the two just like in the first tests which allows for a bit of variation. Then just to throw in a bit more of a mix I've changed the individual named active & passive settings to varied depths + or - 3 to 5 m. The later war units I've given a bit deeper capabilities and the earlier sensors set a little shallower.
My concern was if I only had 5 Thermal layers in the loop and I ran into say a layer at 260m I knew the exact depth that applied to all sensors. With the variations It now throws a little uncertainty into things. Especially if I've got a damaged boat that's right on the edge.

Just finished plugging all this into Commanders random folders and will see how it works.

[HEMISENT]

Thanks Ishmael.
Dated random modelling may be possible but I would have to run that by Jscones who built Commander I think He's using it in his waves options, different degrees of storms/wave height depending on season. I know that normal date activation is pretty easy. Geographical I know is out of the question. As far as ranges and sonar angles go I haven't a clue how that would be modelled. A lot of guys put in a whole lot of hours on that subject Jungman, Redwine and Caspofungin to name just a few. This gets into the realm of realism v. realistic behavior. Probably about the best we can do here is come up with something like realistic behaviour circa early to mid 1940's.

Semper Fi

[VonHelsching]

Determined people will nevere cease to inspire me...
This is excellent news.

My 2 cents from some reading I've done in optics physics some years ago (should be relevant)

a) Both passive and active will be affected. The originating wave (from the u-boat engine or a ping) will somehow "slpit" in parts, thus making the location of the vertical coordinates of the origin more stochastic
b) Passive will probably be acffected less since the wave has to travel only one way: u-boat engine ---> thermal ---> DD hydrophone
c) Sorar (active) will probably be affected more since the wave has to go back and forth: DD sonar ping ---> thermal ---> u-boat ---> thermal ---> DD sonar

My gut feeling tells me that the sonar signal should be less that 50% accurate from the u-boat engine sound, if both waves had the same instesity, which they don't . All these, of coure depending on how "solid" is the layer (difference in temperature?)

Anyway, other than my pseudo-scientific soap box, I have a question (and a proposal):

I am preety sure that a solution through SH3cmdr will be found...

As for the geographic attribute being out of the question, this can be partially circumvented (see the "Med" opdion in SH3 random weather generator application)

The question is how the player will know that there is a thermal layer to protect him...

:hmm:

a) Idea #1 a limited cheat-o-meter that functions only when, say. >60 m. depth
b) Far out Idea #2: An external application that reads both the current randomized AI_sensors depth and the current depth of the players -uboat, and reports it in e.g the system tray, or a small transparent icon - after, of course, the player has reached or passed the thermal layer zone...

Anyway, Hemisent you rock

[HEMISENT]

Originally Posted by VonHelsching

I am preety sure that a solution through SH3cmdr will be found...
As for the geographic attribute being out of the question, this can be partially circumvented (see the "Med" opdion in SH3 random weather generator application)

Great idea never thought of that another question for Jscones upon his return.

Originally Posted by VonHelsching

The question is how the player will know that there is a thermal layer to protect him...

The player would not know for sure. Adds to the suspense as in real life the captain might have an idea but not for certain if he stumbled on a protective layer or is something else going on like the DD's sitting, totally shut down and listening while others pretend to leave.???

Is a 1 in 4 chance of stumbling on a thermal layer to much-should it be 1 in 6 or perhaps 1 in 10? Commander will accept addl random folders to lessen the odds

[Rubini]

Hemisent,

A wonderful idea! Can I test too? I'm playing and playing the game in the last days. Maybe i can notice and comment some news in game...

Rubini.

[HEMISENT]

Hi Rubini.
Right now I am using Caspofungins AI_Sensors.dat file. I'ts working really well giving me the DD & DE behaviour we were all looking for from the pinpoint drops exercise. It is this file that I have modified the Min Height= settings. I have 5 modified versions in the Random folders plus His original/default that I can get to you or I have the 5 modified versions set up to test individually with the mod enabler. Call it Min Height mod 1 thru 5. PM me and let me know which you prefer. Keep in mind that I'm just now starting a fresh campaign mission. I intend to use Gibralter for my test area and enable the individual files one at a time and compare. I hate using single missions for anything other than the most basic of tests as they play differently from campaigns.

It's getting late right now so I'm calling it quits for the night-more tomorrow.

[VonHelsching]

Originally Posted by HEMISENT

The player would not know for sure. Adds to the suspense as in real life the captain might have an idea but not for certain if he stumbled on a protective layer or is something else going on like the DD's sitting, totally shut down and listening while others pretend to leave.???

Are you sure that there was no way to know? Any external sensors on the u-boat?

BTW, this doesn't mean that it had to be true, but in AOTD ( ) one of the crew would say "Passing a thermal layer, sir"

[Church SUBSIM]

Thought this was a interesting read ....
from (http://www.fleetsubmarine.com/bathythermograph.html)

"The Submarine Bathythermograph"

"Once submerged, a World War II vintage submarine was severely limited in its options. With the exception of the late-war German Type XXI and Type XXIII, capable of a submerged speed of 16 to 18 knots, and the even more sophisticated Japanese I-201 class, which could manage 19 knots submerged, and none of which had any significant effect on the war, World War II submarines were limited to a top underwater speed of 9 to 10 knots. At that, such speeds would quickly drain the batteries, with the result that the effective speed of a submerged fleet submarine was barely three knots.

With these limitations on speed and endurance, a submarine couldn't effectively run away from a pursuer. The only option was to hide, trying to maneuver to avoid being caught in the escort's active sonar.

Research had discovered that water temperature often varied with depth. Even more importantly, the changes in temperature were frequently fairly abrupt, so that the sea water would form layers. It was soon discovered that these thermal layers affected sonar performance. Below a thermal layer, a submarine's active sonar performed poorly when trying to acquire a target. Conversely, a surface ship's sonar pings were reflected and scattered by the layer as well, allowing the submarine to hide beneath it.

The American Submarine Bathythermograph, such as the example here installed aboard U.S.S. Cod, was devised to take advantage of these thermal layers. The bathythermograph recorded a combined depth/temperature trace on a carbon-coated card. As the boat descended, a stylus rubbed off the carbon from top to bottom on the calibrated card. A second control rod moved the stylus laterally as the temperature rose and fell. (This is essentially the same way an Etch-A-Sketch® works, but with a simple automatic system controllng the stylus.)

If the trace shows a relatively straight line from the surface to operating depth, the water is said to be isothermal. This sort of water provides ideal sonar conditions, but isn't very good if you're trying to hide from sonar. A positive (temperature increase with depth) or negative (temperature decreases with depth) temperature gradient provides better conditions for evading enemy sonar. The best conditions are found when the temperature abruptly rises or falls several degrees within a few feet of depth. Getting below such a layer could drastically reduce a submarine's chances of being detected.

One factor that could affect the ability to hide under a layer was the size of the submarine itself. Diving at an angle, it was possible for the bow to be below the layer while the stern had yet to pass below it. If a commander wasn't careful, it was also possible for the upperworks to protrude above the layer.

Temperature layers, and their effect on sonar performance were known in all navies of the period. The United States, with the development of the Submarine Bathythermograph, was simply the only one to create a simple, effective device to exploit it. The rest had to rely on noticing temperature changes on a thermometer."

It sounds to me as if in the '39 - '44ish years they were just learning about this.

and then there is this from the same site....

"Hydrophones, Sonar, and Other Listening Gear"

A number of devices were used both to detect submerged submarines, and to allow those same submarines to locate their targets without having to surface or raise the periscope. The earliest of these devices were hydrophones.
Hydrophones:

Hydrophones are extremely simple in concept. In the most basic form, a microphone is extended through the bottom of the vessel. By rotating the microphone, the sound operator is able to listen for propeller and machinery noises that might indicate the presence of a submarine.

It didn't take long for the engineers to realise that a pair of highly directional microphones, separated by a few feet and able to be rotated at the centre of the connecting bar, would be more efficient than a single microphone. With each microphone feeding into the operator's corresponding earphone, a skilled operator could get a more accurate bearing on the sound source.
jp hydrophones

Between the wars, this concept was developed. The American "JP" submarine hydrophone was a simple, highly-effective design. Essentially, a long iron bar with a coil of wire wrapped around it. The back was covered with a sound attenuating material, so that it was relatively insensitive to sounds coming from the back. This was mounted on a shaft, with a hand wheel in the forward torpedo room that the operator used for training the head. When necessary, the operator could plug the cable into a power source to remagnetize the iron core. (Hard blows can demagnetize magnets, so this type of hydrophone can stop working after a close depth charge detonation until the core is remagnetized.)

The "JP" head was mounted on the upper deck of American fleet submarines. In this position it could pick up the sounds of surface vessels easily, without interfering sounds from within the submarine's own hull. Anti-submarine vessels, of course, mounted their hydrophones below the waterline. When the submarine was surfaced, the the "JP" gear was secured (turned off).

magic eye

One device used to aid the operator in zeroing in on the target bearing was the "magic eye" on his amplifier panel. This was actually a special vacuum tube, with the top sticking out through an opening in the panel. A phosphor coating created a pie-shaped image on the top of the tube. Older people will remember the same sort of device used as a tuning meter on old FM radios. As the signal gets stronger the "pie" gets narrower, until it becomes a line at peak strength. The operator could watch this to augment his own listening skills.

While hydrophones alone could give a bearing on the target, they were severely limited in their capabilities. Range had to be estimated based on things like sound volume, which called for a lot of skill and experience on the part of the operator. Target speed was more easily determined, since the operator could count the revolutions of the submarine's propellers. As long as adequate intelligence was available on the type of target—particularly the propeller pitch—a fairly accurate determination of its speed was possible.

Presuming the target's screws have a pitch of 36" (that is, a single revolution of the screw will move the vessel forward by three feet), if the screw is turning at 100 rpm, the target should travel 300 feet in each minute, or 18,000 feet in an hour. Dividing that figure by 6,076 (the number of feet in a nautical mile), gives a target speed of just under 3 knots. (This isn't particularly fast, obviously, but for most submerged submarines prior to the advent of nuclear power it wasn't particularly slow, either.)

A major limit on the effectiveness of hydrophones was the speed of the vessel on which they were mounted. Anti-submarine escort vessels tended to be relatively slow, often with a top speed on no more than 18 knots. There were two reasons for this. First, the vessels they were escorting were usually even slower, so high speed wasn't needed to keep pace. And, more importantly, the effectiveness of their detection gear diminished rapidly as speed increased. At full speed, the range of a destroyer's hydrophones was so limited that they would probably have to hit a submerged submarine in order to detect it. The noise of the escort's passage through the water created this problem. In fact, for this reason destroyers were not generally used as convoy escorts in World War II once purpose built warships—sloops, corvettes, frigates, or destroyer escorts—became available.
ASDIC (Sonar):

During the First World War, Allied scientists addressed the problem of submarine detection in the hope of finding something more effective than hydrophones. The result of their investigation was called Asdic by the British and Sonar by the Americans. (Asdic is an acronym for Anti Submarine Detection Investigation Committee; Sonar comes from SOund NAvigation and Ranging.)

The simplest form of Asdic combined hydrophones with a sound source. The emitter sent out a sound pulse, which would reflect off the target. The length of time it took for the sound to travel to the target and for the echo to return could be used to calculate the range. This is actually the same principle used by an echo sounder to determine the depth of water.

In the period between the wars, Asdic was sufficiently developed for the British Admiralty to come to believe that it had rendered the submarine impotent as a stealth weapon. It took only a few weeks for them to realize that it was much easier to acquire a target in an exercise (where the A/S vessels knew there would be one around somewhere) than in combat, where the captain of the U-boat was going to do his best to remain undetected.

Of course, anti-submarine forces weren't the only ones using detection gear. Hydrophones were fitted to submarines at an early stage of development. Range was significantly enhanced in a submerged vessel, both because a submarine's electric motors were quieter than a surface ships engines, and because of the elimination of surface noises. By the end of World War II, German hydrophone operators could detect enemy surface ships at ranges of as much as 50 miles.
submarine sonar head

Sonar was a mixed blessing for submarines. It could be used to give an accurate range and bearing on a surface target, but the emitter also provided a bearing for the enemy's A/S forces. (Radar has always suffered from the same blessing/curse syndrome; it warns you that the enemy is coming, but also tells the enemy where you are.) The Sonar head in the picture was part of the Sonar suite on an American fleet submarine, and could be retracted inside the hull when secured.

Pre-war American submarine theorists were so confident of the capabilities of Sonar in submarines that doctrine called for all attacks to be made submerged, using only Sonar, and never exposing the periscope. It was believed that radar had developed sufficiently that exposing the periscope was too great a risk. As it turned out, periscope attacks remained as the primary method, since the Sonar attack methods resulted in too many misses. Also, Japanese warships were slow in adding radar to their equipment, but their escorts proved to have excellent sound gear, so the American Sonar emitters provided a better target than the exposed periscopes. For this reason, the emitters were usually utilized on a single-ping setting for rangefinding, rather than in active searches.

Since a Sonar transducer combines an emitter with a receiver, it could also be used to listen for an escort's Sonar. When this happened, the head could be rotated to get a reciprocal bearing. Escorts generally emitted continuously.

Modern submarine doctrine calls for boats to be equipped with powerful, highly-sophisticated, active sonar, and for that gear to almost never actually be used. Most detection is still accomplished using a modern incarnation of the old hydrophones, though now linked to a suite of electronic gear that gives far more information than the old-time operators were able to obtain just from listening. The equipment is now sophisticated enough that ranges can be determined using passive detection gear, for instance. At the same time, operator skill is still the most important factor. Contrary to what turns up in a lot of techno-thrillers, computers don't do nearly as much in the way of analysis as many people think, and contacts are still identified mainly by the operators based on skill and experience, though that skill is augmented by very sophisticated equipment.

Up through World War II, submarines were mainly used in an anti-shipping role. Initially, the targets were surface warships. Germany recognized the utility of the submarine in the role of a commerce raider early in World War I. That role was developed to its ultimate in World War II, where Germany attempted to use its U-boat force to shut down the convoy routes from the U.S. to Britain. (Though never as successfully as either side suggested.) American submarine forces in the Pacific actually did succeed in the virtual destruction of the Japanese merchant fleet. At least, they were able to do so once the torpedo problems were finally solved after about a year and half of frustration.

Today, the primary target of a submarine is usually another submarine. Hence, the importance of silent operation. The submarine that hears its enemy first will usually be the victor in such an encounter."

[HEMISENT]

Originally Posted by VonHelsching

Are you sure that there was no way to know? Any external sensors on the u-boat?

BTW, this doesn't mean that it had to be true, but in AOTD ( ) one of the crew would say "Passing a thermal layer, sir"

Nope, I'm not sure 100% one way or the other. I've read that there were ways of checking temperature and even ways of determining salinity. Of all the books and interviews I've read over the years it seems that there are just as many reports confirming thermal layer detection as there are in denying it. Personally, I like the idea of "stumbling" into a layer by chance. But thats just me.

I never played AOTD but SHII had the same type of message.

All I'm looking for is a way to add a little more immersion and suspense to the game. As far as a thermal layer detector warning device I do not have those kind of skills but I'm sure that some of the modders would have an idea.
First things first tho-more testing.

[Redwine]

Hemisent....... Teacher !!

Backing home from a long travel, and what a surprise !

Let me know if i can help.

I think so it need lot of test, so determine wich sensor is better to "nerf' or make deaf under determined depth, pasive only, active only, or both......

May be the random system may include all posibilities, pasive only, active only, both, and no one, with many diferent setting each one.

To all guys...... plese boys, help and support for Hemisent in this project