GWX KC Edition - Depth Charges

[Mowgli]

I have just spent several hours evading a J Class destroyer in calm weather. It was almost impossible to shake it but I got away in the end with some damage.
Because of the length of the attack I had a chance to make several notes.
It seemed the DD had endless depth charges, I counted at least 40 explosions and so afterwards looked up how many they carried - 45 according to wikipedia. So how does the game allocated DC to destroyers or are they unlimited?

Next I noticed in the numerous attacks that the time from the warning of depth charge in the water varied. At the end at 110 metres it took 38 seconds after being dropped before the explosion.
With this information could I calculate the depth settings of the DC and so adjust my depth in between.

I used SOP to evade.

[Hooston]

The charges are limited, I believe to 50 per escort. This is in the config files somewhere but I can't find it. When it has run out the destroyer will keep attacking but not drop anything. Each escort will go away when it has had no contact for about 20 minutes, so run silent run deep as soon as they start attacking the wrong place.
The real life number of charges varied tremendously, from about 20 on a 1939 fleet destroyer to 100 or more on a late war ASW ship. Individual captains would often squeeze a few more charges onboard and take a risk with stability. So 50 is not a bad choice. Towards the end of the war some escorts were able to reload from merchantmen in the convoy in calm weather.
IRL guessing the depth of the target was educated guesswork, based on the distance at which the submarine disappeared below the ASDIC beam, until late in the war. The charges would thus be dropped with a large spread of depths. The charges were not very accurate in terms of depth in any case, with settings typically at 50 feet intervals. in game the charges are very accurate in depth terms and you can dodge with a 20m depth change as the escort runs in. Particularly useful if caught in shallow water, but very unrealistic.


...oh and you can go A LOT deeper than 110m!!!!

[Mowgli]

Originally Posted by Hooston

...oh and you can go A LOT deeper than 110m!!!!

Thanks for the reply, well I counted about 42 but I was really interested in the timing of the explosions after they had been dropped because, if for example in my case it took 38 seconds to explode at 110 metres (I know I could have gone deeper but I start at 80 and gradually go down) then I have options to either raise or lower the depth.

[Kpt. Lehmann]

Hi guys.... Mowgli & Hooston.

It has been a very long time since I set the DC parameters.
Believe it or not, I actually loosened up the "laser accuracy" of the DC's in GWX 3.0 ----> GWX-KC. The sink rates of the common depth charge are also very very close to real life values. I may have increased the sink rate and blast radius a smidge.... but that was only because ASW vessels when moving slow and dropping DC's would sometimes blow their own sterns off.
That in turn made for unrealistically vulnerable targets.

I'd rather not speak on exact parameter settings though, because I don't want to ruin your immersion.

In any case, I think that the memory of the old stock SH3 SUPER-deadly DC's has been more or less lost over time.

I am really glad you are enjoying yourselves though.

[Mowgli]

Originally Posted by Kpt. Lehmann

Hi guys.... Mowgli & Hooston.



I am really glad you are enjoying yourselves though.

Most certainly am and it is super stable, you did a great job. Thank you.
Any plans to add to it, although I cannot think of anything of the top off my head.

[Tabris]

Thanks for bringing this up. A few weeks ago I lost a duel to a lone DD off the West African coast. I counted the bombs, as one does when fighting a single escort. We were sunk after 110 bombs. 110. I did not note the exact type of vessel, but it was one of those interwar DDs. So A&B or C&D, possibly V&W.

I looked at the relevant Library files in S3D immediately after. I am not a pro modder, so I make no strong assertions here, but it seems each DC launcher "weapon" (that which occupies a node in the ship's .eqp file) contains 40 bombs. If I'm correct, that means that DD attacking me still had 130 bombs left, as he had four K-guns and two DC racks, totaling 240 bombs. Totally ludicrous, if true. This would mean the later dedicated convoy escorts like JC Butler and Evarts, which have 8x K-guns and 2x racks, would have 400 bombs! It also means that dedicated fleet DDs like Tribal, which have only modest ASW weapons (two K-guns, one DC rack) are carrying four of five times as many bombs as they could historically.

After much thought and calculation, I changed the number of bombs per weapons station down from 40 to 12. It's my hope that this doesn't nerf the AI too much, but it should make outlasting the enemy's ammunition at least possible. This way, Modified Black Swan would have 120 bombs, which is still 10 more than they carried in real life. I have yet to playtest the change but I'll do so soon and report back.

- Tabris

[Hooston]

I've had this debate here before. I believe the charges limit is by weapon type, not directly by ship type. However I was convinced by others that the charges were somehow per escort rather than per launcher. I have had escorts run out of charges and I don't think it was as many as 40 per launcher, but I'm not sure. Do you think maybe it is 40 per launcher type - so 40 for all the K launchers plus 40 for all the rails?Also I'm unsure if the number of charges remaining is preserved when you save the game.
It's tricky. The game escorts get all worked up and attack again and again even if they have no ASDIC contact. The ocean is a big place and dropping charges where a target used to be is not really going to cut it. In real life they would restart a methodical search once they lost contact and would not waste charges on a guess unless they wanted to scare a boat into staying deep - for example when giving up the hunt or in really bad ASDIC conditions like those near Murmansk. Real ASW hunts would last for hours, even a whole day for a late war support group. This is not great game play for most people.
There's not much the modders can do about the AI, so they have to do the best they can.

[VikingGrandad]

Originally Posted by Hooston

I've had this debate here before. I believe the charges limit is by weapon type, not directly by ship type. However I was convinced by others that the charges were somehow per escort rather than per launcher. .

Not an area of expertise for me, but from what I can tell, both aspects are correct: each launcher/rack type has a limit (in GWX KC, it seems to be set at 40 DCs for each launcher, and lower amounts for racks) - and thus each ship type has a DC limit according to how many launchers and racks it has been equipped with, e.g. if a specific DE is configured to be equipped with 4 x launchers (and those specific launchers are set at 40 DCs each) and 2 x racks (and those specific rack types are set at 10 DCs each), that DE will have 180 DCs in total.

Historically, I think the multi-purpose DDs generally carried around 30-40 DCs in total, and the specialised ASW DEs were designed to carry many more, around 100-300 per ship, depending on the class and period of the war.

[Shadowblade]

it looks like aggressive sinking of DDs is still good tactic

[Tabris]

So, I preformed some tests. It does seem the "depth charges ALL" library file, and the "ammunition" value for each weapon therein, is what dictates how many bombs a ship carries. I lowered the value for every single weapon to 3, deliberately attracted an escort's attention (if my wife is reading don't take that out of context) and watched has he dropped precisely three bombs from each rack and fired three from each K-gun before running out.

Of note is that escorts do not alter their behavior when out of bombs: They will keep making attack runs on ASDIC contacts, just without dropping anything. To anyone familiar with SH3, this won't be surprising - the enemy will never "give up" and sail away from a contact which they can still detect. In light of the AI's behavior, one could make a convincing argument that restricting their ammo is academic, but since I'd still like the *option* to outlast their attacks in the rare case of it being necessary, I will continue tweaking the balance.

Now, I'm far from confident that I understand this system perfectly. For one or two of the escorts, I think Evarts is one of them, they only have two nodes in the .eqp file for K-guns, but I know for sure they have eight K-guns in the game. I'm not totally sure how the game handles ammunition if the node is duplicated and used more than once.

As others have pointed out, the AI always goes whole-hog whenever it launches an attack. Each K-gun fires once, and the racks will drop four bombs per run, maybe sometimes more, every single time, even if the enemy is just "guessing." 12 is definitely too few bombs in light of this behavior for the racks, BUT, we may be able to take advantage of this behavior to represent the enemy beginning to conserve his ammunition: If the racks run out first, after, say, 6-10 attacks, but the enemy still has ammunition left for the K-guns, he'll keep using those but each attack will include fewer bombs. For all I know, this is precisely the intended behavior behind giving them 40 bombs per slot: 40 means 10-12 attack runs with the racks, but 40 attack runs with the projectors (or I guess 20 attacks in the case of the Y-gun). The problem is, 10 attack runs means 80 bombs with the racks alone! So there has to be a comfortable middle ground somewhere here.

[Kpt. Lehmann]

@Tabris, just to say so 'out loud,' even when an ASW vessel is out of depth charges and continues running about overhead.... keeping you submerged means that he is still doing his job. The convoy still gets away.

Also, to Hooston, Mowgli and other interested parties. When I stated that as part of the solution to stock SH3 ASW vessels blowing their own sterns off with depth charges, and loosening the old SH3 stock laser guided DC's, I mentioned part of what I did was to increase the DC blast radius. That was inadvertent. What I did was to reduce the DC blast radius. Those changes (that I made back during the development of GWX 2.0 in 2007 or 2008 IIRC) largely put a stop to ASW vessels trying to sink themselves.

However, the smaller blast radius is intense. Depth charging sessions are longer in average duration than stock SH3, but delivered damage when sustained, I think is about the same. There's more to depth charge bombardments in GWX, but I don't want to give away too many spoilers and ruin immersion for players.