Active & Passive Sonar in SHV

[Méo]

I've heard or read somewhere (i don't remember exactly) that escorts had to wait 10-15 minutes after a depth charge attack before using ASDIC again. Do you guys can confirm? (i've searched but found nothing)

[Méo]

In the meantime i found that u-boat could hear a convoy (if speed ≤ 4 knots) up to 50 nautical miles. Seems like a lot to me.

http://www.uboat.net/articles/id/52

[Jaeger]

hi meo,

i have read these two points here in the forum many times, seems to be correct information. two points which would affect submarine tactics a lot. i have mentioned this point long time before: they have to implement another sound volume from convoys in opposite to single merchants...

also, the pause, destroyers have to wait between two dc attacks combined with realistic acceleration and turning values would give a new feeling of antisubmarine warfare.

[Sailor Steve]

Originally Posted by Méo

I've heard or read somewhere (i don't remember exactly) that escorts had to wait 10-15 minutes after a depth charge attack before using ASDIC again. Do you guys can confirm? (i've searched but found nothing)

I think it was more like 1-2 minutes, which is still a lot compared with the zero time in-game; which was more due to turnaround time than actual water disturbance. I say this because it's my understanding that once the hunter-killer groups started working, one DD would follow the u-boat and guide the others in, with no loss of contact at all when they dropped their charges.

[Méo]

Originally Posted by Sailor Steve

I think it was more like 1-2 minutes, which is still a lot compared with the zero time in-game; which was more due to turnaround time than actual water disturbance. I say this because it's my understanding that once the hunter-killer groups started working, one DD would follow the u-boat and guide the others in, with no loss of contact at all when they dropped their charges.

Cool, thanks!

It would be a must to correct this in SHV.

i think it was basicly just the time it took for all the bubbles to surface so they wouldnt interfere with the sensors anymore

[Méo]

Originally Posted by WEBSTER

i think it was basicly just the time it took for all the bubbles to surface so they wouldnt interfere with the sensors anymore

Make sense, to me it would have to be simulated.

I'm asking this because in GWX 3.0 it was nearly impossible to survive depth charge attacks in late war, even with a type XXI.

Destroyers were just doint it too perfectly.

[Méo]

Originally Posted by Jaeger

hi meo,

i have read these two points here in the forum many times, seems to be correct information.

Hi Jeager,

I searched for thread about Sonar or ASDIC and found none. (at least in the SHV forum)

Do you remember for how long water disturbance lasted in real life?

[difool2]

I haven't really been able to get a straight answer as to how far away WWII-era hydrophones could pick up surface ships. In Dangerous Waters, with a nice modern sonar suite and towed array, you can detect surface ships at 50+ kilometers, IIRC (and, if you get lucky with a convergence zone, you can get a brief contact at even farther ranges). WWII sub skippers certainly didn't think that staying submerged & relying on the sonar man, vs. the lookouts if surfaced, was a better choice for expanding their detection radius. In both games the former is almost always the best choice, esp. if you man the phones yourself. But there's so many confounding factors involved that anecdotal reports (from the real war) on this point are almost completely useless.

I would like to see them model CZs and bottom limited enviroments (certainly thermal layers have to be there too, even if the Germans had no viable way to detect them). Something doesn't cease to exist just because nobody was aware of it back then.

[Greenhornet]

Escort speed also had an effect on detection, both modern and WWII era. I also find that an escort in SH4 can still hear you in its baffles/prop wash, as the escort went by I would speed up as I entered the area astern of the ship where I thought I couldn't be detected only to find they could hear through the propellers!

In SH2 the we had Uber Destroyers, in SH3 with GWX I had DD's making dry runs for hours with no more depth charges, and in SH4 the japs were OK but the Allies couldn't find you at all....

[Ducimus]

I'll bet my bottom dollar how the AI functions in SH5 will probably be not all that different from SH3/4. The system they have in place works well enough (though it could use an improvement in limiting max depth on depth charges), so from a development standpoint, it's more logical to direct manhours to areas that do not work so well, or not at all.

Originally Posted by Greenhornet

in SH3 with GWX I had DD's making dry runs for hours with no more depth charges,

Sounds like they ran out of depth charges. How many cans a DD has is not infinate. Stock ammo count, is, i believe, 40 depth charges. So it seems unlimited, but it's really not.

and in SH4 the japs were OK but the Allies couldn't find you at all....

You have a couple respones to your tread on that subject. I linked to you the info on how to tweak it. I would work on allied ASW myself, but i just don't have the time or motivation. If i did though, im quite sure i could allied units sinking alot of player uboats.

[Jimbuna]

Originally Posted by Sailor Steve

I think it was more like 1-2 minutes, which is still a lot compared with the zero time in-game; which was more due to turnaround time than actual water disturbance. I say this because it's my understanding that once the hunter-killer groups started working, one DD would follow the u-boat and guide the others in, with no loss of contact at all when they dropped their charges.

Agreed...the 'listener' would focus directly on the contact point and would send an active 'confirmation' ping if the contact was lost.

The U-boat lost the vast majority of Hunter-Killer engagements in RL, at best often having to surface and be destroyed by surface ship gunfire or aircraft (if the group had an escort carrier.

Contact from a single DD will be lost during the run-in.
At what range contact is lost, is one of the determining factors at how deep the DCs are set.
The longer the range, the deeper you are.

As Jimbuna points out, Hunter Killer Group is a whole new ballgame.
When the Killer(s) drop their charges, and all hell breaks loose, the Hunter will temporarily loose contact but, your position, relative to him, hasn't changed much, so he knows where to train his active sonar. Hydrophones will be negatively effected for quite some time.
2 Hunters is best, as one will always have contact with your broadside.

Hydrophone Range was "kinda guessie" in real life.
Known and unknown conditions having effect.
The brits figured a uboat could hear the noise of a convoy at "80 or even 100 miles away".
HOWEVER, BDU thought the boats had a better chance of finding contacts, on the surface.

This seems to be one of those topics that:
The more we learn, and the more sources we check,
the more confused we become.

The main sub-killing weapon that convoy escorts lacked was TIME.
Hunter Killer Groups, and other unattached surface units had no shortage of this commodity.

Known Sub:
Destroyers + Time = Dead Sub.
Then and now.

[karamazovnew]

So...
1. Combined sound from convoys should travel longer... checked.
2. DDs should have realistic number of DC... checked.
3. Depth charges should hinder passive detection... checked.

But what about hiding inside a convoy and using wrecks as a sound screen? Ok I know that the sub has a specific noise that can be picked up even if it overlaps the sound of a merchant, but each knot of speed is important when dodging DDs and I doubt that any sound man could pick up a 2/3d's running sub on top of a flank running (and panicked) merchant.

[Jimbuna]

Originally Posted by karamazovnew

But what about hiding inside a convoy and using wrecks as a sound screen?

Good point.......asdic can hear/listen through land in SH3