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reumatiib
04-06-2005, 11:43 PM
Learn to keep quiet until you research...

This source is from the DESA (Destroyer Escort Sailors Association)

Note that 30 yards = about 29+ meters and 10 yards = about slightly less than 10 meters or 30 feet. 30 feet = KILL on German U-boats, 90 feet = damage on them. This is about what I once read long ago in a German source about U-boats.

"The depth charge, with its 300 to 600 pounds of TNT, was the traditional antisubmarine weapon. However, a depth charge barrage required a high degree of accuracy to score, particularly against the double-hulled German U-boats. The "water hammer" effect of a 300 pound depth charge required an explosion within 30 yards of the submarine hull for damage and 10 yards for a kill. The 600 pound depth charge lethal area was considerably enlarged. They had a "teardrop" shape with tail fins, like aerial bombs, to make them sink faster. Depth charges were detonated by hydrostatic pressure, and depth was set before firing. Later models also had magnetic impulse detonators which would fire when in proximity to a submarine. Japanese submarines, lacking the hull strength and depth tolerance of their German counterparts, were more vulnerable to destruction by this weapon. A DE carried about 100 depth charges."

http://www.desausa.org/destroyer_escort.htm

Note: the 600 lbs. depth charge was about the mid range in WWII and this would have a damage range GREATER than 30 yards and a kill range greater than 10 yards. So much for the Hollywood movie effects of Depth Charges going off right next to subs that then survive!

More coming.....

But the point is: SH3 depth Charges are too weak. The DEV TEAM SHOULD PAY HEED.

Until the fix is made I will have to continue to scrape my hull on the bottom as I leave port on purpose - so as to weaken my sub to give the DDs a fighting chance.

reumatiib
04-06-2005, 11:43 PM
Learn to keep quiet until you research...

This source is from the DESA (Destroyer Escort Sailors Association)

Note that 30 yards = about 29+ meters and 10 yards = about slightly less than 10 meters or 30 feet. 30 feet = KILL on German U-boats, 90 feet = damage on them. This is about what I once read long ago in a German source about U-boats.

"The depth charge, with its 300 to 600 pounds of TNT, was the traditional antisubmarine weapon. However, a depth charge barrage required a high degree of accuracy to score, particularly against the double-hulled German U-boats. The "water hammer" effect of a 300 pound depth charge required an explosion within 30 yards of the submarine hull for damage and 10 yards for a kill. The 600 pound depth charge lethal area was considerably enlarged. They had a "teardrop" shape with tail fins, like aerial bombs, to make them sink faster. Depth charges were detonated by hydrostatic pressure, and depth was set before firing. Later models also had magnetic impulse detonators which would fire when in proximity to a submarine. Japanese submarines, lacking the hull strength and depth tolerance of their German counterparts, were more vulnerable to destruction by this weapon. A DE carried about 100 depth charges."

http://www.desausa.org/destroyer_escort.htm

Note: the 600 lbs. depth charge was about the mid range in WWII and this would have a damage range GREATER than 30 yards and a kill range greater than 10 yards. So much for the Hollywood movie effects of Depth Charges going off right next to subs that then survive!

More coming.....

But the point is: SH3 depth Charges are too weak. The DEV TEAM SHOULD PAY HEED.

Until the fix is made I will have to continue to scrape my hull on the bottom as I leave port on purpose - so as to weaken my sub to give the DDs a fighting chance.

macker33
04-06-2005, 11:58 PM
30 yards isnt that much,if the wind is right you can spit that far.

reumatiib
04-07-2005, 12:11 AM
Let's see 30 yards is nearly half the entire length of a type VIIA U-boat (64 meters). 30 Yards is what the smaller charges did, not the average. And 30 yards is covers well the zone where SH3 depth charges fail to effect my hull integ-stats.

But some people with eyes, can't see - and others may be hard headed Devs posting on this board.

Pr0metheus 1962
04-07-2005, 01:11 AM
Oh please! Do we really need two threads on the exact same subject. Face it, the developers aren't going to change this because it simply isn't broken. Your data is flawed, it comes from suspect sources. In short, it's not reliable, yet you choose to worship it as if it's a golden calf.

Depth charges simply weren't effective, especially in the first part of the war. Since that's the only period you've played in the game so far, you're hardly qualified to make a comprehensive or objective assessment.

If you really want to weaken your sub, the data is readily accessible in the zones.cfg file. Just lower all the armor levels. No need for the developers to get involved in your campaign to nerf the U-Boats.

Frederf220
04-07-2005, 01:51 AM
Fanboys like Beeryus aside,

Good to see some emperical data. I don't know why 300lbs of TNT is not effective in 1939 but is effective in 1943 supposedly. Did they update the laws of physics in the interum?

Damage at half ship length away... right, it's not at that point now.

HEAT.GRLSOV
04-07-2005, 02:12 AM
http://www.navweaps.com/Weapons/WAMBR_ASW.htm

http://www.navweaps.com/Weapons/WAMUS_ASW.htm

Nukem_Hicks
04-07-2005, 02:50 AM
After a recent MP game I have decided that, the debate over depth charges aside, the U-boat damage model might be a tad bit off. That, or the destroyer's 5 inch shells are far too weak.

The game, set on hard realism, involved a 6-boat wolfpack in XXIs attacking a convoy in early 1945. At one point my submarine broached during an attempted crash dive and I found myself on the surface in the middle of the convoy. At this point in the war every ship was heavily armed, let alone the 8 destroyers escorting the convoy. Watch from external view while my crew attempted to dive again, I counted no fewer than 38 direct shell hits on my sub before she exploded. Now, I know the XXIs were advanced, but I didn't realize they had armor plating. I've never heard of a 1000 ton iron canister taking 38 shell hits before succumbing.

I'm still not convinced that the depth charges need to be strengthed, but my sub resisted those shells far too easily.

Pr0metheus 1962
04-07-2005, 09:28 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Nukem_Hicks:
After a recent MP game I have decided that, the debate over depth charges aside, the U-boat damage model might be a tad bit off. That, or the destroyer's 5 inch shells are far too weak.... <HR></BLOCKQUOTE>

Yes, shellfire damage is way undermodelled.

SS.DJSatane
04-07-2005, 09:51 AM
Btw, do ships actually run out of Depth Charges? There are some armed trawlers with only single depth charge line on back and they are small, yet I never seen them run out of depth charges yet... Anyone actually seen a warship run out of depth charges or ammo?

Further, before devs even touch damage with depth charges(if there is need) they should fix the fact that in multiplayer noone but the host player can hear pinging, or get any warnings from crew such as "depth charges in water" or "we are being pinged" which makes it extremely difficult when you try to play multiplayer session on realistic settings.

Pr0metheus 1962
04-07-2005, 10:20 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Frederf220:
Fanboys like Beeryus aside... <HR></BLOCKQUOTE>

Clearly you haven't been around very long if you think I'm a fanboy.

reumatiib
04-07-2005, 04:53 PM
reminds me of those who say: "my country - right or wrong..." You have to ask such people first: "Just what evil acts would it take for your government to do to force you to turn against it?" Make them come up with an answer, and if they don't, then say: "I see, if your country slaughtered and roasted children for a feast you'd still stand behind it?"

In a like way one would have to ask here: "just what data would it take to cause you to decide that the SH3 Team could have made a mistake about depth charges?" If such people can't answer that, then it would become plain that NO DATA (even from experts in the field) would cause them to open their shut-little minds.

Some people are just that way - but in this case I think it goes back to the fact that they don't want to realize that they are not the U-boat aces they imagined they were. And no one like's to have their balls shrink in size....

Nukem_Hicks
04-07-2005, 05:55 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by reumatiib:
reminds me of those who say: "my country - right or wrong..." You have to ask such people first: "Just what evil acts would it take for your government to do to force you to turn against it?" Make them come up with an answer, and if they don't, then say: "I see, if your country slaughtered and roasted children for a feast you'd still stand behind it?"

In a like way one would have to ask here: "just what data would it take to cause you to decide that the SH3 Team could have made a mistake about depth charges?" If such people can't answer that, then it would become plain that NO DATA (even from experts in the field) would cause them to open their shut-little minds.

Some people are just that way - but in this case I think it goes back to the fact that they don't want to realize that they are not the U-boat aces they imagined they were. And no one like's to have their balls shrink in size.... <HR></BLOCKQUOTE>

You couldn't be more incorrect if you're saying that about Beeryus. I can't help but notice that you're quite new here. Beeryus has earned a well-deserved reputation for nitpicking EVERYTHING about this game. The man strives for utter realism; he complained vehemently when he learned that every single last aspect of the game wouldn't be modelled entirely in German, a language he doesn't even speak. I'm sure you can accuse Beeryus, as you can anyone else, of a number of flaws, but selling himself short in terms of full realism is not one of them.

Pr0metheus 1962
04-07-2005, 10:09 PM
Thanks Nukem_Hicks. Actually my obsession with realism may be even worse than you describe: I didn't complain vehemently because I 'learned' that the US release of the game wouldn't be modelled entirely in German. I complained vehemently merely because I suspected it, LOL. On the other hand, I actually DO speak German, so I'm not altogether wacky in my realism crusade.

Reumatiib seems to delight in calling us pussies and telling us that we ought to desire a more deadly game experience and thereby somehow become "real U-Boat commanders". There's a weird idea if I ever heard one. I mean I'm not sure how playing a computer game can turn anyone into anything but a computer geek. If I went up to a real U-Boat commander and said I was his equal because I had sunk 200,000 tons in SH2, I'm sure the guy would either laugh his head off or punch me in the nose. The whole idea that this hobby can do anything for one's stature in the real world is ludicrous. It's just a game. If I want to become a 'real sub commander' the only way I can do that is to join the navy. Computer games, no matter how deadly the simulation is, can't help with that, so Reumatiib is barking up the wrong tree with that idea.

alanschu
04-07-2005, 10:58 PM
I think reumatiib only plays in the early part of the war (which is also when those 600 lb depth charges he talks about didn't even exist). Seriously, go play the 1943 campaign.

The same thread he discusses talks about how the depth charges were less effective on the German uboats than on Japanese ones.


Here's something from wikipedia:

http://en.wikipedia.org/wiki/Depth_charge

"Although the explosions of the standard 600-pound depth charge used in World War II were nerve-wracking to the target, an undamaged U-boat's pressure hull would not rupture unless the charge detonated closer than about five meters. Placing the weapon within this range was entirely a matter of chance and quite unlikely as the target maneuvered evasively during the attack. Most U-boats sunk by depth charges were destroyed by damage accumulated from a long barrage rather than by a single carefully-aimed attack. Many survived hundreds of depth charge detonations over a period of many hours; 678 depth charges were dropped onto U-427 in April, 1945. The U-boat survived."

FIVE METRES!!!!!

And that's from the late war 600 lb ones, not the 300 lb ones.


So who's "right" then. I suspect the "10 metre" kill range that you listed was probably "10 meters if you want any hope whatsoever of killing the thing, otherwise we're dropping 678 of them on you...only to not kill you."

mlody111
04-08-2005, 12:32 AM
I will say that Beeryus has been around for a very long time, but I have not even read a single post by reumatiib. That doesnt mean he is incorrect. Another thing I will say is that me and Beeryus had a very long discussion about the survivability in a sub-sim, which was still not concluded. http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

Go back to the topic at hand... Lets look at the facts. Mind you this is in the early years of the war.

1. VIIC uboat length = 67 meters
british mark VII depth change range = 12 meters
(at 6m it claims it will breach the pressure hull, and double that it will force a sub to the surface. That means after numerous hits at 12 meters will it force it to the surface. A small note, many engineers claimed many things back then, not all were true. Like the Acustic torpedo... or radar.)

back to the matter... speed of the u-boat is 4 m/s. The speed of the depth charge going down is about 3 meters per second. The turning speed of the uboat is a hard fact to find, but after some snooping around it seems that the uboat can turn 180 degress in about 110 seconds, so 90 degrees in about 55 seconds. The descent rate of the uboat is impossible for me to find :/ (this also depends on the dive plane angle and bouyancy), so I'll just assume the boat can dive at 1m/s at 20 degrees and a delay of about 10 seconds.

Those are the facts. Now lets take a look at some tactics. The IDEALway to depth charge a boat is by attacking the U-boat along its length, dropping charges (parallel in the z-axis). This way, the uboat has to turn perpendicular to avoid the dropping charges. The captain very well knows when a destroyer is overhead his uboat and will have incresed his speed to flank even before the destroyer is above him. This means he will have a speed of 8 knots by the time the charges start to drop.
Lets say the boat is at about 100 meters. This means the charges will be there in about 33 seconds. But by this time, the uboat has started to move forward and started turning to avoid the depth charges as well as started to change it's depth (going deeper to increase the descent time of the charges).

In reality this is a very complicated problem which involves intergrating in 3 dimensions with many diffrent variables and in fluid mechanicss but since it is late at night and I dont feel like breaking out the pen and paper, lets just use some simple algebra to estimate. Once the chrages are dropped it takes about 33 seconds for them to get there, but by then the boat has moved and started turning as well as started to change it's depth. If the boat is going 4m/s (8knts) it will have moved about 132 meters in 33 seconds (this is the aft of the ship). Work with me, if you think about it, the most accurate hit would closest th the center of the uboat. Why? Because the front of the uboat is turning quickly, while the aft is trailing and will be in the place of the center. Now, the boat is moving along a 3 dimensional vector (XYZ), where xy is the plane and z is the depth. This means that when the boat is turning it is also "transffering" speed from it's x axis to the y axis (with about 1.5 knst (.75 m/s) into the z when diving, 8knts*.2.. at 12 degrees). So lets take the average turning speed, which is 3.25 knts (1.65 m/s) but because the uboat will not have enough time to turn the whole turn in 33 seconds (only 1/3) lets say the speed is 1/2 from the 30 degrees angle ( .85m - x, 1.45m -y). By the time the first charge gets there the uboat will have moved, (28 meters - x, 47 meters - y, and 23 meters -z)
Because the boat is 67 meters long, The tail will be not be far enough away in the x if the charges are dropped at the nose. Using sqrt(y^2+z^2)=D, the distance to the sub is 36 meters, which is 3 TIMES the distance to do damage to the boat. Even if the captain would have simply made a turn in any direction, the boat would avoid the range of the depth charges. Now you are probably saying, "But I dont even do anything and he doesnt hit me!" Well, even the dumb ones get lucky. A good AI will try to anticipate a turn and will start turning in a specific direction to try to get the charges closer to the turning u-boat. That means the charges will be dropped to the left or to the right, and because the destroyer turns faster he will move the charges to the sides even quicker then the uboat; While the uboat keeps going foward and has move 132 meters in the x. This means the tail end is 65 meters from the closest depth charge (if not more... 132m - 67m) that is if the charge was dropped directly on the nose of the submarine (which wont happen because the best last spot to drop is the center). This is also out of range of the depth charge... in fact about 5 Times the range. What about charges in periscope depth? Well think of this, The destroyer does not want to drop charges at 12 meters depth because what damages a uboat will also damage the destroyer itself. This means the charges have to be dropped a bit deeper, say 21 meters. This means there is 6 seconds for the uboat to move and it will have moved 26 meters. This is the one and only way to ensure a direct hit. A PERFECT parallel depth charge run at periscope depth, this should damage the boat quite enough for it to surface. The only problem is that the destroyer cant tell at what depth you are so it will automatically assume that the boat will dive immediatly to try to avoid getting rammed , setting the charges even deeper. With 12 meters to work with it is extremely hard to get a decent hit, not to mention 6 meters for a CLAIMED damage to the pressure hull (which is what causes hull damage).

As you can see it is quite hard to hit a uboat with a depth charge not to mention facts such as inaccurate equipment, variation of turbulence, crews, as well as extra spacing between the pressure hull and the deck and ballast tanks, etc. I beleive this is quite correctly modeled in SH3, unlike sh2 which was a crying shame.

reumatiib
04-08-2005, 01:23 AM
but not hard to sink a sub in shallow water....no guess work about depth there. No place for a sub to hide - and very dangerous and hard for a sub to pull of fast maneuvers.
In deep water it takes quite a bit of time for barrel depth charges to reach a sub at 100 meters. In that time a sub can move off out of danger. But in shallow water it takes mere seconds for depth charges to reach a sub - no time to escape.

In the Narvik level I took the most damage by running aground on the bottom.

reumatiib
04-08-2005, 01:31 AM
in any event I had Brit depth charges going off all over me at Narvik, easily with in 36 feet, and only suffered MINOR leaks that my repair team wouldn't even bother to fix! My integ-stats dropped a few points at most. As for being hard to find I said at the beginning I was doing EVERYTHING wrong on purpose - I was moving at FLANK speed, I was making enough noise to draw every DD to me, and they indeed came!

The SH3 depth charges need to be boosted.

CCIP
04-08-2005, 01:38 AM
Well, I do think there would be a ground effect amplifying the power in shallow water, and I'm willing to bet sums on the fact that SHIII doesn't and might never model that.

Granted, the fact that escorts can be dead accurate in shallow water mostly makes up for that. I wouldn't really complain seeing how my only encounter with a DD in &lt; 30m depth ended in my death in &lt; 30 seconds, and I was dodging.
Running aground rather than being hit doesn't sound too unrealistic to me if you're running fast - and consider two more things:
repair in SHIII is over-efficient, and the sub acceleration rates are somewhat exaggarated. I think if those things are tweaked to more realistic values, you will find it much harder to avoid death at low depth. But I somehow doubt the ground effect at low depth is/will be modeled.

Pentallion
04-08-2005, 01:39 AM
History of Communications-Electronics in the United States Navy, Captain Linwood S. Howeth, USN (Retired), 1963, pages 471-478:

"Hedgehogs and mousetraps were developed which projected patterns of 30-pound charges, which exploded only by contacting the metal hulls, thereby getting closer to the targets."

emphasis mine.

Now when you consider how exponentially harder it would have been to actually hit the target as compared to just coming within, say, 30 yards of the target, you gotta figure they had a pretty darn good reason to actually change the way DC's detonated.

That reason being it was a waste of time when a DC was a near miss that only caused so much noise the target could escape. Only a direct hit was even worth detonating the DC for!!!

Case closed.

Pentallion
04-08-2005, 01:52 AM
Adding to Mloddy111's excellent analysis, consider the following fact about ASDIC: It came out in a horizontal cone like this:

How sonar works (http://www.aircombat.net/files/sonar%20works.jpg)

Notice in that (albeit lousy artwork by me) diagram that if you were at 50 meters, the DD's sonar would pick you up all the way from @2000 meters away right up to about 150 meters in front of him. At that depth, you literally have to dodge DC's at the very last seconds. But you still have the last 150 meters of distance in which to manuever while he can no longer see you because his pings haven't descended that quickly in that short a range.

But at 100 meter depth, you're under his sonar at about 600 meter range. So if a sub skipper starts his evasive manuever at THAT point, then add that distance to the distance in which the DD must GUESStimate your subs position. In addition to descent time for the DC's.

Finally, look at a sub at 200 meter depth. ASDIC loses it at 1200 meter range or closer. How long will it take the DD to even reach the subs last known location let alone calculate all the possible directions the sub could have turned and GUESStimate where the sub is now in order to drop DC's.

And on top of all that, the DC's didn't do a whole lot of damage in the first place unless they were especially close.

This whole argument already has been hashed out over at subsim.com's mods forum. The DC's are fine just the way they are. One fellow wants to increase DC descent times. Even that isn't realistic, but he gets more fun out of it.

alanschu
04-08-2005, 02:36 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>in any event I had Brit depth charges going off all over me at Narvik, easily with in 36 feet, and only suffered MINOR leaks that my repair team wouldn't even bother to fix! My integ-stats dropped a few points at most. As for being hard to find I said at the beginning I was doing EVERYTHING wrong on purpose - I was moving at FLANK speed, I was making enough noise to draw every DD to me, and they indeed came! <HR></BLOCKQUOTE>

You seem to be the only one who has this problem then. I just tried it and died in no time.

Of course I wasn't pulling out the ruler and confirming that all the depth charges were within 36 feet like you did (must be a whiz with that external camera....I can't tell anything like that).


As my link said, depth charges weren't a huge threat to subs unless they were painfully close...even with the 600 lb one that the brits don't actually use. If it takes 5 meter distance from a 600 lb one, how close does it have to be with a mere 300 lb one that the brits are dropping on you? Probably has to **** near be on the hull to do any real damage.

Pr0metheus 1962
04-08-2005, 02:58 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by alanschu:
I think reumatiib only plays in the early part of the war (which is also when those 600 lb depth charges he talks about didn't even exist). Seriously, go play the 1943 campaign. <HR></BLOCKQUOTE>

Actually, I'm finding that the game seems a lot tougher after installing the 1.2 patch. I just took a boat up the Bristol channel, and I got into serious trouble up there, and this was in 1940. I survived, but only because I was lucky: they set the depth wrong on the only charge that got within 5m of my sub, so it sailed harmlessly by the rudder as I was gritting my teeth and praying.

alanschu
04-08-2005, 03:15 AM
Hehehe, I have met up with some fun encounters when getting curious about the harbours.


Although I found out the hard way that unfortunately the harbours are a little empty http://forums.ubi.com/groupee_common/emoticons/icon_frown.gif

Oh well....I sunk a Fiji in the Loch Ech (or whatever) and a Dido in Scapa Flow, my first two warship kills http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif (not counting the odd trawler/corvette/elco. It was great to see them panic as I lined up two torpedoes at high speed, 3-4 foot depth on impact. Looked cool when they sat at the bottom, but still burned above the waterline because they were too tall to sink fully http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

I'm also beginning to agree with you about depth charges having a bit of randomness to them. I took some minor damage from a couple that seemed to be farther out than a couple of other ones....but maybe my crew was a too scared to report it exactly when it happened http://forums.ubi.com/groupee_common/emoticons/icon_razz.gif

I did have one bounce off my hull and blow up...which caused huge flooding and killed me dead.

crpcarrot
04-08-2005, 05:18 AM
i remember a nother thread either here or at subsim where the machanics of the torpedo hits was being duscussed. it seemed like all hits did not produce the same amount of damage/force maybe DC explosions also have this factor of randomness.

dmm_u333
04-08-2005, 05:52 AM
According to 'Ali' Cremer (Commander U-333), the tommy depth charges indeed had the power to cause major damage (and thus kills) but (at least in the early part of the war i.e. 1939-1942), they set the detonators to trigger too shallow. The Uboat commanders would simply go lower (&gt;100m) to avoid.
It was not until interrogation of uboat crews that they realised this and started setting the charges for lower depths.

It is fair to assume therefore that there is nothing wrong with the current SHIII depth charge 'power' settings?