TMO Questions

[Lionfish298]

Hello all.

None of you know me. I lurk on the boards and quietly read what you lot are saying, I suppose in true submariner fashion. But if I am a submariner, I am a frustrated submariner. I recently installed Trigger Maru overhauled with the patch and the lovely 3D interiors. I was flabbergasted immediately at the sheer amount of, well, awesomeness, that this mod created.

However, I am experiencing something rather frustrated. The Destroyer patrols outside of harbors (my favorite stalking grounds) have gone from being almost mentally handicapped in the stock version of the game to being psychic and omnipresent.

I recently was given command of the USS Wahoo, one of my favorite WW2 boats to read about. I was ordered out to the Mariana Islands to patrol in "Parlor" and saw absolutely nothing except for patrol aircraft. So, I decide to sneak down to Guam. The water is fairly deep until you get in close, and it's always been enjoyable for me to prowl up to the harbor, pump the parked freighters full of fish, and then get the hell out of there before the Destroyers can find me. I have been quite unable to do this with Trigger Maru. I do understand that the developers have beefed up the AI, am I correct in this? I must be, judging from their behavior.

About 4 miles out from the island, with radar bearings on the lone destroyer patrolling, I submerged to a nice comfortable 200 feet or so, rigged for silent running, and called for battle stations. I start creeping into the harbor -- first at 2/3 and then down to 1/3 -- and what does my sonar discover? That Mr Destroyer is charging in on me full blast, dropping ash cans exactly at my depth, without me ever going over 2/3 and above a thermal layer. Now, I have read a whole hell of a lot of literature on WW2 submarine warfare, but this sounds a little bit fantastic to me. The water was still deep enough, so I ducked down beneath test depth down to 500 feet. Still, Destroyer-san continues to bracket me with depth charges even though I ought to have become a ghost by this point. Finally, I'm at All Stop and pretty much laying on the bottom and he finally starts nosing around elsewhere. I start creeping forward at 1/3 and start following the contours of the ocean bottom. About this time, I got paranoid and saved the game, having a premonition of having a repeat of my original discovery. To prevent this, I stop the submarine again and ever so gingerly start creeping toward the surface. When I hit 150 feet, I switched to the external camera just to see what's going on, and the fracking Destroyer is barreling back down on me full tilt, spewing depth charges in his wake. Mind you, he's not even actively pinging (which surprised me), he's just charging madly at me. Needless to say, my career ended with a fate similar to that of Mush, but far less illustrious.

Now, I want to know, how did the Japanese navy secure demigods as the captains of the destroyers? And how the hell am I supposed to sneak past them?

Thanks guys, the TMO mod is amazing, still, I'm just frustrated by these destroyers.

[I'm goin' down]

I too play TMO. Ducimus programmed destroyers to kill, plain and simple. Coincidentally with a depth charge attack, my computer motherboard was destroyed. Of course I know that a TMO destroyer was responsible. I submitted an insurance claim, which the insurer invesitaged and denied. The grounds for denial of indemnity was that a loss caused by an Act of
War is not covered -- i.e. it is excluded from coverage. So, I bought a new computer, and have sent Ducimus the bill!

Anyway, here is a view of what it looked like in the last moments of my previous life.The screens shots are compliments of scudhawk, and they pretty much show the what the end lookede like.

When you see this, say GOODBYE.


Originally Posted by scudhawk


Depth charge compliments of TMO1.9.

[I'm goin' down]

Destroyers wreaking havoc in TMO1.9? It is pretty simple, really. Ducimus programed TMO destroyers to kill. That's it in plain English. To paraphrase Pecos Bill, when a young man said he was planning to ride Widowmaker, Pecos' horse, "You try to ride Widowmanke and he'll kill you."

Coincidentally, my boat was destroyed by a depth charge launched during an attack run by a destroyer during a TMO1.9 mission at the precise moment that my computer motherboard crashed permanently, suffering the Blue Screen of Death. Convinced that TMO1,9 was responsible (collateral damage?), I filed a claim under my homeowner's property insurance policy for purposes of recovering the replacement cost of my computer which was rendered useless by the dastardly attack. My insurer denied the claim, stating that a loss incurred as a result of a depth charge is not covered on the ground that it falls squarely under the exclusion to coverage for losses incurred during and attributable to Acts of War. @#$!!

Below I present images of what it looked like from a periscope view of the SS Barbarinna in her last moment. The screen shots are borrowed from scudhawk, in what has to be one of the greatest screen shots ever posted in the silent hunter forums.

When you see this, say GOODBYE.

Originally Posted by scudhawk

Take a deep breath and hold it, for it will be your last!

[Wilcke]

In the readme there are a couple of notes on detuning the tin cans and also how to make the thermal layer into kevlar.

Happy Hunting!

[Lionfish298]

Well, I mean, I don't want to just play the game like a wimp. My surprise was just at how all-knowing the Tin Cans were and that it didn't seem very realistic. Am I incorrect in my estimation of the Japanese? Have you tuned them up to make their hunting skills as they were during the war, or did you tune them up beyond that just to increase the difficulty?

Also, you mention turning the "thermal layer into kevlar". How realistic is the modeling of the thermal layer in TMO?

[I'm goin' down]

Ducimus posted a link to a tutorial on avoiding dds radar. I am not going to look for it, but a link is posted in Rockin Robbins sticky in the main forum for sH4 under the Skipper's bag of tricks. If you are looking for what he did and why, Ducimus has it explained it in the TMO thread or will have to weigh in. But I assume that he used the information in the link. Enemy radar capability increased in quality, range and depth according to the information in the link.

[Lionfish298]

Right, so I read the article that you pointed me towards. It is rather helpful, but I have a few questions. He says:

The obvious solution early war is to dive to around 230 meters or so and stay quiet as a mouse. Pretty simple no?

And

Again, the obvious answer to late war sonar is,
"yes, Deeper still!"

230 meters is over 700 feet, yes? I was not aware early war submarines could dive that deep. I lost the USS Flying Fish after some heavy flooding caused us to go below crush depth and she cracked around 650-700 feet. If late war sonar goes even deeper, than I'm thinking it sounds rather impossible to dive "under" his sonar cone. Is this correct? Or does he mean "feet" in that FAQ and not meters?

[I'm goin' down]

It is probably a mistake and should say feet. But I do not know for sure. Send a message to ducimus and rockin robbins, they might know.

[Ducimus]

As stated somewhere in the first paragraph of said article, i originally wrote that for SH3, but the same principles apply.

[Lionfish298]

Originally Posted by Ducimus

As stated somewhere in the first paragraph of said article, i originally wrote that for SH3, but the same principles apply.

I don't mean this to sound priggish, but that doesn't really answer my question. The article says 230 meters and suggests going to deeper depths. That seems way too deep for American fleet boats in the Pacific. Is this so, or am I incorrect?

[I'm goin' down]

Originally Posted by Lionfish298

I don't mean this to sound priggish, but that doesn't really answer my question. The article says 230 meters and suggests going to deeper depths. That seems way too deep for American fleet boats in the Pacific. Is this so, or am I incorrect?

I am sure there is literature on the web re the diving depth capabilities of the boats. You might want to research it.

Bulletin No. 31

Test Depth and High Yield

Prior to our most recent publication, "Steep Angles and Deep and Dives" SRC received several inquiries regarding a definition of HY, (high yield) as well as the relation between test depth and crush depth. It is difficult to discuss these concepts without also discussing hull strength. "Steep Angles and Deep Dives", available from SRC for $13.95, provides a comprehensive explanation of submarine hull strength from the pouring of the molten metal to the welding of hull plates. These explanations are sandwiched between narratives of harrowing dives that took American submarines far below their test depths.
The following excerpt is from the hull strength introductory chapter of "Steep Angles and Deep Dives". It provides some basic information on submarine hull strength including the definition of test depth and high yield:
Test depth is a theoretical number corresponding to the amount of area pressure that can be applied to a hull before it is violated by either distortion, warping, buckling or cracking. The pressure hull acts to prevent an equalization of pressure on both sides of the hull surface. When pressure is equal on both sides of a hull, such as is the case in a submarine's external ballast tanks, there is no need to attend to the problem of potential collapse.
Test depth can be thought of as an engineering estimate of what pressure will be required on one side of a hull to breach the hull, taking into account such factors of hull strength as hull diameter, hull thickness, framing, and intrusions. Naval engineers tend to be conservative in their estimates and the varied factors tend to render an estimate as just that, an estimate. The engineers back into the problem by first estimating the crush depth of a hull, then creating the theoretical test depth by a applying a decimal factor to the crush depth. Different national navies apply varying factors. The United States Navy has used a factor of 1.5, but this has changed many times. Of course, computers are able to make such estimates much more trust-worthy, however, the accounts described "Steep Angles and Deep Dives" are, for the most part, in hulls designed before the advent of the computer.
In the American Navy, hull designers depend on the experience of submarines to verify their estimates. Buships requires a submarine captain to immediately notify both Buships and the Chief of Naval Operations in writing when a boat under his command exceeds test depth. The captain's professional career may be jeopardized by a zealous attention to recording a dive that went wrong. Only in wartime can a captain reasonably explain the need to exceed test depth. For this reason submarines exceeding test depth sometimes fail to make note of the dive in their deck logs.
The simplest application of determining hull strength is the hull thickness. The thicker the hull metal the stronger the hull and the deeper the test depth, assuming all other factors are constant. Prior to the Balao class U.S. submarine, hulls were built of mild steel (MS) which had a maximum tensile strength of 60,000 pounds per square inch and a yield strength of 45,000 psi with 23 percent elongation. The thickness of hull plating until about 1943 was specified in terms of the weight of a square foot of plate rather than the actual thickness, and this was gradually increased from 20 pound plate (approximately one half inch) to twenty seven and a half pounds per square inch in the Salmon (SS-182).
Another change in the Balao class was the change in material used for hulls. High tensile steel was a chromium-vanadium alloy with a maximum tensile strength of 50,000 psi with 20 percent elongation. When the composition was changed to titanium-manganese alloy, because of wartime shortages, the strength dropped to 45,000 psi. The Salmon's hull was about seven eighths of an inch thick giving her a test depth of 250 feet. Conning tower shells were thicker as protection against surface guns.
The thick-skinned boats came along in 1942 with a test depth of 412 feet. These boats had the same seven eighths inch thick hull as Salmon, but the quality of hull steel ie., high tensile strength steel had significantly improved. The crush depth of these boats was estimated to be around 450 feet. Fleet type submarines built during the Second World War were to last through much of the cold war. These boats have careers that have lasted over fifty years with many still being used by foreign navies.
After the war the Navy built several fast attack submarines. These had hulls about an inch and a half thick. They had a test depth of 700 feet. The same hull thickness and quality of steel was used on the early nuclear submarines.
A modern nuclear powered submarine normally has a test depth of over 2000 feet. This huge increase in operational depth came about from increasing the thickness of a hull, from strides in improving the quality of steel, from improvements in the manufacturing process and in hull framing.
Steel is an alloy made up of several metals other than iron. These may include chromium, nickel, manganese, titanium and a host of others. Metallurgy is the science of combining these elements to produce an iron metal that meets a specific need, in this case a hull which is resistant to sea pressure. During the Second World War Krupp of Germany and others used advanced techniques to produce hull plating of unusually high quality. America inherited some of the formulae and steel mills benefited by the German experience.
The key to producing metal hulls suitable to deep diving submarines is the quality of yield strength in combination with compression strength. Accurately controlled element content and relatively high percentages of alloy additives produces strength. The compression strength curve is relatively flat until it reaches a point where the molecules can no longer bind, then the metal fails by cracking and splitting. On the other hand it is possible to produce a metal hull that has the quality of bending rather than rupturing. It yields under pressure where its elasticity, (elongation) gradually succumbs to increasing pressure. The trick for the metallurgist is to strike a compromise and to use the correct ratio of alloy elements to gain a hull plate that resists pressure to the maximum through high compression strength, but yields enough to forestall the rupturing of the metal.
Steel strength is often measured by tensile strength. In this test the metal is pulled on both ends until it parts. Tensile strength is related to compression strength even though the tests are opposite, one pulling and the other pushing. For this reason submarine steel strength is often measured in tensile strength, not withstanding the nature of sea pressure as a compression force.
American submarines such as the Seawolf and Virginia use HY (high yield) 100 metals. These designators attend to the elements used in the submarine hull's alloy where essentially the higher the number the more resilient and resistant the metal is to pressure.
The combination of elements to produce an alloy with great strength is only half the story of producing submarine hulls. The second factor in the manufacturing process is the tempering of the steel and shaping of the plates into a final form. Once again, the basic concept is that a slow-cooling steel tends to be resilient and a quick cooling steel tends to be brittle. Metallurgists in the middle ages learned this early on and after shaping a red hot sword on an anvil plunged it into water. This gave the sword a fine cutting edge resistant to chipping and dulling. The down side was that when struck by another sword it tended to shatter rather than yield. Thus, a submarine's hull plating is cooled at a specific rate designed to produce the best combination of stress and yield factors.
The shaping of the plate in the factory is accomplished with huge hydraulic rollers. The shaping process is also a compromise. Some alloys are cold rolled. This is the optimum in terms of preserving the alloy's strength in the shaping process, however, as the thickness of the plate increases the effect of the rolling becomes less and less. The modern mill now uses computers to cold roll submarine hull plates. Each pass through the rollers bends the steel a small amount until after many ( in some cases hundreds) of such passes through the rollers the plate conforms to the correct hull curvature.
In determining the diameter of the pressure hull the engineer takes into account the metal thickness that will be required to meet a given strength level. The less the diameter the thinner the metal can be. The size of machinery largely determines the diameters of submarines. As the design of the submarine progresses the diameter of the hull inevitably increases. (Modern Trident missile submarines have a forty three foot diameter pressure hull) This necessitates a thicker hull where the alloys used and the shaping process are constant. Once again, the hull design process is one of compromise where interplaying factors are balanced against one another until a final design with an estimate of test depth is reached.
The curved plates of metal to make up the submarine's hull are further strengthened by frames. Lateral framing was known to the Vikings, although they started with a hull shape and only after the strakes had been laid did they imbed the frames into the preformed hull. Submarine hull strength is in large part a function of frame strength and spacing. Cross sections of frames are normally "T" shaped and can be within the pressure hull, on the exterior of the pressure hull, or both. The externally braced hull was the standard in submarine design, because piping and conduit cannot penetrate frames without compromising strength. With modern welding techniques it has been possible to grip the hull plate to the frame with such force that external framing is successful.
The distance between frames is crucial to determining test depth since this distance is where a compressed hull will yield or fail. The distance is a design function taking into account the factors described in this section.
The cylinder is the optimal shape for a submarine hull. A sphere is better still, however, the shape of a sphere does not accommodate a moving vessel through water. Only in experimental and exploration vehicles is the spherical hull shape used. A submarine is in essence, a long cylinder, made up of many sections welded together.
The tapered ends of the fleet type submarine (forward torpedo room and after torpedo room) called for innovation since the cylindrical form had to be compromised. These compartments were flattened for hydrodynamic reasons. Fleet type boats had exterior framing, however, in these end compartments the frames were interior as well as exterior. The deviation from circularity although small, produced a bending moment putting the shell plating under compression and the face plate of the frame under tension. Thus, the mass-produced fleet type boats had framing partly on the inside and partly on the outside of the pressure hull.
Three dimensional curvature for modern hemispherical bows require conical shaping, and tapered hull plating that in turn requires extensive welding.
The welding of the many plates and commensurate framing necessitates the greatest care. The weld seam must have the same strength as the abutting hull plates. This means that if welding is accomplished by hand the welder must be of the highest technical competence. Although a submarine may be similar to others in its class each is essentially hand built. Automation is limited, but computerization is extensive.
Hull butting is exact. Each cylindrical hull section must precisely match the adjoining section. Each cylindrical section has its edges ground to an approximate forty five degree knife edge. When two sections are mated the two edges form a trough. Actually, there are two troughs, one on the inside of the cylinder and the other on the outside. The welder (or machine) places the first bead at the deepest point of the trough. The next weld layer is placed on top of the deeper layer. As the process continues and the wedge shaped trough widens, more and more beads are placed side by side to fill the trough. Many hundreds of beads are required to bring the level of beading to the surface of the abutting hull sections. It is a long and tedious job and quality inspections are constant.
Unfortunately, a perfect cylindrical hull with precise welding and engineered frame spacing must be punctured to allow various pipes, coaxial cables and rotating shafts access to the exterior of the hull. Wherever such a hull opening occurs the hull must be reinforced by building up the thickness of the surrounding area. The larger the opening (such as for hatches) the stronger must be the build-up. Even when every effort is made to compensate for the loss of strength from a hull opening the point of violation will be the point of failure when the hull exceeds test depth.
Time destroys the hull from several directions. The metal itself fatigues over time. Additionally, the sea takes its toll with corrosion eating at the metal. Hull modifications requiring welding, heat the hull and thereby reduce the effectiveness of the initial tempering. Nicks, gouges and scrapes collectively take their toll.
The Fleet Type boat designed and built during the Second World War were subsequently equipped with snorkels and modified into Guppies. These were often given to other nations under various alliances. Many of these boats are still operating as naval units in foreign navies. They are only now being replaced by more recently built boats.

[Rockin Robbins]

Wow! This is uncannily like my very first post after loading Trigger Maru (not overhauled at that point) for the very first time. I was a veteran of SH3/GWX at the time, so I was quite well prepared BUT I was nevertheless very startled and maybe a bit scared. Let me find and reproduce that puppy, along with Ducimus' response at the time.

Found it here:

Jap destroyers have Superman on board?
OK, I'm playing with destroyers again. Here's something different. I was stalking radar contacts in fog, driving rain, 10 m/sec wind, overcast and daytime. Visibility is about 450 yards, sometimes less. I'm shooting torpedoes on sonar only and just sank 2 freighters that way, six torpedoes, 5 hits, thank you WernerSobe!

Two more radar contacts running six knots north, freighters, right? So I set up ahead, 1000 yards off track and wait for my stern shots. Hehehehehehehehehehe! Watch the radar until they're a mile away. Submerge to periscope depth and acquire em on sonar. Wait for the bearing to be about 350 and it's time to start pinging. Ping. Ping. Target speeding up. Approaching fast!

Hmmmmmmm..... That's not very freighter-like conduct... Oh, @#$@#$%@!!! crash dive. At 110 ft or so hit full right rudder pull back to ahead 1/3 at 180 or so and straighen out the rudder. Ahhhhh a nice thermal layer, rig for silent running, hit the RPM at exactly 1000 RPM, the quietest (that isn't exactly 1/3 throttle, by the way Ducimus) and just wait to slink away.

Three minutes later here's that high speed freight train overhead and he's dropping ashcans right on top of me. Good thing I'm at 260 and have some time. Full left, ahead emergency for a couple seconds and back to 1000 RPM. The event camera came on so he must have been pretty close. He didn't ping once.

Lets go down to 300, change course 90º, lalalalalalalalalalalala. Freight train again. Here comes the depth charges. Right on top of me and I slink out again because depth is my buddy.

This has happened four times now in a 45 minute period. From the beginning mr destroyer has not pinged once. Unless he has Superman up there using his x-ray vision, this is totally impossible. I'm in lousy sonar conditions with a great thermal layer above me, silent running trying both 1000 RPM and your ahead 1/3. He follows me around like a good puppy dog.

Sorry Ducimus, that's way out of the line of possibility. Methinks the AI needs some tweaking. Even in GWX they have to ping you to find you running silent at 1 kt (although these depth charges don't seem as deadly as GWX).

Other than this event, I really have enjoyed TM. Coming from RFB I didn't really expect to, but it seems to me reality is well served here if you ignore Superman up there. Have any kryptonite?

Sounds familiar donit? Then Duci leveled a tommy gun in my direction and put me in my place. In a post, which he later edited to tone down he told me that Trigger Maru had nothing to do with realism and everything to do with challenging game play. I would disagree with that, in that for me realism is in how I operate when playing the game. If I'm scared I'll be killed and not acting like John Wayne with his infinite rounds six shooter, THAT is realism. It takes unrealistic enemy behavior to make you behave realistically. Kapeesh?

A couple of posts later I posted my take on how to deal with the "Superpoop" DDs:

OK, I'm up here on the surface taking a shower again. Radar says Superpoop is a mile away and not moving. It's mighty tempting to go see what I can do with him but I have a shade over 15,000 tons and 8 stern torps left, one in tube 1 up front. I have half a tank of diesel. "Mass tonnage" will never come up when talking about this cruise. Seems to me the uber-AI results in much more realistic tonnage per patrol. Of course you could cheat and return to Midway for refits to extend it. In R/L Admiral Lockwood would have something to say about that.

No sign of any tractor beams or phazers. The destroyers can be dealt with and survival is not that difficult for me. Of course I'm trained on GWX where there are no thermal layers and the U-Boats are slower running silent at 1 kt instead of the American Gato's 2 kt at quietest speed. I'm not going to change a thing because I'm just having too much fun. I'd say if you're getting killed too much you ought to work on your tactics.

Remember, when the destroyer is pinging, he's not listening. Pinging is your signal to hit the throttle and maneuver yourself quickly to a new hidey spot at a different depth and get back to silent running. Pinging does not mean he necessarily knows where you are, either. Inaction is fatal here. Keep twisting. Vary depths with the realization that deeper is better most of the time.

When the charges hit the water, remember his stern is now facing you. Do a radical turn and hit the throttle because you're in the clear for a bit. If he's on top of you dropping ashcans and you sit there, your patrol is over. He can't hear you, he can't ping you right now. Hit the jets and get out of there. After a short spurt, go back to silent running again.

If there are two or more destroyers you can be sure that at least one is always backed away listening. That means much shorter bursts of power reluctantly used only when survival is in the balance. Stay deep, quiet and zigzag like the drunken sailor you are in Pearl. Your goal is to put both destroyers back of bearings 135/225 and the angles progressing toward 180, showing you are leaving them safely astern.

Remember you are moving. When the bearing to the destroyer stays the same, that means you would be on a collision course if you were on the surface. In this case it means that he is either moving straight away from you or is going to pass right overhead. There's a freight train a'comin'. Try to change course to see if his bearing then begins to change, showing he will pass ahead or astern. If the bearing does not change, he's following your turn. Then you have to time the drop and run out from under it as the ashcans fall.

Ducimus, you're the expert! Anything to add? Am I making you want to get out here? I can tell you one thing. RFB is gonna have to wait. This is too much fun.

He came back with one of the greatest compliments I've ever received:

Everyone should read this post by rockin robbins:
http://www.subsim.com/radioroom/show...&postcount=235

This is how to handle the AI in this mod, its how i always intended it. If you think you can just go below a layer, hit silent running and be safe in a psudo klingon cloaking, you got another thing coming. Skipper the boat, its not a pleasure cruise where you stand idley by playing shuffleboard waiting for the DC's to stop.

I guess he was also resuming putting me in my place again.

It's just amazing to me that you put the question just about exactly as I did back in July 2007.

[Lionfish298]

Thanks for the tips, guys! I've tried to put them into practice and I've had some better success. Destroyers are still frustratingly sentient, but they've reigned in my gallavanting to correct.

Anyway, here's another question. I've been having this bug since I installed TMO whenever a ship takes damage. I've seen a few screenies of such things around, but I've never really understood the cause. Is there a fix for it?