[WAITING FOR SAVEGAME] Depth Charges and Passive Sonar

[pgatcomb]

I've been playing some very early cold war scenarios using more or less slightly upgraded World War II equipment and I'm finding that it is exceedingly difficult to damage detected submarines with depth charges. I know that in the real world the odds of a clean hit were relatively low, but I decided to do a few experiments to see what happened. I would use 9 ace American DDs and attempt to hit a Generic Type VII moving at 5 knots. What occurs is a massive dog pile of destroyers spewing hedgehogs and air launched depth charges. The problem becomes that the destroyers can't get close enough for a clean attack or "pass over" so the ones that do manage to deploy their charges find their stuff landing 100s of meters behind the intended target making them pretty much helpless against that sub.

The cool part was when I manually set the sub to 0 knots, the rain of depth charges really began and the sub was sunk. This is all with a periscope depth sub. Lots of work from 9 destroyers... So I'm not sure what to think at this point. Probably things weren't intended to be used the way I'm using them anyway.

Second part is a bit of a question. I have some background on active/passive sonar and I am curious how the quality of a passive sonar set is modeled. On the wiki it appears that all passive sonar sets have properties for range, frequency range, resolution and generation. I assume sensitivity or minimum SNR of the set is a function of generation? It just surprises me sometimes the things that can and cannot be heard when knowing how loud they are (from the wiki in dB) at some ranges, even when taking into account convective layer and sea state.

Thanks!

[Luidzi]

May you post a save for the devs to look into?

As for the second question, I believe the dB values are an approximation and while they might differ a bit from real noise values, for simulation they are precise enough. If you have a specific case of detection that happens too soon or late, more details would be useful.

[pgatcomb]

I will have to put together a save, but if you wanted to test it yourself just make a type VIIc generic in the CWDB at periscope depth moving at 5 knots in a constant direction. Then have 9 Fletcher destroyers (as built, 1942 or 1943?) attempt to sink it with depth charges and hedge hogs in normal weather.

As for the dB values, I have no doubt they're pretty accurate based on a quick glance, my bigger question was how the game determines what range it can detect a given sound as there is no information on minimum signal/noise ratio for detection using a passive set. I imagine the developers use super accurate charts for underwater noise based on sea state as well as the attenuation of different frequencies by distance, so it's just a matter of finding out what the minimum received signal is considered detectable. Technically radar would operate the same basic way.

[ComDev]

Thanks for your report pgatcomb. Like Luidzi said, we need a savegame [8D]

[pgatcomb]

Alright I've played with it quite a bit more and gotten even more insight:

Seems the issue isn't so much the charges as it is detection of the subs. What's happening is that the destroyers are getting right on top of the submarine, they lose it's exact spot and fail to deploy their weapons correctly as they have an ambiguous target. I used a super modern submarine to track the type VIIC as the destroyers went about attempting to sink it and they were very successful at it.

I don't see where to attach things on here, probably since I don't have enough posts or whatever. I guess my next question is "what world war II era destroyers had passive sets?". I went through a few selections on the baloogan wiki and the database and didn't find any sonar systems other than active sonar sets. Am I just missing a whole class of destroyer from that era that had active and passive?

[Rory Noonan]

ORIGINAL: pgatcomb

Alright I've played with it quite a bit more and gotten even more insight:

Seems the issue isn't so much the charges as it is detection of the subs. What's happening is that the destroyers are getting right on top of the submarine, they lose it's exact spot and fail to deploy their weapons correctly as they have an ambiguous target. I used a super modern submarine to track the type VIIC as the destroyers went about attempting to sink it and they were very successful at it.

I don't see where to attach things on here, probably since I don't have enough posts or whatever. I guess my next question is "what world war II era destroyers had passive sets?". I went through a few selections on the baloogan wiki and the database and didn't find any sonar systems other than active sonar sets. Am I just missing a whole class of destroyer from that era that had active and passive?

If you're doing quick replies (by typing in the box at the bottom of the screen) you won't see the option to attach. To attach a file, click the orange 'post reply' button and then the 'click here to upload' link. Supported file types are .jpg, .zip... and I think that's it. To upload a save you'll need to zip it up.

[pgatcomb]

File attached.