RFB - Avoiding detection

[Althar93]

Hey all,

I have started playing SHIV again after a few busy weeks, and most importantly RFB, and I am loving it. Following my current patrol, I have a couple of questions on detection. Although I have no problems with shooting torpedoes and sailing off when the party is over, I am struggling a bit to intercept convoys properly.

I am either too accurate, or very (un)lucky, but I always end up spot on the convoy's trajectory when attempting to ambush it. The consequence is that it then always seems to be sailing directly towards my position. Being on their path, the escorts always starts pinging and detects me before I can even start identifying my targets. Just recently, the same situation occured, and I ended up with 7 destroyers on top of me : fortunately, their large number prevented them from maneuvering and bombing me efficiently, as I could admire on the surface, and they eventually left :salute:.

Now I have read articles about the detection devices used, and Ducimus' article about the "uber" AI demystified", and think I am pretty comfortable with "evading" (generally :D), my problem is avoiding detection in the first place.

Even if I am sitting like a rock in front of an unsuspecting convoy, they always end up seeing me and raising the alarm miles away.

1 - What am I doing wrong ? Should I try to intercept the convoy making sure I am parallel to their trajectory, or should I try to intercept it on the outside?

2 - What other parameters/actions might affect the likelihood of the escorts detecting me in the first place ( profile parallel/perpendicular, silent running on/off, etc)?

3 - Can checking for the depth under the keel result in detection (I do not know the specifics, but I am guessing the signal just bounces back up to the submarine, so I was wondering whether it is the same in RFB : I just want to make sure)?

Thanks in advance for your help :DL!!!

Happy hunting!

[Diopos]

Assuming you're in a favorable position in front of the convoy and that it doesn't change course try the "deep" approach. Under the thermal layer, possibly near "test depth" or even deeper. silent running and low speed. Monitor the situation via passive sonar. Regardless of how the game implements it, I never use active sonar (including depth-under-keel measurements) in the presence of warships.

Now the key to navigate via passive sonar is your ability to "visualize" the situation on top. Recently I was experimenting with attacking convoys from "within". This essentially meaning try to keep the "center" of the convoy at 0° relative bearing (RB) while remaining on its path.

At far distance you may have a signal with a spread of ~5-10° (centered at ~ 0° RB of course). You may have some specific "target type" resolution ie DDs (high speed screws) or merchies (low speed screws).

At medium distance the spread has widened and you can resolve flanking DDs/Escorts and probably the leading escort. Start tracking the flanking DDs and observe if there is a high speed screw signal "atop" of the low speed screws. Note if it is shifting from left to right,this indicates a leading DD doing "sweeps" in front of the convoy. Try to keep the "center" of the low speed screws at 0° RB.

At close distance flanking DDs/Escorts at 270-310°/90-50° RBs, Leading Escort somewhere at your flank or rear quadrant, low speed screws spreading from 330° to 30° RB. Your sonar man will be probably identifying closest contact at Short Range.

At this stage you'll be considering the details of ascending to periscope depth and turning to get as "vertical" as possible relative to the convoy course. But as far as the "final approach" part of your attack, you can already consider yourself IN the convoy.

At medium and close range you may need to conduct maneuvers to minimize your "aspect" relative to the DDs/Escorts.

This method works well for stock "dumb" and "straight running" convoys. But what I am trying to emphasize here is not the method itself but the "stay deep", monitor via hydrophones but above all try to "reconstruct" the situation on the surface aspect of it.

Remember that regardless of what "final approach" tactic you may choose your success will very much depend on the data you have collected during the "shadowing" of the convoy. Convoy course, speed even zig-zag patterns can be collected at this stage. Then YOU decide time, location and mode of attack. YOU have the initiative.

[Althar93]

Hi again,

Thanks a lot for your help, I put the theory into practice, and managed to intercept a convoy undetected and sink a few ships : a cruiser/carrier (I'm not too good at recognizing them :damn:), two tankers, and hitting a passenger ship (surprised it could still move at top speed with that gaping hole in the bows).

Fortunately for me, the convoy was in a narrow line formation, with the forward scout too far ahead to see me, and the rest of the escort miles away at the rear. Following your tips, I was able to alternate between forward and aft tubes, diving underneath the convoy and following it for a good hour, surfacing every time I was ready to fire again, and using the hydrophone to make sure the rear escort was still out of reach.

Finally, I was allowed a very useless and tedious counter attack, with very inaccurate depth charging, thanks to the fact they had no idea whatsoever where I was :rock:. Thanks again :D !!

I just have a couple more questions you might be able to help me with :salute: :

-How do you determine whether a ping is a "found" or "search" ? For the moment, I have been relying on the intensity, and it seems to work, however I am unsure whether I can really consider myself safe if I only hear light pinging (low frequency and volume). I am asking this, because in that situation, they tend to detect me again eventually, even if I play dead. Would they still get some kind of feedback in the case of a "small" ping, explaining why they end up finding me?

-Also, when dealing with multiple destroyers, do they interact with each ,using their sensors triangulate my position, or do they simply look for me independantly ? I would have thought the first one, but they seem quite stupid at times and are not able to do anything. It is probably because I'm at the beginning of the war, but I can simply dive to 250-300 feet in my Porpoise, and have them pinging me like crazy at a distance, without being able to take an accurate shot once they go for a run...

[BillBam]

A ping means they have found you, however a light ping means they do not have a good fix and you can still evade, heavy ping "dive dive" hahaha.

They definitely work as a group. Generally one will always be listening with passive will the others ping. One part about the game that is not very realistic is that the ones listening can still hear you even when DC are exploding so you are not safe even when there is a ton of noice in the water.

[Admiral8Q]

1 - What am I doing wrong ? Should I try to intercept the convoy making sure I am parallel to their trajectory, or should I try to intercept it on the outside?

2 - What other parameters/actions might affect the likelihood of the escorts detecting me in the first place ( profile parallel/perpendicular, silent running on/off, etc)?

3 - Can checking for the depth under the keel result in detection (I do not know the specifics, but I am guessing the signal just bounces back up to the submarine, so I was wondering whether it is the same in RFB : I just want to make sure)?


1- The other guys answered that! Go deep. Weather is an important factor too. The worse the weather is, the better it is for you!:03:

2- You basicaly answered your own question there. Yes profile parallel/perpendicular etc has an effect on being detected. In TMO you get uber destroyers so it's best to hide early! :woot:

3- I'm not sure about RFB, but in stock and TMO a "ping" to get depth will alert any destroyers to your where abouts. I don't recommend it.:hmmm:

[I'm goin' down]

Assuming you're in a favorable position in front of the convoy and that it doesn't change course try the "deep" approach. Under the thermal layer, possibly near "test depth" or even deeper. silent running and low speed. Monitor the situation via passive sonar. Regardless of how the game implements it, I never use active sonar (including depth-under-keel measurements) in the presence of warships.

Now the key to navigate via passive sonar is your ability to "visualize" the situation on top. Recently I was experimenting with attacking convoys from "within". This essentially meaning try to keep the "center" of the convoy at 0° relative bearing (RB) while remaining on its path.

At far distance you may have a signal with a spread of ~5-10° (centered at ~ 0° RB of course). You may have some specific "target type" resolution ie DDs (high speed screws) or merchies (low speed screws).

At medium distance the spread has widened and you can resolve flanking DDs/Escorts and probably the leading escort. Start tracking the flanking DDs and observe if there is a high speed screw signal "atop" of the low speed screws. Note if it is shifting from left to right,this indicates a leading DD doing "sweeps" in front of the convoy. Try to keep the "center" of the low speed screws at 0° RB.

At close distance flanking DDs/Escorts at 270-310°/90-50° RBs, Leading Escort somewhere at your flank or rear quadrant, low speed screws spreading from 330° to 30° RB. Your sonar man will be probably identifying closest contact at Short Range.

At this stage you'll be considering the details of ascending to periscope depth and turning to get as "vertical" as possible relative to the convoy course. But as far as the "final approach" part of your attack, you can already consider yourself IN the convoy.

At medium and close range you may need to conduct maneuvers to minimize your "aspect" relative to the DDs/Escorts.

This method works well for stock "dumb" and "straight running" convoys. But what I am trying to emphasize here is not the method itself but the "stay deep", monitor via hydrophones but above all try to "reconstruct" the situation on the surface aspect of it.

Remember that regardless of what "final approach" tactic you may choose your success will very much depend on the data you have collected during the "shadowing" of the convoy. Convoy course, speed even zig-zag patterns can be collected at this stage. Then YOU decide time, location and mode of attack. YOU have the initiative.

The above only works if the sonar man has not turned off his hearing aids!

[Diopos]

Of course you do the sonar work. No way you can do this kind of approach with "standard" sonar reports.

[Diopos]

Pings do not mean that you are detected necessarily.
An increase in ping pulses mean trouble.
Increased ping pulses with a secondary lower volume "echo-ping" means you are "fixed".

At least that is how I see it!

.

[BillBam]

Pings do not mean that toy are detected necessarily.
An increase in ping pulses mean trouble.
Increased ping pulses with a secondary lower volume "echo-ping" means you are "fixed".

At least that is how I see it!

.

It is my understanding that "in-game" you hear pings they are getting a return off you, but if it is light they do not have you good lock on you.

[Red Devil]

I too like my convoys to come to me and get into a handy position, about 20 - 30 deg off to one side, and hopefully within 2000, go down to 200 and switch off and go silent. As the lead escort is passing, normally to one side, I then order PD and later go 1/3 and begin attack. Only a couple of times have I been detected in many many convoy attacks like this.

[Admiral8Q]

It is my understanding that "in-game" you hear pings they are getting a return off you, but if it is light they do not have you good lock on you.
If the pings are getting more frequent after each one then, yes, they have you! :o

[Red Devil]

I think that the subject of detection should be addressed in the mods. I am going to strip game down and reinstall and start again as my detection rate has gone to 100% and I never even sneezed - must be some sort of bug?

[Zel]

As soon as you hear a ping, it means you're detected. For this to occur, you must be within his sonar cone for a specified period of time, while presenting enough surface (sim.cfg). When you hear the first ping, the convoy will start zig-zagging.

Heavy pinging means a destroyer is close to you.

If you're below the thermal layer, you're much harder to detect with sonar. Also, if you're shallow enough, they can't ping you at all (decks awash).

The early war DD's have short range on their sonar. as the war progresses, the range of their sonar is increased.

[Red Devil]

Actually not quite right. When I was in Rabaul inlet, to take photo's of two carriers, I was getting hit, minus pings, very easily, down below 250 and on silent and no forward motion. The 'noise' from my sub was quite bad even in that silent state. I anticipated a program error and completely uninstalled SH4 after removing TMO18 but saving saves.

I reinstalled it not too long ago and ran Balao save into Rabual again, but this time without the compatibility on Vista or XP (cant recall right now) and I managed to sit on the bottom with destroyers passing nearby without detection and completed my mission getting to within 7000 yards of the carriers. I then reversed a few hundred yards on dead slow and turned boat to port then forward and hard starboard and was nearly safe when a DD pinged me and came in, so I went down to the bottom again and sat silent and he ran past, so I went back to 1/3 periscope depth and got him to 2 rear torps, then suffaced and ran like hell at flank. Shore batteries were having pot shots at me but only minor damage. I escaped .......

[Zel]

Interesting story! Sitting on the bottom usually doesn't work for me, so i try to move away slowly.

Perhaps he detected you initially, but later lost detection?

Going deeper always helps, not just because of the layer, but also you can get under the sonar cone.

[Red Devil]

depending on location the bottom is 300+, moving nearer to the carriers the bottom shallows to 200 - 250 then above 200. I was initially in the central band when detected but luckily for me going at speed and to PD seems to have worked. I managed to pot him and run.:arrgh!:

But to get back to the main point, maybe compatibility knockback to XP caused a 'fault' and gave the destroyers more capability of finding me, simply do not know. I did it on Win 7 and got away.

[Alpha Von Burg]

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you could try using bold 1 decoys. i have never used one before.. yet...
however by the way the game discribes it, " it releases a chemical (metalic substance ) which creates a sort of false image for about 3-5 minutes giving the u-boat time to slowly slip away "

like I said, I have not used it yet, so im not intierly sure how effective this really is.

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Or you could try evading the destroyers till they get tierd of hunting you, don't know why but it works for me,

change depth from time to time, turn hard to port or starboard just make sure the destroyer is at around 90 degrees on your port or starboard to keep minmum damage from depth-charges when the destroyers pass over you. and stay quiet by keeping the speed low and only increase speed when thier on top of you. avoid staying at a curtain depth, trust me they seem to be able to set depth-charges to det. at curtain depths.

this dosen't exactly help avod detection because when your in front of them and your moving they'll find you, you can move whe your behind them, but again, quietly.

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note its harder to escape destroyers which aren't on escort duity.
i hope this can come in handy

patiance and memory, is the key...
-Von Burg :salute:

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ps. im new and im just tring out the signiture thing...
i hope you lot don't mind if i took the space...

[Sailor Steve]

As soon as you hear a ping, it means you're detected.
No. A ping only means they're using active sonar, and they're close enough for you to hear it. As someone said earlier, if the pings start increasing in frequency then they're on to you. When you hear the pings it's a good time to get end-on to them to lower your profile. Also a good time to go silent. If one is pinging another is listening.

[Althar93]

A lot of usefull information, did not expect that many replies, thanks a lot guys :up: !!

About the search pattern of escort destroyers, has anyone experienced this : after getting bored, the destroyers usually leave at top speed to rejoin their convoy, but most of the times, I see the last destroyer acting funny.

He seems to be following his friends, but at funny speeds. He accelerates for a second (litterally) and then stops and slowly drifts forward. This behaviour can be observed for hours, and quite frankly, makes it extremely easy to go back and shoot down the idle target at close range ( since the sub is already in the "deaf" area of the destroyer ).

Is he trying to listen? Or is this just a bug?

[Red Devil]

I see this loads of times and assume its 'normal'. He is listening but keeps unpredictable movements going to foil any attempt maybe to torp him. Only today, caught a convoy in the Carolinas and the escorts were looking at the wrong side of convoy and I had a turkey shoot. 5 sunk, 3 damaged and 1 escort sunk, who was 'listening' and dud not move about 2500 yards away. I didnt aim actually AT him, but a freighter that turned!!! :yeah: Ran out of torps so broke off.

[Sailor Steve]

I've had destoyers hound me and 'tag-team' me, but I've also heard them pinging while heading in the wrong direction and even drop depth charges way off the mark. It's nicely random, and feels fairly real.

[I'm goin' down]

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you could try using bold 1 decoys. i have never used one before.. yet...
however by the way the game discribes it, " it releases a chemical (metalic substance ) which creates a sort of false image for about 3-5 minutes giving the u-boat time to slowly slip away "

Incidentally, in TMO1.9, Ducimus, its modder, disabled decoys. He said they were not realistic, etc.

[Diopos]

...
It's nicely random, and feels fairly real.

Uhmm ... we are not talking about my life, are we ??!


:DL


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