In or under thermocline?

[shuggiebroon]

Hi guys.

I've been a fan of submarines for ages, done the tutorials and just started Delta Force.

I know that SSNs are much more noisy than the diesel subs I'm used to playing with in SH. In the tutorial it mentions that both enemy and ownship sensors are severely hampered when holding station within the boundaries of the level, as compared to floating just below it. I was wondering if anyone had played around and found exactly how much of a difference it makes?

My first attempt at the mission saw my SSN blown out of the water as soon as it peeked out from under the ice, obviously when you're essentially a floating nuclear reactor you can't just run deep and silent and expect not to be heard.

Thanks!

Hugh

[Cik]

it makes a pretty big difference

how much is hard to say exactly, but it can and will save your hide occasionally, the downside of course being that it obscures your ability to hear as well AFAIK.

[ultradave]

The key is not to run anything faster than 5 knots, maybe even 3 for older SSN's, if you suspect you are in danger of being noticed. You can go deep and faster to transit, where it is safe.

Also, it's not universally true that SSN's are much noisier than SSK's. Look at the data of newer versions of both kinds and you'll see they are pretty comparable. Older SSN's did not have nearly the amount of noise quieting technology as part of the design that new ones do. Of course, sonar then wasn't as good either. It's an arms race - the race for greater silence vs the ability to detect quieter things.

[Rory Noonan]

Hey shuggiebroon,

Something else to consider when choosing a depth is where you expect your threats to be, and whether you're hunting or hiding. In Delta Force you start under the ice, and your main threats are going to be other submarines (aircraft and surface ships pretty much can't get to you when you're under the ice), also there is lots of noise from the ice to hide in. I would recommend either in or above the layer.

Once you're out from the ice, your threats become more varied. Here it might be the best option to travel within the thermocline.

ultradave is right on the money with speed; you can get away with around 10 knots as a combat cruise (to coin a term), but for safety you really should stick to 5 knots and below for the best stealth.

[hellfish6]

So I've asked this question before as well, and didn't really get a satisfactory answer.

What exactly is going on when your sub is within the layer?

Not above or below it, but inside of it. My understanding of the layer is that it basically splits the passive acoustic detection capability into a top or bottom layer, and passive sensors are best able to detect other objects in the same layer as the sensor. But in many of my games, the layer is 100 feet thick, and I don't know what is going on with detection of objects inside of it. Is my sub better protected against things above and below the layer? Is it more vulnerable to other things within the layer?

Also, if you're operating just above or below a layer, your towed array is simulated to be operating on the other side of the layer. What about inside the layer - is your towed array floating above or below too?

[ExMachina]

ORIGINAL: hellfish6

So I've asked this question before as well, and didn't really get a satisfactory answer.

What exactly is going on when your sub is within the layer?

Also, if you're operating just above or below a layer, your towed array is simulated to be operating on the other side of the layer. What about inside the layer - is your towed array floating above or below too?

From the manual (pp. 132-133) the towed array "droops" behind the sub. So if your in the layer, your towed array would listen both within the layer and beneath that layer. To listen within the layer without emitting self noise into the layer, you need to position your sub just over it. And interestingly,according to the illustration anyway, in such a deployment the towed array can actually droop so far as to listen under the layer as well--not sure if this is 100% the case, or just the illustrator's attempt to show that it is at least possible...

EDIT: here's a quick image put together from the CMANO manual and a couple other sources

EDIT2: and the image is maybe not the most helpful as the layer in CMANO is (I presume) supposed to be the Seasonal Layer that lies between the Surface Layer and the Main Thermocline.

[shuggiebroon]

Thanks for the feedback!

Some very helpful replies, I'm really stoked to see how helpful the community here is. Looking forward to some experimentation today.

[hellfish6]

ORIGINAL: ExMachina

ORIGINAL: hellfish6

So I've asked this question before as well, and didn't really get a satisfactory answer.

What exactly is going on when your sub is within the layer?

Also, if you're operating just above or below a layer, your towed array is simulated to be operating on the other side of the layer. What about inside the layer - is your towed array floating above or below too?

From the manual (pp. 132-133) the towed array "droops" behind the sub. So if your in the layer, your towed array would listen both within the layer and beneath that layer. To listen within the layer without emitting self noise into the layer, you need to position your sub just over it. And interestingly,according to the illustration anyway, in such a deployment the towed array can actually droop so far as to listen under the layer as well--not sure if this is 100% the case, or just the illustrator's attempt to show that it is at least possible...

EDIT: here's a quick image put together from the CMANO manual and a couple other sources

EDIT2: and the image is maybe not the most helpful as the layer in CMANO is (I presume) supposed to be the Seasonal Layer that lies between the Surface Layer and the Main Thermocline.

That was helpful, but I'm still unsure of whether being inside the layer helps or not. It's useful to know the towed array works under the thermocline, but I'm still curious to know if being inside of the thermocline helps protect against a hunter in deep water or a surface ship pinging away.

[Puciek]

Being inside the layer helps against both, though it will also make you very much blind. It should give you sensible protection against both MF HF and LF sonars, but not as good as being in the appropriate side of the layer if possible (though it all depends on the weather, the strength of the layer, other noises, speed, profile etc).

[shuggiebroon]

So if one enemy unit is in the area, be on the opposite side, if two at different sides of the layer be in the middle and if a sun with a towed array is above the layer it can see into it?

[Puciek]

ORIGINAL: shuggiebroon

So if one enemy unit is in the area, be on the opposite side, if two at different sides of the layer be in the middle and if a sun with a towed array is above the layer it can see into it?

There is always a chance to be detected as a sub, no matter what. But if you are inside the layer, and moving at 2-3 kts then unless the enemy has sophisticated set of sonars the chances are very unlikely. It's really hard to put it to actual numbers, at least for me as I don't know them, but it comes with practice to know where to hide in what conditions, so just keep trying and see what works!

[Dimitris]

From the v1.0 manual, p.133:

In-layer: Similar to above, the towed array hangs below the layer but the counter-detection reduction is not as great (sound has to go through a lot less to reach an enemy sensor). Also the unpredictable mixup of warm and cold water at this depth range significantly reduces detection ranges against other subs also in the layer (think Mutara Nebula from Star Trek II).

[BrianinMinnie]

If your attempting to attack a enemy surface unit, and its database says it has a towed array, do you need to assume that its deployed below the layer, or does it depend on the depth of the Layer?

Let’s say the layer is 500 to 850, can the towed array drop below 850ft? and is it modeled to be always deployed by ASW Type unit?

Lastly against a modern ASW unit with a towed array, if you are on its bow, it seems very unlikely(generally) that one can creep to torpedo range before detection, what everybody’s preferred method of "not" dying!!

[Cik]

the best method of not dying to ASW specialized ships is to shoot them with surface units, or planes.

if you are forced to attack your direct counter, approach in the layer slow, get extremely close then launch and pray.

[Wolff117]

ORIGINAL: Puciek

Being inside the layer helps against both, though it will also make you very much blind. It should give you sensible protection against both MF HF and LF sonars, but not as good as being in the appropriate side of the layer if possible (though it all depends on the weather, the strength of the layer, other noises, speed, profile etc).

Just completed Delta Force yesterday. I raced at flank in the safe zone heading west. When I started south to the westernmost launch zone, I kept both subs in between the layers at 5kts. Didn't get detected at all and was able to launch. I just started playing this and I'm thinking I'll stay at just under the top layer every time and creep above for surface contacts and creep below for subsurface contacts.

[Dimitris]

ORIGINAL: BrianinMinnie
If your attempting to attack a enemy surface unit, and its database says it has a towed array, do you need to assume that its deployed below the layer, or does it depend on the depth of the Layer?

Yes, the assumption is that towed arrays and VDSs are always streamed under the layer. This is where they bring the greatest benefit.

[Herman_Hum]

ORIGINAL: Dimitris

ORIGINAL: BrianinMinnie
If your attempting to attack a enemy surface unit, and its database says it has a towed array, do you need to assume that its deployed below the layer, or does it depend on the depth of the Layer?

Yes, the assumption is that towed arrays and VDSs are always streamed under the layer. This is where they bring the greatest benefit.

Never thought about the option that surface ships could go sublayer with their towed… Playing Sonalyst simulations, surface assets only deployed shallow due to the limited wire. But it sounds very reasonable that surface ships with towed a´s would stream it down there.