A curious thought on DW passive sonar detection range

[Castout]

Yesterday when I played SC campaign in DW I noticed something that intrigue me.
My platform was the Akula II Vepr and I played with LWAMI 3.08 mod installed.

With regard to passive sonar detection range I found that I was just able to detect an Arleigh Burke DDG travelling at 9-11 knots at about 3-3.5 nmi range which is roughly less than 7km away. And it only showed in the narrowband.

Now this is what intrigue me as when I played Silent Hunter III I found that I was able to detect slow moving merchant(5 knots speed) at about 10 km or more.

I know that with LWAMI installed I should have my passive sonar detection range enhanced and that DW is set in modern times when even the military surface ships are designed with noise dampening in mind hence they are more silent than merchant ships but my detection range for merchant ships is also not that great having able to detect them only at mostly 8 nmi(that is les than 12km) to have them on the broadband contact which enables the DEMON calculation.

I have also heard that DW only model direct sound contact but
Are these detection ranges not ridiculously too short for modern top of the line submarine?:hmm:

[To be]

Were you above or below the layer?

[Dr.Sid]

Here are some measurements I made. It is NOT detection range, but it shows pretty well how sound modelling is done in DW.

http://www.subsim.com/radioroom/showthread.php?t=117814

Edit: All hail new 'Ace of the deep, 1000 posts (and back safely)'

[sonar732]

When you post questions like those, it helps to provide us with information.

1. SSP
2. Where you were in relation to the world. ie...deep water, shallows, etc.

[Castout]

There was no thermal layer as I was in a relatively shallow water with the bottom at around 50-100m.

My depth ranged from periscope depth to 60 m.

[SeaQueen]

Originally Posted by Castout

I have also heard that DW only model direct sound contact but
Are these detection ranges not ridiculously too short for modern top of the line submarine?:hmm:

The answer, ultimately, is that it depends. There are times a modern submarine might not detect something until it is a couple miles a away, there are times a modern submarine might detect something hundreds of miles away. You have to understand that the only major difference between an SQS-53 (today's high-end surface ship sonar) and an SQS-26 (shortly after WWII technology) was the composition of the sonar dome. The biggest advances have been in signal processing but even then, what the technological advances bought you, in practice was not always clear.

One of my pet peeves in submarine simulations is that people are always whining about what they think sonar ranges ought to be, and everyone mods things to reflect what they think everything ought to be in the abscene of any useful evidence or experience regarding actual sonar performance.

The truth is that sonar ranges are highly variable things that depend greatly on the minutiae of everything from whether the operator is tired or inexperienced, to small variations in the properties of the water column. Under some set of circumstances, you will can experience any sonar range.

In this light, the imporant thing from the perspective of a wargamer is not whether the range in game X is Y, and whether it is real or not, because basically any range is realistic for any sonars. Rather, the important thing is the tactics you develop to exploit or deal with the detection range you happen to get.

That's what real submariners do, and the point of wargames is to give you a taste of that. Each day, they use sophisticated computer models of sound in the ocean to attempt to get some feel for what it might be, and even that is subject to great uncertainty. There is no single answer to point to and say, "Ah Ha! that's the range for sonar X." I mean... in the sonar equation, the one of the most important terms is the recognition differential, which is simply to reflect operator skill and experience. I have read at least three papers arguing about how to actually compute it and they all have different opinions. I've also found inconsistences in identical conditions between pieces of software used to compute sonar ranges. Nobody has the answer. Sometimes they're big inconsistences. I remember one time I found a model that predicted that one got a convergence zone detection and in another they didn't. That's the difference between detecting at 35 miles and detecting at maybe 10 (on a good day).

Nobody knows how far their sonar can really see on any given day, at any given time. At best they can make educated guesses, which are frequently wrong.

There is no reason for submarine simulations to be consistent with one another. There is no reason for submarine simulations to choose any particular sonar range over any other. They're all correct.

I almost think the best way to handle things is to completely take any pretention of attempting to model underwater sound in the ocean out of the simulation and just draw it at random from some distribution. You'd probably end up with a result that was at least as correct as any painstakingly accurate acoustic model.

[Castout]

Hmm you have a point SeaQueen but I'm rather upset that I'm commanding a supposedly top of the line sub that could barely detect an enemy surface ship only at less than 4nm. I'm already blind now I'm almost deaf too.

Considering that in SH3 I could detect a merchant ship at much longer distance...

I know that I probably should treat 2 sims seperately but I just can't help myself comparing one with the other just to use one as a reference for the other.

But I do not mean to whine I just want a total revamp of the sonar detection range.....kidding

[sonar732]

Originally Posted by SeaQueen

The answer, ultimately, is that it depends. There are times a modern submarine might not detect something until it is a couple miles a away, there are times a modern submarine might detect something hundreds of miles away. You have to understand that the only major difference between an SQS-53 (today's high-end surface ship sonar) and an SQS-26 (shortly after WWII technology) was the composition of the sonar dome. The biggest advances have been in signal processing but even then, what the technological advances bought you, in practice was not always clear.

One of my pet peeves in submarine simulations is that people are always whining about what they think sonar ranges ought to be, and everyone mods things to reflect what they think everything ought to be in the abscene of any useful evidence or experience regarding actual sonar performance.

The truth is that sonar ranges are highly variable things that depend greatly on the minutiae of everything from whether the operator is tired or inexperienced, to small variations in the properties of the water column. Under some set of circumstances, you will can experience any sonar range.

In this light, the imporant thing from the perspective of a wargamer is not whether the range in game X is Y, and whether it is real or not, because basically any range is realistic for any sonars. Rather, the important thing is the tactics you develop to exploit or deal with the detection range you happen to get.

That's what real submariners do, and the point of wargames is to give you a taste of that. Each day, they use sophisticated computer models of sound in the ocean to attempt to get some feel for what it might be, and even that is subject to great uncertainty. There is no single answer to point to and say, "Ah Ha! that's the range for sonar X." I mean... in the sonar equation, the one of the most important terms is the recognition differential, which is simply to reflect operator skill and experience. I have read at least three papers arguing about how to actually compute it and they all have different opinions. I've also found inconsistences in identical conditions between pieces of software used to compute sonar ranges. Nobody has the answer. Sometimes they're big inconsistences. I remember one time I found a model that predicted that one got a convergence zone detection and in another they didn't. That's the difference between detecting at 35 miles and detecting at maybe 10 (on a good day).

Nobody knows how far their sonar can really see on any given day, at any given time. At best they can make educated guesses, which are frequently wrong.

There is no reason for submarine simulations to be consistent with one another. There is no reason for submarine simulations to choose any particular sonar range over any other. They're all correct.

I almost think the best way to handle things is to completely take any pretention of attempting to model underwater sound in the ocean out of the simulation and just draw it at random from some distribution. You'd probably end up with a result that was at least as correct as any painstakingly accurate acoustic model.

:hmm::hmm:

[sonar732]

Originally Posted by Castout

There was no thermal layer as I was in a relatively shallow water with the bottom at around 50-100m.

My depth ranged from periscope depth to 60 m.

In another words...your sonar conditions SUCKED!

[Molon Labe]

Those detection ranges look about right for bottom limited in mud/sand, especially from PD. It's not just the Akula, all sonars are going to work like **** in ****ty acoustic conditions!

[Dr.Sid]

From my experience:

- AFAIK, in DW, shallow water does not affect sound travel, except for terrain blocking the signal. But I guess it should block everything or nothing, it should not weaken the signal.
- Sea state on the other hand does lower sonar performance significantly. So what was your sea state ?
- Burke at 10kts, at 3nm should be nice and bright, impossible to miss (based on my DW experience alone). There IS something fishy here, that is NOT normal. What array did you use ? What speed were you going ? All arrays are easy to washout with excessive speed. In shallow water towed array is easy to get draged on the bottom. Please post screenshots from that situation, from map and from sonar station.

[DrMilton]

Comparing SH3 with DW is not the right approach here. SH3's acoustic model is not so accurately designed as to include all the acoustic parameters that DW does. The Uboot's hydrophones will usually pick up contacts near their nominal "range" no matter what. Now, as a SH3 enthousiast myself I would gladly trade some of the aesthetic elements for a more accurate sonar environment and thus make hydrophone usage more fun. This is not to say that SH3 model is completely "flat" but it could sure be improved in terms of sound propagetion depending on SSP, sea state, ownship depth etc. Supposedly being near the surface makes it harder to hear contacts but I have yet to confirm that during play (although I try to convince myself that I have). Of course DW could in turn be improved in terms of ship's behavior on rough seas, masts that are invisible to the enemy etc.

Although both are great games some of their aspects cannot be directly compared so don't feel bad about not getting in DW what you would expect from SH3. Look at it this way: if you manage to master sonar in DW then no british ship will stand a chance against your uboot

[SeaQueen]

Originally Posted by Castout

Hmm you have a point SeaQueen but I'm rather upset that I'm commanding a supposedly top of the line sub that could barely detect an enemy surface ship only at less than 4nm. I'm already blind now I'm almost deaf too.

Welcome to reality. Use your periscope, radar and ESM. That's part of why they're there.

[SeaQueen]

You really don't need a acoustic model to do WWII submarines because they were mostly relying on direct path energy to get their detections.

You need to know what's going on when you're dealing with bottom bounces, convergence zones and what not.

[DrMilton]

Originally Posted by SeaQueen

You really don't need a acoustic model to do WWII submarines because they were mostly relying on direct path energy to get their detections.

I presume that audible freqs behave the same as the rest of the freqs a modern sonar can pick up. So, if sound can't reach a modern sensor then it shouldn't reach the sonarman's ears too (...right?). A more accurate model would prevent this.

You need to know what's going on when you're dealing with bottom bounces, convergence zones and what not.

I'm not sure what you mean by that.