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Old 11-07-21, 12:01 AM   #1
Zero Niner
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Default (GFO) Help me make sense of this encounter

It's Feb 1943 and I encounter, for the first time, a tenacious DD off Saipan. He spots me, I dive deep to 250', rig for silent running and steer a course 60 deg away from my original heading. I creep away and I judge that I am far away enough to surface safely but he spots me and charges at me, forcing me to crash dive again. This time he keeps up with me even though I am deep, below the thermocline, running silent. I even stop and he does circles of 8 directly above me. When I creep away at 1 kt he follows me even though he is not using active sonar.
I finally manage to get away from him after almost 2 days underwater - batteries are low and CO2 levels high.

That was a thrilling encounter. Most other escorts I've come across are easy to shake off but not this one. I wonder why. Could there be certain units with AI programmed to be more difficult then normal? Did the IJN equip their warships with a more capable radar? What I found disturbing was that he seemed to know exactly where I was even as I was undetected. Throughout this 2 day encounter not one depth charge was dropped.
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Old 11-07-21, 05:01 AM   #2
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It's Feb 1943 and I encounter, for the first time, a tenacious DD off Saipan. He spots me, I dive deep to 250', rig for silent running and steer a course 60 deg away from my original heading. I creep away and I judge that I am far away enough to surface safely but he spots me and charges at me, forcing me to crash dive again. This time he keeps up with me even though I am deep, below the thermocline, running silent. I even stop and he does circles of 8 directly above me. When I creep away at 1 kt he follows me even though he is not using active sonar.
I finally manage to get away from him after almost 2 days underwater - batteries are low and CO2 levels high.

That was a thrilling encounter. Most other escorts I've come across are easy to shake off but not this one. I wonder why. Could there be certain units with AI programmed to be more difficult then normal? Did the IJN equip their warships with a more capable radar? What I found disturbing was that he seemed to know exactly where I was even as I was undetected. Throughout this 2 day encounter not one depth charge was dropped.

Interesting encounter, especially the two days part. That is some TMO stuff lol surprised caught it in GFO. Kind of a lot to cover, so hang in there lol.


There are five skill levels a escort can have in SH 4

Poor, Novice, Competent, Veteran, Elite and these affect how skilled they are at everything....visually spotting things, use of radar, sonar, hydrophones, depth charges etc.

Poor-Novice-Competent or Incompetent as it should be listed lol are window dressing, but competent or novice is what most escorts were set to in stock and a lot of mods. So easy to beat, generally not very persistent etc.

Veteran is usually challenging, and Elite are very tough, Allied in 1944-1945 level, a bit much at times. Tough as would imagine. Kind of legacy thing with SH4 being a build on SH3.

So I would say you likely ran into a unit set to elite or veteran for once. when usually running into novice and (in) competent.

Sounds like you may have surfaced too soon, wait them out, when they go quiet or are patrolling area, they are listening , your boat makes a lot noise that can be heard on enemy sound gear when it comes to periscope depth and especially when surfaces, the interim when silent running kicks off at 40 feet, and surfacing completely, when the game considers your boat "surfaced" broadcasts your position like a homing beacon to anyone listening.

Literally, as I write this I am waiting out a enemy escort on August 28 1943, who after four hours of depth charging, lost me. I am in Sea of Okhotsk aboard USS Seal SS-183(Salmon Class). Attacked a two ship one escort convoy, firs two new MK 18 torpedoes(eight aboard, four bow, four stern) missed as target zigged just as fired. Transport turned toward my scope so fired "down the throat" from 1000 yards, torpedoes would have hit, but they ran deep. I decided to run with external cam on this patrol to change it, so watched them run deep. The early MK 18 electric had some issues when first introduced, not with duds or magnetic exploders) but depth keeping, gyro issues, battery issues, and circle runs (which remained issue throughout its service in the war). Came to scope scope and 5000 yards off escort is sitting still, listening, so went back to 250 feet and going opposite direction, its dusk now, so in few can surface for end around and attack the convoy at night on surface.


Another reason he was likely on you is when the enemy visually spots your sub and you dive, they know your exact location where you submerged, and AI knows a sub could not have gone far, so they know you are, not just going on sound or active sonar contacts, so in my experience has seemed to contribute to their tenacity in the attack. Think of it like a dog tracking and has picked up a strong scent on its game. Perhaps dog acquired visual at one point but could not catch it, but will follow the nose and knows or has some instinct it could not have gone too far.




Also, sounds like this was a DD on patrol, a sub hunter vs one assigned as escort. I have noticed this alters their behavior, when assigned to a group in the game and marked "position as escort" (mission editor) they tend to behave differently. One behavior is they will attack and hunt etc, but their priority will be to rejoin their charge. Where as a vessel on patrol, not attached to escort will tend to at times, especially if set to high skill level to hunt, wait the sub out longer etc.

Also, moving at 1 kt makes your boat basically a stationary target and does not make you any more quiet. The enemy's hydrophone detects your sub primarily by RPM of motors and the noise your sub makes. When in silent running, the sim has your sub lose much of its sound signature, aside from RPM. Look at your tachometers in the conning tower by the helm and the secondary helm in the control room, will tell your RPM. General rule of thumb is keep it under if ahead 1/3 on silent running is little over 2 knots and is somewhere about 75 rpm, so 1 kt is about 50, but believe it or not, it does not make a difference in if they hear you, its about being on silent running and below 100 rpm, depends on your depth, thermal layer etc. Base this on many, many hours of patrols in SH 4 and years of testing when creating my mods.

Something the sim fails to simulate is disturbances in water created by depth charges, which in reality would give sub a small window where enemy's hydrophones were useless after depth charge explosion. There is a mod in the download section though, it makes the depth charges each produce a lasting noise, gives player that window real subs had. However, its a bit too effective and can neuter most enemies, so I am testing version which reduce the duration of the noise and the noise level, almost have it right.


Which class of DD? That matters. Some have best sound equipment and sonar gear they are equipped with, it depends on that particular vessel and its .eqp file. You said it was a DD , assuming a full sized fleet destroyer, Feb 1943, it may have been equipped with best gear.

Something else I recently learned from other modders and was shocked, but also makes sense is where you are on the map, as in latitude and longitude has a lot of effects on things. Weather, fog, sea state, thermoclines etc are linked to this and it does tie in with how the AI operates, interacts with various aspects.

Thinking about tough experiences with escorts when submerged, they seem to be most on top of things closer to equator you go and noticed further south, does not seem to be as many thermal layers.


When I was doing final testing for my mod, I started with a Gato USS Drum in new construction in 1942, played all through the war and survived (first time survived in anything "less" than a Balao the entire war in TMO, TMO gets very tough at the end for the boats that cannot dive as deep.

In 1943, like the real Drum, I patrolled out of Brisbane so all my patrols were below or at the equator and the enemy were really on top of things each time I attacked. I was coming home with serious damage often from depth charges, kept under for hours, if recall one attack was about 14 hours.

Then in 1944 after a refit period from December 1943 (representing the Drums real overhaul in early 1944, after her conning tower aft bulkhead was cracked during a intense depth charge attack south of caroline islands in November 1943, had to go to mare island and have a new conning tower installed) I was back to patrolling out of Pearl Harbor and operating well north, noticed plenty of thermal layers and in spite of it being 1944, with improved sensors and all, had nothing on what was encountering in 1943 out of Brisbane.

In TMO all escorts are set to veteran or high, mostly veteran and a few are set to elite here and there, so they are always skilled. I've made single missions in different areas and had similar experiences as to what I had with the DRUM. Now of course, there are a lot of variables involved, but there ya go. You are off Saipan, that is prime territory , ideal for enemy sonar etc.


Another interesting theory I have developed and am convinced of, is the sim models the different effects depth charges have at extreme depths. Now, unfortunately depth control below 600 ft is difficult, because UBI for whatever reason did not make work correctly. However, I have noticed when very deep in say a Balao or Tench, effects of depth charges are amplified at the deeper depths.

I went as far to make a mod where depth charges were all worth 100 points when exploded within 5 meters or 0 when outside five meters. At depths up to 600 feet, charge goes off close to Balao Class submarine, does damage, but not fatal.

Then I was at 650 feet and another time at 750 feet, both times they managed to get charges that close, critical damage, from same type of charge, same power, same distance (observed with external cam) . The one at 750 ft did hull damage, which of course caused loss of full hull integrity and was too deep, hull collapsed under pressure, boat dead. Same hull damage in balao at say 600 ft, did not cause hull collapse.

I had this happen in a career, which is what lead to the testing. I've tested this with so many variables to eliminate other causes. Also, my experiences in the campaign in various boats, various locations etc. Even current patrol, I was waiting out a escort in Sea of Okhotsk in August 1943 while I write this.
The depth charge attacks from a W-19 Class minesweeper, set to veteran (again like nearly all TMO escorts) in August 1943 in calm seas, has been lackluster, compared to same attack, same type, same time frame off Truk or Rabaul etc. I'm basically in the Artic and just can't seem to keep with me, boat is at 260 feet, been running 2.5-3 kts.



So it sounds like you ran into a veteran or elite crew, in what I am sure was calm seas, not attached to escort, likely with best sound/sonar gear free to hunt, and had a visual fix on your sub, a visual reference, in which to base its attack and pursuit in an area that generally has idea ocean conditions for their sound and active sonar to work. . Perfect storm of circumstances, one you likely won't get for a long time, if ever. Glad you survived.


Far as IJN radar. Well, in reality, no. The IJN radar was never on the level of US and its Allies, especially the surface search radar, especially when it pertains to detecting subs. Submarines of the day were relatively small surface targets, sit low in the water so not easy to detect. Numerous accounts in memoirs by US sub skippers, patrol reports, official histories etc of submarines making night surface attacks on convoys with radar equipped escorts. One critical factor was Japanese never had a PPI display...showing contacts position relative to that of the ship the radar was on, so it was they had the old A scope type of display, where they saw squiggly lines dancing around, so difficult to tell friendly from foe etc and it enabled US submarines, vs what the German U Boats and Japanese submarines dealt with from US and Allied radar, which had PPI displays and could not only detect submarines, but differentiate between then and friendly contacts due to PPI and IFF technology.


In the sim, stock game modeled the IJN horribly, made it Allied like in its effectiveness, I remember getting detected at 10 NM lol and escorts etc get way too early and every unit has it after certain point, which is void of reality. . Mods corrected, I believe a subsim member named Tater(if I recall) created the first fix I encountered, then I created one for TMO, it now simulates the IJN radar in manner more in line with history.


Anyways, did not mean to write a novel here but a lot of factors could have lead to your experience, it was definitely one which is rare, thanks for sharing.
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Old 11-08-21, 12:26 AM   #3
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Hi Bubblehead
Thank you so much for taking the time for such a detailed reply. Yes, the DD was on patrol and I was trying to sneak into Saipan harbour to do some harbour raiding to use up my remaining few torps before heading back to Pearl. Didn't get to see what class DD it was though.

Was not aware of how the game simulates noise levels, so your sharing that the best way to hide is beneath the thermal layer, silent running, <100 rpm, is very welcome.

Still, it was strange that the AI seemed to know exactly where I was at all times, he kept hovering around the orange marker in cam view, and when I was at all stop he literally did 8's around the marker. Didn't drop any depth charges though... or maybe he was out?

Coincidentally the sub that I'm captaining now is also the USS Drum.

Speaking of which - do the enemy DD's have a limited supply of depth charges?
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Old 11-08-21, 01:50 AM   #4
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Hi Bubblehead
Thank you so much for taking the time for such a detailed reply. Yes, the DD was on patrol and I was trying to sneak into Saipan harbour to do some harbour raiding to use up my remaining few torps before heading back to Pearl. Didn't get to see what class DD it was though.

Was not aware of how the game simulates noise levels, so your sharing that the best way to hide is beneath the thermal layer, silent running, <100 rpm, is very welcome.

Still, it was strange that the AI seemed to know exactly where I was at all times, he kept hovering around the orange marker in cam view, and when I was at all stop he literally did 8's around the marker. Didn't drop any depth charges though... or maybe he was out?

Coincidentally the sub that I'm captaining now is also the USS Drum.

Speaking of which - do the enemy DD's have a limited supply of depth charges?

No problem


Yes, RPM less than 100, ideally about 75-80 or ahead/back 1/3 when at silent running, sometimes I bump it up to 3 knots which is still under 100 RPM on fleetboats. Of course watch your instruments by the helm to make sure.

Speed bursts help also, when enemy is overhead, it masks your sound, so go ahead standard or full for 20-25 seconds during his pass, then slow to 1/3, the momentum will keep your boat moving at faster speed for some time. Use conservatively though, as can drain your battery fast. IF have the depth charge disturbance mod, your engines are masked by the noise of the depth charge explosions for a few moments.


Yes, they can run out of depth charges. The number they have varies from stock, to different mods. Thing is they are not done by x number of charges per ship, but its per launcher, so if ship has two DC racks and they are set to have 40 charges per rack, then they have 80 charges. Add in a Y gun or K Gun set to have 40 more etc, they have quite a few charges. That is pretty typical for a fleet type destroyer in TMO, sounds like a lot but they can burn through them quickly.


Then you have the dedicated escort vessels like the subchasers, esp later part of war, may have two racks with two, three, four, launchers, 50-80 charges each, then you put multiple escorts, they essentially have a unlimited number of depth charges. Something I plan to address in my next update for TMO is historically accurate number of depth charges and reload times for the launchers and racks.


Yes, it is possible the lone DD ran out of charges, but kept hunting and broadcasting your position., hoping for help from aircraft, other ships. I have experienced this before.


Far as how he stayed with you, as mentioned in my initial post, sounds like it was a number of factors, all working together.

Factors:

1. Your area, which as explained offers near ideal sonar conditions
2. Weather...i.e. calm seas.
3. Type of unit. Fleet type destroyer, so probably had best equipment for tracking.
4. Elite level crew, so sensitivity on all sensors heightened and operating at maximum proficiency. This means the thermal layer does not fool him the way it would a escort with lesser skills.

5.The visual fix he had on you when you surfaced, gave him a strong "scent" once you submerged again. Especially a big deal with dealing with skilled escorts.

6. This is a theory, I have not tested it fully, but 90 percent sure I am correct. In the sub files, there are electric engines, and "creep engines". Now, I asked and believe the creep engines, are a near silent version of the boats electric engines, that sub actually operates on when silent running is engaged which are utilized by your sub . These engines, listed in the files have hit points and thus can be damaged, like others. I believe when they are damaged, it simulates damage to your boats electric motors, and they are not as quiet as were prior to being damaged, which makes you easier to track. I have noticed heavy damage to a prop shaft seems to contribute in a similar manner as well. Now, the damage screen in game will show electric engine damage and have noticed that if my electrics get damaged, they have a easier time tracking me until repaired.

One patrol I lost two of my electric motors to close depth charge and others damage, the two damage were repaired but rest of patrol, even at depth, silent running, escorts seemed to track me. One I was approaching a convoy and normally can make high speed submerged runs at 300 feet to close the convoy track , slow and go to periscope depth to fire. Well, two attacks in a row, they heard me coming, even though was well below thermal layer, silent running and routinely use this method. So, it is possible, that aside from the other factors listed, your "invisible" silent drive was damaged and making noise. Your electrics may have been damaged as well. Unfortunately, all damage does not show up on the damage control screen. Theory for now, but would certainly explain it.


Adds up to a "perfect storm". Glad you survived. Curious, what was the max depth you went to ?



Nice! Drum, is my favorite WW II era fleetboat. I was raised about 60 miles (In Florida) from where she is a museum now, with the Battleship Alabama, in Mobile Bay, AL. When I was growing up, she was in the water moored behind the battleship. Unfortunately time and hurricanes necessitated she be removed from the water, so is landlocked now (Quite impressive how they did it actually. ) but still great to visit and have I visited the Drum more times than can count lol. When I was home visiting in August, went with a friend to visit, they were doing the living history drill that day, rather interesting. Man was it hot though lol esp down in the boat. Unfortunately, for first time ever, I was not able to go in the conning tower, apparently it has been closed since pandemic started.


Here is a link to Drum's official website, a lot of great information on the boat and photos. All of her war patrol reports are there as well.

https://www.drum228.org

Last edited by Bubblehead1980; 11-08-21 at 02:39 AM.
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Old 11-09-21, 05:08 PM   #5
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Wait until you get 6 vet Type C escorts on you making runs in pairs
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Old 11-09-21, 07:26 PM   #6
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Wait until you get 6 vet Type C escorts on you making runs in pairs

lol stuff nightmares are made of.
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Old 11-09-21, 10:24 PM   #7
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Drum, is my favorite WW II era fleetboat. I was raised about 60 miles (In Florida) from where she is a museum now, with the Battleship Alabama, in Mobile Bay, AL. Unfortunately, for first time ever, I was not able to go in the conning tower, apparently it has been closed since pandemic started.
securing the conning tower seems to be a common thing for the WWII submarine museums. i have access to the Cobia in WI and the Silversides in MI and neither allow access to the conning tower. ladder is chained.

i was up at the Silversides this past winter with a pal who is also ex-USN, i pulled a string or two and got access, but let me tell you, that is a young man's territory. i had difficulty not only climbing the ladder but coming down as well. and the space itself...gets smaller every time i visit. plus there is not a rounded edge anywhere up there.
and the ladder...gets taller and straighter every year.
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Old 11-10-21, 12:50 AM   #8
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securing the conning tower seems to be a common thing for the WWII submarine museums. i have access to the Cobia in WI and the Silversides in MI and neither allow access to the conning tower. ladder is chained.

i was up at the Silversides this past winter with a pal who is also ex-USN, i pulled a string or two and got access, but let me tell you, that is a young man's territory. i had difficulty not only climbing the ladder but coming down as well. and the space itself...gets smaller every time i visit. plus there is not a rounded edge anywhere up there.
and the ladder...gets taller and straighter every year.

I know and it is pretty ridiculous its common to restrict access, one of the most interesting and vital portions to visit.. Drum's conning tower was always accessible until COVID. My last visit there (and first since the pandemic) was a large number of people due to the living history drill that day.
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