RE: damagelethality of depth charges (Full Version)

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bradfordkay -> RE: damagelethality of depth charges (7/4/2006 6:58:54 AM)

"Should anyone be interested the total number of attacks delivered with whichever ASW weapon is noted in the TROMs for the IJN subs."


And how did they get these reports from the sunken subs?




spence -> RE: damagelethality of depth charges (7/4/2006 1:44:01 PM)

    In rare cases the escorts picked up a survivor who identified his ship.  In most it was a post-war correlation of an ASW ships AAR (particularly the sighting of wooden or cork debris, oil and/or human remains with the "disappearance" (from the IJN perspective) of a sub operating in a certain area.  In some cases the identity of the sub sunk is noted as "probably the I-#/RO-#".  As an example of the situation in such cases though one might ask the question:
"What subs did the IJN lose in the Gilbert Islands in Nov '43?" 
a) I-#
b) I-##
c) I-### 
d) RO-#
e) RO-##
f) ALL OF THE ABOVE (the correct answer) 




spence -> RE: damagelethality of depth charges (7/4/2006 4:04:01 PM)

quote:



IJN Submarine I-12


--------------------------------------------------------------------------------

Date of Action: 13 November 1944
USCG Unit(s) Involved: USS Rockford, PF-48, a Coast Guard-manned frigate [in concert with US Navy's USS Ardent, AM-340.]
Sinking/Capture/Assist? Probable sinking, credit shared between Rockford and Ardent.
Location of event: 31'- 55" N x 139' - 45" W
Credit by US Navy? Yes, probable sinking (see below).
Enemy warship's Commanding Officer: ??
Enemy casualties: 114 officers and men
USCG casualties: None.
Misc:

Details/Updates:

The USS Ardent (AM-340) and the Coast Guard-manned frigate USS Rockford (PF-48) escorted a six-ship convoy from Honolulu to the United States' mainland in November 1944. As they approached the midway point of the voyage, the Ardent made a sonar contact ahead of the convoy. She began plotting the contact and made two hedgehog attacks with negative results. The Rockford then made a "well conducted attack" with a 13-charge hedgehog pattern. Fifteen seconds later the crew heard three distinct hedgehog detonations and four minutes later they heard numerous underwater explosions. Water and air bubbles were then observed "boiling" on the surface, along with diesel fuel and debris, including teak deck planks (one with Japanese builders' inscriptions), ground cork, pieces of a vegetable crate covered with labeling in Japanese, pieces of varnished mahogany with tongued and grooved material, and one piece of smoothly finished wood from instrument case, with loose screws around the edges, and inscribed with Japanese writing.

The subsequent analysis concurred that three hedgehog charges detonated against the submarine, causing its destruction. Both warships were given equal credit in the probable destruction of a Japanese submarine. The only Japanese submarine operating along the west coast of the United States at that time was the I-12, which had attacked and sank the SS John A. Johnson on 30 October.

Technically their claim remains unconfirmed as the sinking was not corroborated by Japanese documentation captured after the war. Japanese sources indicate that the submarine was active through December and is listed as having been lost in January, 1945 from unknown causes. Nevertheless, due to the clear sonar contact, the accuracy of the attack including three hedgehog explosions, and the debris recovered, it is most probable that the Rockford and the Ardent did, in fact, sink the I-12.

Click here for a history of the USS Rockford.


--------------------------------------------------------------------------------

Sources:

Memo, COMINCH, United States Fleet, Incident No. 7282, "Analysis of Anti-Submarine Action By USS Rockford (PF-48) and USS Ardent (AM-340)."

W. J. Holmes. Undersea Victory: The Influence of Submarine Operations on the War in the Pacific. Garden City, NY: Doubleday & Company, Inc., 1966, p. 413.


--------------------------------------------------------------------------------

[Historians' Office] [WWII Combat Victories]

[USCG Home Page]
Added: December 2001




quote:

30 October 1944:
North Pacific. Cdr Kudo attacks a convoy enroute from San Francisco to Honolulu. At 2110, the I-12 hits the 7,176-ton American "Liberty" ship JOHN A. JOHNSON with two torpedoes. The 1-12 attacks but misses another transport.

The JOHNSON is abandoned and breaks in half. The I-12 surfaces and shells both sections of the ship. They both sink at 29-36N, 141-43W. The I-12 rams a lifeboat then makes its way among the JOHNSON's lifeboats spraying the survivors with machine guns and pistols killing six men. That day, the remaining survivors are picked up by the USS ARGUS (PY-14) on patrol out of San Francisco.

20-31 December 1944:
The I-12 reports sinking a transport and a tanker in mid-Pacific.

15 January 1945:
Cdr Kudo sends a message that he has been spotted by the enemy N of the Marshalls. This is the last signal received from the I-12.

31 January 1945:
Presumed lost with all 114 hands in the mid-Pacific. The cause of the I-12's loss remains unknown.*

10 August 1945:
Removed from the Navy List.


________________________________________________________________________________________________
*Some sources credit the USCG cutter ROCKFORD (PF-48) and the minelayer USS ARDENT (AM-340) with sinking the I-12 in the Central Pacific on 13 November 1944, but Cdr Kudo's last message belies that claim.

Author's Note: Special thanks for help in preparing this TROM go to Dr. Higuchi Tatsuhiro of Japan.
– Bob Hackett


There are problems figuring out what really happened - especially with ASW. The above are first; the official US Coast Guard Historian's record of a combat victory in the Pacific War and second; the reconstructed TROM of the I-12 from Combined Fleet. Presumably, copies of the messages recieved from I-12 subsequent to its alledged sinking do exist. But the physical evidence collected by the ROCKFORD combined with the recorded 3 hedgehog detonations makes it seem very likely that somebody died that day in that location.




Cmdrcain -> RE: damagelethality of depth charges (7/11/2006 3:29:40 AM)

quote:

ORIGINAL: jwilkerson


quote:

ORIGINAL: Drex

Has anyone ever sunk a sub with one depth charge hit? It seems to me that if a DC "hit" a sub the explosion would damage the shell bad enough to cause massive flooding but in WitP it seems to take 2 or more "hits" or a series of a hit and near misses to sink the sub. So how close does the DC have to be for it to effective to sink? or is that possible in this game?


I just LOST a sub to 1 depth charge hit.

On the other hand, I taken 25 hits and survived.

Note that in the new 1.7.9.5 system, and "hit" is not necessarily a "hit" .. some "hits" (most?) are "rattles". The 25 were probably all "rattles" .. the one that sank with one hit .. was clearly a "real" hit. One "real hit" should be enough if it is the right hit ... though many misses ... should be quite normal.

In my current "test" game against the AI ... I'm in Feb 44 and I've lost 24 US subs (tracking pretty darn close to historical rate) ... 14 to air and 10 to surface ... and I am using them "very" aggresively ( i.e. historically ) they are camping all over the home islands and the SRA.



With 1.8x Do "rattles" do any type of damage at all?

I've noticed some are asterisked * ** ***
as if the sub was getting very close near misses.

Seems to me for realistic combat, very close near misses should give damage at least a point or so of system damage to sim the burst pipes etc and so
enough close near misses would accumulate enough Sys damage to have a sub return to port for repairs.

Subs did return to ports without getting hit direct but suffering damage from close rattling near misses that required repairs..

So do near misses like those with asterisks give damage?

Or are all near misses even those sating taking on water are just eye candy?








el cid again -> RE: damagelethality of depth charges (7/11/2006 4:59:35 AM)


quote:

ORIGINAL: bradfordkay

"Should anyone be interested the total number of attacks delivered with whichever ASW weapon is noted in the TROMs for the IJN subs."


And how did they get these reports from the sunken subs?


The author of War Benieth the Sea is explicit: we did not get reports from sunken IJN subs. He credits two by name with exceeding the time underwater record set by USN - and one German sub - but says it is "certain" other IJN subs also broke the record - but didn't survive the war so we could read their logs.




el cid again -> RE: damagelethality of depth charges (7/11/2006 5:02:37 AM)


quote:

ORIGINAL: Cmdrcain

quote:

ORIGINAL: jwilkerson


quote:

ORIGINAL: Drex

Has anyone ever sunk a sub with one depth charge hit? It seems to me that if a DC "hit" a sub the explosion would damage the shell bad enough to cause massive flooding but in WitP it seems to take 2 or more "hits" or a series of a hit and near misses to sink the sub. So how close does the DC have to be for it to effective to sink? or is that possible in this game?


I just LOST a sub to 1 depth charge hit.

On the other hand, I taken 25 hits and survived.

Note that in the new 1.7.9.5 system, and "hit" is not necessarily a "hit" .. some "hits" (most?) are "rattles". The 25 were probably all "rattles" .. the one that sank with one hit .. was clearly a "real" hit. One "real hit" should be enough if it is the right hit ... though many misses ... should be quite normal.

In my current "test" game against the AI ... I'm in Feb 44 and I've lost 24 US subs (tracking pretty darn close to historical rate) ... 14 to air and 10 to surface ... and I am using them "very" aggresively ( i.e. historically ) they are camping all over the home islands and the SRA.



With 1.8x Do "rattles" do any type of damage at all?

I've noticed some are asterisked * ** ***
as if the sub was getting very close near misses.

Seems to me for realistic combat, very close near misses should give damage at least a point or so of system damage to sim the burst pipes etc and so
enough close near misses would accumulate enough Sys damage to have a sub return to port for repairs.

Subs did return to ports without getting hit direct but suffering damage from close rattling near misses that required repairs..

So do near misses like those with asterisks give damage?

Or are all near misses even those sating taking on water are just eye candy?







It appears to me that near misses cause increase in ops points. They also are stated to cost fuel points. Both are realistic and better modeling than I expected.




Cmdrcain -> RE: damagelethality of depth charges (7/11/2006 12:38:56 PM)

quote:

ORIGINAL: el cid again


quote:

ORIGINAL: Cmdrcain

quote:

ORIGINAL: jwilkerson


quote:

ORIGINAL: Drex

Has anyone ever sunk a sub with one depth charge hit? It seems to me that if a DC "hit" a sub the explosion would damage the shell bad enough to cause massive flooding but in WitP it seems to take 2 or more "hits" or a series of a hit and near misses to sink the sub. So how close does the DC have to be for it to effective to sink? or is that possible in this game?


I just LOST a sub to 1 depth charge hit.

On the other hand, I taken 25 hits and survived.

Note that in the new 1.7.9.5 system, and "hit" is not necessarily a "hit" .. some "hits" (most?) are "rattles". The 25 were probably all "rattles" .. the one that sank with one hit .. was clearly a "real" hit. One "real hit" should be enough if it is the right hit ... though many misses ... should be quite normal.

In my current "test" game against the AI ... I'm in Feb 44 and I've lost 24 US subs (tracking pretty darn close to historical rate) ... 14 to air and 10 to surface ... and I am using them "very" aggresively ( i.e. historically ) they are camping all over the home islands and the SRA.



With 1.8x Do "rattles" do any type of damage at all?

I've noticed some are asterisked * ** ***
as if the sub was getting very close near misses.

Seems to me for realistic combat, very close near misses should give damage at least a point or so of system damage to sim the burst pipes etc and so
enough close near misses would accumulate enough Sys damage to have a sub return to port for repairs.

Subs did return to ports without getting hit direct but suffering damage from close rattling near misses that required repairs..

So do near misses like those with asterisks give damage?

Or are all near misses even those sating taking on water are just eye candy?







It appears to me that near misses cause increase in ops points. They also are stated to cost fuel points. Both are realistic and better modeling than I expected.




Well not direct damage then, but if fuel and Ops (I take it time on station like 45/180 becoming 60/180
say ..just an example... and so reducing length could stay before a RTB(return to base) That is as good, means all my near misses on USA subs at choke points by my ASW fleets is affecting them [:D]





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