Quiz time!
Look at the late war diagram again.

Sub A is at 200 meters. You know you can go to 260, and a bit beyond that. So If Sub A dives to 260 meters, Can you tell me approximately when the DD will lose active sonar contact?

Meh, ill just finish the thought then be misconscruted as patronizing. Its not my intetion, im only trying to illustrate this point the best i know how.

In the rough example of latewar sonar it has a maximum range of 2100 meters. By going to 260 meters by about 1200 meters, your out of this sonars cone. If you present a small profile, you may not get pinged at all. You have avoided this sonar.

Even if you didnt present a small profile and got pinged, your only going to get pinged for approximately 900 meters worth of travel. How long do you think it will take a 7 to 10 kt escort to travel 900 meters? Not very long. So by going deep, youve minimzed your exposure to being pinged.

@moomcat

Basically yearly war the sonar can look 200m deep, late war the sonar goes down to 300m deep. So early war you can go just below 200m and escape. Late war as the sonar looks deeper and you can only go maybe 260m max, the sonar will pick you up as it is looking past 260m....just where you are sitting. Not a cheat but if you mod you boat to go past 300m then this is a cheat and it does not make sense to mod you boat past 300m because he ingame DC just disappear.

I'd have to say we really don't know that. One thing ive always wanted to do, is take the sonar variables into a CAD program of sorts and draft out EXACTLY how deep the sonars are at a given range.

How deep an active sonar can really go, is dependant on it's maximum elevation and range. Early war sonar is an example of this.

But looking again at late war sonar (again, this images are NOT to scale, they are hand drawn to illustrate), by going deep, youve forced an approximate 1200 meter blind spot in the AI's active sonar. yes, he can ping you... at range, but up close, he can't. Thats when you have to be real quiet and wait him out. Because chances are if you do break free, and get a respectable distance from him (say 1200+ meters), if he happens to swing around in just the right way and catch you giving him a favorable aspect, he's liable to pick you up again, and your back to square one. So you always have to be mindful of your aspect to the escort. Break free, keep him at your stern turning from side to side a few degrees now and then to see what he's doing.

Hi All

Bit of a newbie here but I'd just like to say that I've not only found this thread really useful but incredibly interesting too!!! :up: :up: :up:

Well, if you can get Moby Dick to follow you, your safe at any depth. ;) I hear he loves to eat "tin cans" for a snack, any time of day. Plus they say he's really big so sonar will pick him up first, leaving you unmolested. ;)

Just picking. It's some of the best info and help on sonar we've had. :)

Funny you should say that because many a whale was bombed by planes who thought the poor buggers were subs.....just so happens they be venting on the surface like the u-boat!

Somebody call the SPCA on those bastages! :lol:

The problem is that there is no exact answer. Variations in tempurature and water movement can reduce the range drastically.

Here's a site showing how effective ranges are calculated when tracking schools of fish.

http://www.fao.org/docrep/003/X6602E/x6602e05.htm

You can actually hear your own fish if you duck into the sound room and put on ye old headphones (that is, go to the sound room and listen :p ).

Slowly manually move the bearing needle of the hydrophones and you can pick up the sounds of your torpedoes. You can even hear duds smack the sound of the hull; they made a low 'clunk' sound.

And yes, DDs and other escorts could hear your incoming fish, too.



*http://www.de220.com/Armament/Decoys/Decoys.htm

I'm no mathematician, but one can do a quick and dirty estimate.
As you could see from Ducimus drawing on the first page, the sonar "cone" forms essentially a right triangle. This diagram is nowhere near as nice as Ducimus drawing, but it gives the general idea:

1. The surface of the water (and the sonar beam angled at its highest elevation) forms the Adjacent side.
2. The length of the sonar beam angled at its lowest elevation forms the Hypotenuse.
3. The Angle is the maximum amount the sonar beam can be angled downward from the Destroyer.
4. The area within the triangle ( all of the //////// symbols ) is the sonar "cone", wherein the sub can be detected.
5. We want to know the length of the Opposite, which will tell us how deep the sonar cone goes (and how deep the sub can be detected) at its maximum depth.


---SURFACE OF WATER (THE ADJACENT)---DESTROYER
O ////////////////////////////////////////// ANGLE
P ////////////////////////////////////
P ///////////////////////////////
O /////////////////////////
S ////////////////// THE HYPOTENUSE
I ////////////
T //////
E //

According to the GWX files, an early war sonar has a range of about 1200 meters and can be angled down about 10 degrees. So our Hypotenuse is 1200 and our Angle is 10 degrees. Sin of 10 degrees is about .1736

Sin of the Angle = (Length of Opposite)/(Length of Hypotenuse) OR
Sin of the Angle * Length of Hypotenuse = Length of Opposite
.1736 * 1200 = 208.32 meters

So at its deepest point, the early war sonar only goes down about 208 meters (lets call it 200). The maximum depth decreases roughly linearly from 200 meters at the deepest point to 0 meters by the time it gets back to the destroyers position. So at the halfway point (about where the label HYPOTENUSE is in the diagram) the maximum depth is only about half of what it was, about 100 meters.

TRANSLATION:
An early war sonar can, theoretically, detect a sub at about the following depths:
At 1200 meters from the Destroyer - sub can be detected down to approx 200 meters.
At 900 meters from the Destroyer - approx 150 meters
At 600 meters from the Destroyer - approx 100 meters
At 300 meters from the Destroyer - approx 50 meters
At 0 meters from the Destroyer - 0 meters

You can plug other numbers into this:
A little better early war sonar has a range of 1500 meters, but still a 10 degree Angle.
So 1736*1500 = 260.4 meters maximum depth.

Late in the war things get much worse:
The second best late war sonar has a range of 2000 meters and an angle of 40 degrees, giving a depth of about 1285 meters(lets call it 1200). (IMPORTANT NOTE: Like many other elements in the game sonars do not detect below 300 meters. So it doesn't really see down to 1200 meters, but it is still useful for determing the depth at different points along the cone).

At 2000 meters from the Destroyer - sub can be detected down to 300 meters.
At 1000 meters from the Destroyer - 300 meters
At 400 meters from the Destroyer - 250 meters
At 250 meters from the Destroyer - 150 meters
At 0 meters from the Destroyer - 0 meters

The zone of safety shrinks (and then there's the BEST sonar with a 2200 meter range and an Angle of 65 degrees).

IMPORTANT NOTES:
1. Keep in mind, that even if my figures are correct, they represent THEORETICAL, absolute maximums under perfect conditions (Sonar is able to get maximum range, no interference etc.). I assume the game is taking into account things which will reduce range (and hence depth) and other hindrances. Not to mention you are doing everything not to get pinged (reducing target aspect etc.).
2. The two late war sonars listed above are the BEST in the game (so constitute a worse case scenario). Some other late war sonars still have only a 10 degree angle.
3. Note that in late war not every escort gets the latest and greatest sonar equipment. Some get less capable late war sonars, other still carry earlier equipment.
4. It is possible that SH3 may use a simplified model. For instance, instead of a continuously decreasing maximum depth, it may only change the maximum depth every X meters or every X% of the range, so the maximum depth becomes a series of block steps rather than a smooth angle. Haven't run any tests to see if this is so.

IMPORTANT DISCLAIMER
Obviously there are other factors in the game (and math) that come into this, so this just gives a quick and dirty, THEORETICAL and VERY GENERAL approximation. Not to mention my own complete incompetence when it comes to math does not guarantee that there isn't a mistake in here.

Thats an awesome post Steppenwolf! Your skillls in mathemtics dwarf my own. I can balance my budget, thats about it. :lol:

Edit: one thing that troubles me though is your approximations to how deep late war sonar can go vs the distance from the destroyer. (i know you said this was quick and dirty approximations). The reason is, ive found that the AI tends to ping me from when its say, 700ish meters or more ( best guess) away from me. Inside of that distance, i dont get pinged very often. A destroyer typicaly has to make a wide circle to reaquire me.

Edit: A slight DUH here. There was an error in that last chart, which I have now edited. I believe the two guesses below are still correct.

Well, did say it was quick and dirty:) My best guesses are these:

1. Keep in mind, that even if my figures are correct, they represent absolute maximums under perfect conditions (Sonar is able to get maximum range, no interference etc.). I assume the game is taking into account things which will reduce range (and hence depth) and other hindrances. Not to mention you are doing everything not to get pinged (reducing target aspect etc.).

2. Although the very best of the late war sonars (the two I listed above are the BEST in the game), have the capabilities mentioned above, not all ships in late war are equipped with them. Some of even the later Sonar models are still limited to 10 degree Angles. Also, there are still a lot of ships in late war that are using the older equipment and hence cannot ping you at that depth.

DISCLAIMER:
I am no expert on sonar operations, so this is just a guess and you can take with a grain of salt.:)

Unfortunatly, the AI sonar in SH3 is much like a flashlight, it's shaped how it is, and its either on or off. It doesnt do sweeping motions. Thats my understanding of it anyway.

If you want an illustration in motion, target a destroyer in a singleplayer mission with the auto TDC enabled. You'll see a graphical represenation of his sensors on the map, and you'll physically see the sonar cone's width and shape from a top down view.

That also shows you, I believe, the passive hydrophone detection areas too.