sonar performance

[raduz]

This is what I found on wikipedia:
http://en.wikipedia.org/wiki/Sonar

"Sound waves that are radiated down into the ocean bend back up to the surface in great arcs due to the increasing pressure (and hence sound speed) with depth. The ocean must be at least 6000 feet (1850 meters) deep, or the sound waves will echo off the bottom instead of refracting back upwards, and the loss at the bottom reduces performance."

Then why the DDs were able to ping the subs even in shallows water?

[switch.dota]

Active sonar *should* be less effective at finding a sub in shallow water, especially when the sub is close to the bottom. This is not modelled into the game, however.

[John Channing]

The operative word there is "reduces"... not eliminates!

JCC

[SteamWake]

The subs of that era did not have sound absorbing materials applied to their hull. Also they had plenty of 'right angles'. Also they (subs) were typically suspended above the ocean floor. They made a much better uhhhh sound bouncer than the ocean floor.

[Sailor Steve]

First of all, that portion of the article seems to me to be talking about using sonar to map the ocean bottom. Spotting an underwater object that is much closer to the transponder than the ocean bottom will obtain a echo sooner. Also, anti-submarine sonar never pointed anywhere near straight down. Spotting a submarine in shallow water was more difficult, but not by much. Most difficult was spotting a sub actually lying on the bottom - it was easy to confuse other objects with the intended target.

This might be of some help:
http://www.de220.com/Electronics/Sonar/Sonar%20Photos/Sonar%20Patterns.jpg

[SteamWake]

Most difficult was spotting a sub actually lying on the bottom - it was easy to confuse other objects with the intended target.


Unfortunatly this does not seem to be modeled in the game. Trust me Ive tried.

[Sailor Steve]

Most difficult was spotting a sub actually lying on the bottom - it was easy to confuse other objects with the intended target.


Unfortunatly this does not seem to be modeled in the game. Trust me Ive tried.
I agree. It worked quite well in Aces Of the Deep. Unfortunately so did getting stuck in the mud. I died that way once.:dead:

[Peto]

LOL Sailor Steve! That happened to me more than once with me banging on the dive/rise commands (which did work once in a while). I wonder why no one has incorporated some of the basic things that were in AOD--escorts doing search patterns, lying in wait for you to surface etc.

AOD was a great sim in many ways.

Cheers!

Peto

[WernerSobe]

well unless a sub is lying on the ground an expirienced sonar operator should be able to separete the ground echo from sub bounce.

ground echo sounds different to returns from a sub and you know the first echo is the sub, the second is the ground. I think they could even setup the filters to reduce the ground echo amplitude.

But anyway the ground echo is not modeled in game.

[John Channing]

LOL Sailor Steve! That happened to me more than once with me banging on the dive/rise commands (which did work once in a while). I wonder why no one has incorporated some of the basic things that were in AOD--escorts doing search patterns, lying in wait for you to surface etc.

AOD was a great sim in many ways.

Cheers!

Peto

Not sure what you mean there. If you don't think the escorts in SH4 lie in wait for you then you have been very lucky.

On several occasions I have seen one escort stay behind after the others rejoin a convoy and just sit there at all stop... waiting for you to surface. If you out wait him he will then search on both sides of the convoy track all the way back until he rejoins the formation.

JCC

[SteamWake]

LOL Sailor Steve! That happened to me more than once with me banging on the dive/rise commands (which did work once in a while). I wonder why no one has incorporated some of the basic things that were in AOD--escorts doing search patterns, lying in wait for you to surface etc.

AOD was a great sim in many ways.

Cheers!

Peto

Not sure what you mean there. If you don't think the escorts in SH4 lie in wait for you then you have been very lucky.

On several occasions I have seen one escort stay behind after the others rejoin a convoy and just sit there at all stop... waiting for you to surface. If you out wait him he will then search on both sides of the convoy track all the way back until he rejoins the formation.

JCC

Ive also witnessed them working in teams with one darting about pinging away and dropping the occasional can while the other drifts and listens.

[Sailor Steve]

On several occasions I have seen one escort stay behind after the others rejoin a convoy and just sit there at all stop... waiting for you to surface. If you out wait him he will then search on both sides of the convoy track all the way back until he rejoins the formation.

JCC

Ive also witnessed them working in teams with one darting about pinging away and dropping the occasional can while the other drifts and listens.
They did the 'tag team' thing in SH3 too. The one searching the sides on his way back sounds cool.

[Peto]

I agree that they're there BUT!!!---I always know that they're there. In RL (and AOD) they would lie quiet. You'd think they were gone but they would catch you when you came up. In SH4 (which I love playing btw--great sim) I can evade them as long as I know where they are.

This is better and they're more persistant since 1.3 patch though and I think it's a great improvement.

Cheers!

[SteamWake]

I agree that they're there BUT!!!---I always know that they're there. In RL (and AOD) they would lie quiet. You'd think they were gone but they would catch you when you came up. In SH4 (which I love playing btw--great sim) I can evade them as long as I know where they are.

This is better and they're more persistant since 1.3 patch though and I think it's a great improvement.

Cheers!

If a ship is sitting 'up there' at a dead stop how do you know hes still up there short of using the exterior cam ?

Only reasoning I can think of is you have his last known position and did not 'hear' him move off so you can assume he is still there.

[John Channing]

Since 1.03 and TM 1.03 I often lose sonar contacts when they shut down (and even when they don't). This is one of the best features as far as I am concerned as it introduces an element on incertainty.

Now if only I could resist the urge to F12 to take a peek :D .

JCC

[Peto]

there was no exterior cam that I remember in AOD (and I seldom use it it SH4) so the whole purpose of lying silently was to surprise you. And they often did. It was hard to discern if one of the escorts had gone quiet or simply left. With the earlier subsims like AOD you didn'y have the kind of system control we now enjoy in SH4.

The main thing I wish was an option for SH3 and SH4 is realistic escort behavior when they lose a contact. Ther were standard patterns escorts would ue to re-establish contact. In the sims they just flounder around. A spiral or ladder search will hold you down and leave that fear that an hour or so may pass but they might/can contact you again.

It led to being held down for 12 hour stretches in AOD and I actually kind of miss that...

[Von Manteuffel]

Captain Frederic John Walker RN, developed the "Creeping Attack", utilizing at least two escort vessels. One was a "directing" ship to maintain regular active sonar contact at a steady range and bearing with the U-Boat, while a second ship headed at a speed of not more then five knots towards the sub's last known position. This second escort had its detection gear turned off. Once in position, it would release his depth charges on the command of the directing ship hoping that its approach had not been detected by the submarine.



I've met something like this kind of tactic in SH III, with two escorts taking it in turns to "direct" / ping while the other makes its attack run. Still not sure about the tactics of Japanese DEs and DDS in SH IV.



Thank goodness I've never met "Operation Plaster," also developed by the redoubtable Captain Walker. Basically , at least three escort vessels move in line abreast literally plastering an area with a large number of depth charges set up to 550 feet at five second intervals. A fourth or even fifth ship would take station a distance away from the activity while maintaining sonar contact with the target. The steady stream of DCs would virtually overwhelm the U-Boat and, if the original range and bearing fix was good, its destruction was often certain.:huh:

[Peto]

And that is my point exactly. In AOD they would use the creeping attack as it was intended ie--you couldn't hear the one coming that was actually making the attack (he was going too slow and not using active sonar). And it was brutally effective.

None of this is to bash SH3 or 4. I like them both very much and still get my share of virtual "thrills" from them. I just wonder why some of these escort techniques which were used weren't programmed into the sim. A ladder search or a line-abreast search for a lost submarine contact should be fairly easy to replicate with today's computers (they managed it on my PS1 386SX).

Again-this isn't a complaint but just more of an observation. As if things aren't tough enough sometimes, I go looking for tougher escorts LOL.

It's just the masochist in me ;)

Peto

[Von Manteuffel]

I think certain aspects of escort tactics are coded into both SH III & SH IV. I've certainly lost contact with a hunting escort which has slowed right down, or even stopped.

One thing I personally find unsatisfactory in both games - especially considering the availability of Time Compression, is the comparatively very short time for which surface vessels hunt, or wait - "Johnnie" Walker called it "hovering" - after they actually lose contact with a sub. It would often be for several hours. The escort commanders knew the submerged duration of a U-Boat and were prepared to wait in the area until lack of air forced a submarine to surface. It was an acceptable tactic. Sometimes the commander of a convoy's, or task-force's escorts would order a vessel to "hover" in the area a sub was last contacted. At least it kept the sub pinned to very slow progress, often allowing the convoy etc to get away.

Waits of 12 hours were quite commpnplace and some hunts lasted for up to 24 hours.

While I'm on the subject of what I find to be "not quite right": I don't think either SH3, or SH4 give enough weight to HD/DF - locating the area in which a sub was operating through its radio transmissions. It was, after code-breaking, probably the most effective means of locating ( albeit roughly ) submarines at sea.

[Frederf]

It is my understanding that the "bending sound sonar floor" is more prevelent at flat angles than looking straight at the bottom. Should work the exact same way as mirages in the desert, where light is bent around the abrupt density layer near the hot hot sand.