Depth Charge Lethality Poll
 

Hard data about this is very hard to com by. All the various navies seemed to think that a 300lb DC would be lethal within an average of about 6 meters. They don't list the depth, however.

That means a single DC within that range will kill a sub, or force it to the surface.

Current DCs are no where near that effective. Not even close at 6m. You can have them go off in contact, or actually inside the sub and it won't kill the boat for sure. I did a lot of testing on this, and single DC kills are virtually impossible.

So, the questions...

First, in the case of depth charges detonating close enough that the explosion graphic overlaps the hull (2-3m), should a single DC on an undamage sub be:

1. Certainly fatal.
2. Almost Certainly fatal (75%+).
3. Probably fatal (51%+).
4. Possibly fatal (10-50%).
5. Rarely fatal (<10%).
6. Never fatal.

Second, in the case of the 6m radius mentioned, should a single DC on an undamaged sub be:

A. Certainly fatal.
B. Almost Certainly fatal.
C. Probably fatal.
D. Possibly fatal.
E. Rarely fatal.
F. Never fatal.

FATAL means the either an instant spinning death screen, damage that REQUIRES blowing tanks to surface, or a mission kill (no more engines, props, fuel, etc).


My personal answers would be: 2 and D, given no good source to prove it otherwise. I tend to think it might more realistically be 1 and C, however. The current game (stock) is 4 and F, as a comparison (with any mod that doesn't up DC EF values or radii—so stock, rfb, and TM are here).

tater

I'd say 3 and D but 2 and D would be better then stock.


I wouldn't want the game to be too hard if you know what I mean.

Well, when I finally dial stuff in, I might make a couple versions available. An overall mod to the dat/sim/eqp files for the ships that all use, and a couple versions of the zon with different EF values etc. Just curious what people think so I know how to dial 'em in.

I should add the caveat that single DCs WILL kill you right now if they are in virtual contact (inside MinRadius) and the boat is DEEP. Then it will domino since the boat will instantly be below crush depth. For this I am assuming only moderate depth, perhaps 40-50m (IJN claimed a single 250kg GP bomb turned DC would kill a sub---about equal to their 162kg warhead type 2, maybe less cause bombs have more jacket, less explosive than DCs).

Personally, what I really miss a lot of times is a chance to die slowly. I've no objection to direct or near-direct hits being very deadly, but I'd prefer it'd end with my boat flooding uncontrollably while I try to blow ballast and lose the battle than just having the control taken away instantly and the boat plunging down. :hmm:

At distance, I'd like minor compartmental damage to be a bit more frequent.

I agree with this. In older sub games (i'm thinking it might have been SH2) I remember receiving major flooding in my bow compartments which caused my sub to slowly sink. Luckily I was in shallow enough water to hit the bottom and be able to slowly repair. I haven't had this happen in SH4 although that could just be the luck of the draw.

Either way, i'll never forget that moment. I thought I was done for but someone was looking out for me.

This poll is for "shacks." Direct hits inside what was considered lethal (6m) and in virtual contact (well within the game's MinRadius value).

The distant damage is then semi-easy to tweak with MaxRadius.

Right now there is no such thing as a single hit kill on a sub. Just doesn't happen at moderate depth (it will if you are near crush depth).

Large MaxRadius values make a single hit do damage to more compartments, which increases "contact" lethality, but not enough. If the EFs are upped a lot, and the radius is still huge, they become too deadly presumably.

Oddly, I made some DCs with the MinEF at 499 and the MaxEF at 500, and still didn't get 1 hit kills.

tater

1st post edited:

FATAL means the either an instant spinning death screen, damage that REQUIRES blowing tanks to surface, or a mission kill (no more engines, props, fuel, etc).

Again, this is only for "skin kills" where the bomb detonates in virtual contact for part 1, and the presumed lethal radius for part 2.


tater

I also have to agree with CCIP. The instant death screen sucks bad. I modded the U-boat armor levels in SH3 for my latest mod to where the U-boat will not be instantly destroyed followed by a death screen. Now, the U-boat will only be destroyed by hull integrity reaching zero from being dragged down by flooding and being crushed or being blown to pieces on the surface. An instant death screen from one close depth charge may be the most realistic, but it sure as hell isn't fun for a game.

But I agree with Tater. One or two very close depth charges should be enough to kill a sub. Just not instantly.

RE : instant death

I think the cause in this might be.. i suspect, some of the fundamental mechanics have changed in code.

For instance "crash speed". It used to function as a variable about how fast, or slow your sub bleed hitpoints when below crush depth. Set it for real low number, you sub crushed real slow, and you had time to recover.

It does not do this in Sh4. The game seems to making an arbitrary decision that once you've been blow crush depth for X amount of time - game over, period. Going below crush depth, i did not see any H.I loss at all. just 0% damage and then BAM 100%, with nothing in between.

Maybe the speed is still too high and i need to slow it down more? but i doubt that will solve anything except to delay the abitrary decision the game makes.

2,D

I think it's important to add that the ability for a single DC to kill a sub becomes a little more important when the escorts have realistic numbers of charges. If you only need to avoid 18 early war, instead of 80, they need to have a more realistic effect. Of course we then get into the problem of not being able to out dive the DCs, or the limited settings available for the DCs (30/60/90m).

So I would tend to err on slightly less lethal.

Watching a zillion DC attacks with external cam on, I was stunned at how many DCs it took to kill me where they were touching or even inside the sub. Any of the possibly fatal settings would mean at the very least pretty severe damage, which is also fine I guess.

tater

Doesn't the effect of a DC depend on the actual depths as well? Wasn't it: The deeper the sub the lesser the damage range of a DC?

I don't think the game takes depth into account at all. In fact, since DCs can do hitpoint damage, which makes your crush depth more shallow, the deeper you are when hit, the more dangerous it is for you.

Cool pic I found:

http://www.fas.org/man/dod-101/navy/...s/IMG00003.GIF

A quote from a ww2 USN manual:
May prove fatal at ~6m for what would be the biggest IJN DC (162kg warhead). That maps to D I guess. 2 or 3 and D...

tater

Let me know if I can help you with any testing.

Ok, first you are right about depth being a factor. But pondering on this I started to wonder if it doesn't have as big an effect effect on cumulative damage you take as how easy it is to exceed a catastrphic stress. I.e. less than catastrophic and the hull rebounds, but because of the increased depth and stress on the hull, the added pressure and uneven application of pressure makes it easier to exceed a catastrophic point. So if it's not catastrophic, you don't take significantly more damage, only a smaller percentage more, but you exceed the catqstrophic failure point easier. Wish I could find a good paper on this.

The reason doublig the charge doesn't double the range is because of the way the shock wave dissipates.

Here's an example I was able to dig up talking about a shock wave in air:
http://www.makeitlouder.com/document...stimation.html

In water, there is more force dissipated faster because of the density of the fluid.

So for grins lets say a 300 lb and 600 lb DC have 100% effectiveness at 1m and we'll use a loss factor of 0.5 for every 2 meters past that. (These are merely for illustration, not actual numbers and rounded of to the nearest 0.X)

So here is the theoretical dropoff of 0.5 for our example:
distance . . . 300lb . . . 600lb
3m . . . . . . . 150 . . . . .300
5m . . . . . . . 75 . . . . . 150
7m . . . . . . . 37.5 . . . . . 75
9m . . . . . . . 18.8 . . . . . .37.5
11 . . . . . . . 9.4 . . . . . . 18.8
13 . . . . . . . 4.7 . . . . . . .9.4
15 . . . . . . . .2.4 . . . . . . .4.7
17 . . . . . . . 1.2 . . . . . . .2.4
19 . . . . . . . 0.6 . . . . . . .1.2
21 . . . . . . . 0.3 . . . . . . .0.6

So even though you start of with a charge twice as powerful it only takes a distance 10% greater, not twice as great for the force to drop below 1 lb

This is an extremely simplified example because I'm leaving out possible log or natural log functions which would make the drop off faster past a certian point, and I'll guarantee the factors are off. But this shows why doubling a charge does not make the DC capable of creating the same damage at twice the distance of a DC half it's size.

Tater, just FYI, your depth charge settings could concievably change if you use some of the changes ive done to the submarines zon files ive been yapping about since last night.

I'm sure they will, lol.

I assume that in game the damage falls of linearly with distance between MinRadius and MaxRadius.

You dropped the armor, but not the ALF, right? So 20*4=80. 80 is now the damage cutoff.

So if a charge can do 230 points at 4.5, it will do 115 at 9.5m, it'll do 80 at 11m. Outside 11m it does nothing at all.

tater

I love what you're doing to try to make the D/C experience more realistic, BUT, I hate to say it but this is a pretty meaningless poll/question the way it is posed in a relative vacuum.

If (and this is an assumption I acknowledge is true for me but not necessarily true for everybody) the "best" realism is one which achieves a realistic end result - in this case a realistic chance of escaping with damage vs being destroyed - then you can't really answer this question about what an essentially direct hit would do to your sub unless you can also answer/address the question of whether the percentage chance of these direct hits is reasonably accurate/realistic in the game. Obviously, if it is, then you would want the results of those direct hits to also be reasonably accurate/realistic. BUT, if for some reason the AI escorts typically get a much higher percentage of such direct hits than would be historically accurate, then for sure you would not want to make the effects of such direct hits be too lethal (even if they would be IRL) because then you would have distorted the lethality outcome too much to the deadly side.

From the comment below ("Watching a zillion DC attacks with external cam on, I was stunned at how many DCs it took to kill me where they were touching or even inside the sub.", it's hard to tell for sure what was happening on a percentage basis, but it sounds like maybe there were a large number of direct hits. If there weren't all that many US subs lost due to D/C attacks, and the game is throwing off a lot of direct hits, then it doesn't sound like a good idea to make direct hits too lethal unless you can also reduce the number of direct hits experienced.

The best result would seem to be some way to increase the number of minor (but significant) damage results, such that D/Cs would be something to fear and could cumulate to deadly damage, but where the player would still have a reasonable chance to at least try to deal with the damage most of the time. After all, if you're not playing with external views on while you're being attacked, then you really don't know or care how close the D/Cs really are (i.e., whether they're 20 feet or 30 feet away) - all you really know is are they close enough to be damaging you or not.

Of course, that assumes that the damage control model in SH4 works or can be made to work like it eventually did in SH3 with LRT. So far, I haven't encountered the right circumstances to test the damage control system meaningfully, so I don't kow whether it works or not, but I hope so - otherwise, you might as well go for the instant screen of death with super lethal D/Cs and spare us the disappointment of dealing with a damage control feature that doesn't work.

Excellent points.

One thing, my changes to the DCs also includes accurate loads of DCs on the escorts. So some might carry 18 DCs instead of what they now carry (80).

Also, I should be clear. I was trying to get shacked. My test case was a single DC exploding so that the explosion graphic touched my sub. I made an Elite Minekaze with 1 roll rack and used TM sensors, and loaded up the Minekaze like bungo pete with sensors on top of that. If a DC exploded nearby, but didn't touch I quit the mission and started over.

Even then, had I been trying to evade, and/or deeper than 100 feet, he'd not have hit me often in all those tests.

Really, the point of the poll is to find out how many folks think that it should be possible for a single DC to take out a sub. I agree that if they are shacking you all the time, then they need to be toned down to have historical outcomes. I would assume, however, that the sub goes deep and tries HARD not to get hit as a baseline as well (I'm sure skippers treated a DCing as the life or death situation it was).

I might also be inclined to make single DC kills unlikely for the type 95s since in RL they only had 2 or 3 depth settings, and the deepest was 60m for most of their lifetime in service.

tater

Understood - I certainly think it should be possible for one DC to kill the sub, though hopefully not that likely, and it'd be nice if it weren't the immediate sceen of death, but where you'd have at least a minute or two maybe to try to blow tanks and make it to the surface, or maybe hit bottom if you're shallow enough and send the survivors out through the escape hatches with the breathing gear :lol: