A study in IJN destroyers

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mescal
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A study in IJN destroyers

Post by mescal » 18 Mar 2009 14:07

Hello,

After the cruisers,
after the battleships,
I'm now happy to be able to post a similar set of charts dealing with the Imperial Japanese Navy destroyers.

First of all, I would like to state that I'm greatly indebted to Allyn Nevit and his work compiled at http://www.combinedfleet.com/lancers.htm

The color code I use is the same as in the previous threads, as is the location codes
the color code are the same as usual :
green : available
red : sunk
orange : combat damage
yellow : noncombat damage
purple : repair/refit/... = unavailable
light blue : training
brown : withdrawn from active service
grey : building

CH : China (Shanghai to Yellow Sea)
CP : Central Pacific ("PH" is Pearl Harbor)
SP : South Pacific (including ships based at Truk)
NP : North Pacific (Hokkaido to Aleutian)
EI : East Indies (Indonesia - Singapore - malaya)
VN : Viet Nam / South China Sea (based at Cam Ranh)
HW : Home Waters (from Formosa to Honshu and Korea)
PI : Philippines
IO : Indian Ocean


Part I : The Minekaze, Kamikaze and Musuki Classes

These are the oldest destroyers the IJN had at the beginning of the war. The first two of those classes were not equipped with the 'Long Lance' but with the previous 21" torpedoes.

Minekaze class :
built 1920-22 , 1350 tons
13 ships,
8 sunk during the war, 7 of them by submarines and one by air power
5 survived, 3 of them had previously been reclassified as target / training / reserve ships

Kamikaze class :
built 1922-23, 1400 tons
9 ships,
7 sunk, 4 of the by subs, 2 by air power and one by shore battery
2 survived, one of them in a damaged and unrepaired state.

Mutsuki class
built 1926-27, 1770 tons
12 ships,
12 sunk, 1 one them by sub, 9 by air power and 2 by ships
IJN_DD_11.jpg
IJN_DD_12.jpg
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Re: A study in IJN destroyers

Post by mescal » 18 Mar 2009 14:19

Part II : The Fubuki, Akatsuki and Hatsuharu Classes

These were the first modern destroyers in the IJN inventory.

Fubuki Class :
built 1928-31, 2090 tons
20 ships,
one sank in an accident before the war and 18 during the war, 6 by subs, one by mine, 8 by air power and 3 by ships

Akatsuki Class :
built 1932, 1980 tons
4 ships,
3 sunk during the war, by submarines and on by ship.

Hatsuharu Class :
built 1933-35, 1800 tons
6 ships,
6 sunk during the war, one to submarine, one to mine and 4 to air power

IJN_DD_21.jpg
IJN_DD_22.jpg
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Re: A study in IJN destroyers

Post by mescal » 18 Mar 2009 14:29

Part III : The Shiratsayu, Asashio and Kagero

These were the last 3 classes completed before the beginning of the war. Kageros were the main fleet destroyers at the time of Pearl Harbor.

Shiratsayu Class :
built 1936-37, 1980 tons
10 ships,
one lost to an accident during the war (collision)
nine lost to enemy action : 5 to submarines, 1 to air poser and 3 to ships

Asashio Class :
built 1937-39, 2370 tons
10 ships,
10 lost during the war : 2 to submarines, 4 to air power, 4 to ships

Kagero Class :
built 1939-41, 2490 tons
18 ships,
17 lost during the war : 3 to submarines, 2.5 to mines, 6.5 to air, 5 to ships

IJN_DD_31.jpg
IJN_DD_32.jpg
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Re: A study in IJN destroyers

Post by mescal » 18 Mar 2009 14:37

Part IV : The Yugumo, Akizuki and Shimakaze Classes

These were classes completed during the war. Shimakaze is a one-ship class, arguably the best destroyer of the IJN.

Yugumo Class :
built 1941-44, 2520 tons
20 ships,
20 lost : 5 to submarines, 1 to mines, 10 to air power, 4 to ships

Akizuki Class :
built 1942-45, 2700 tons
12 ships,
7 lost, 1 to submarines, 1 to mines, 2 to air power and 3 to ships
5 survived the war, two of them in a damaged and unrepaired state.

Shimakaze Class :
built 1943, 3050 tons
1 ship
lost to air power

IJN_DD_41.jpg
IJN_DD_42.jpg
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Re: A study in IJN destroyers

Post by mescal » 18 Mar 2009 14:43

Part V : The Matsu Class

Sometimes splitted in two classes (Matsu & Tachibana classes), these were late war and smaller ships than previous ships. Most of them saw few action because of lack of fuel.

built 1944-45, 1530 tons
32 ships,
9 lost during the war, one to sub, 1 to mines, 4 to air power, 3 to ships
23 survived, 6 of them in a damaged and unrepaired state.
IJN_DD_5.jpg
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Re: A study in IJN destroyers

Post by mescal » 19 Mar 2009 17:19

Now that the raw data are available, it's time to begin the analysis step.

First a few remarks have to be done regarding the charts of the previous posts :

* There is nothing new in the data here. A lot has alredy been said about the IJN.
But AFAIK these data are not present on this board, and some synthetic tables and charts are worth a lot of pages of confused discussions.

* "b" starts at the beginning of the war for all ships not in commission on 7 dec 41. It implies that some ships are tagged 'b' in 41/42 whereas their keel was actually laid down later. It's an arbitrary choice I made since I lacked some data regarding the true date of the beginning of the building. I judged it acceptable since I'm not investigating the building time -- all I'm interesting in is the fact that before commissioning, the ship is out of the scope of my analysis.

* Initial training is counted as available time for a given ship. The rationale behind this is that most cases are late-war commissionning and, as the war went on, the Japanese were more and more desperate and thus more and more ready to sent under trained planes and ships to the fight. I recognize it can argued

* Some ships spent a lot of time making round trips between Japan and Truk or Japan and Singapore, never staying for a full month at a place. In such case I tagged one every two month with one label and the other month with the other label. It's an unpleasant approximation if we want an analysis of the movement of said ship, but it enables to smooth the data for more aggregated views, reflecting relatively correctly that this ship spent half of the time in one locaiton and the other half on the other location.

* Unavailability is underestimated, as I do not take into account the unavailabilities that lasted less than one month, and the IJN seems to have often used short-term upkeeps and overhauls. It i compounded by the distance and travel time from the war zones to the naval bases during the first half of the war.
One last factor is that alot of the destroyers listed as available in Japanese home waters in 1945 were actually not available due to lack of fuel. Since I had no data regarding the actual fuel stocks, I chose to consider that they wore seaworthy -- and that from US point of view, they could be used.

* As always, all of these data are to the best of my knowledge. I do not pretend they are hard facts.

OK, now we can go on with the stats and analysis.

Part VI : Analysis

I will also split this part in as many sub parts as necessary.
Let's say as a disclaimer that all interpretations are mine -- and that I would be happy to discuss, comment or integrate all ideas, comments and remarks you may want to do.


1) Raw Numbers :

The first chart is a simple summary of the number of DDs afloat vs DDs under repair vs DDs sunk
IJN_DD_lines.jpg
It highlights the huge attrition rate the IJN was facing, and the fact that the new contructions were completely incapable of compensating this attrition.
This can be seen in the following chart, which compares the number of sinking to the number of newly commissioned ships on a monthly basis.
IJN_DD_sink_vs_comm.jpg


Next part coming soon ...
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Re: A study in IJN destroyers

Post by mescal » 20 Mar 2009 15:23

Still nobody to comment ? ...

Anyway, I'm still not tired of posting :lol:


2) Geographic deployment and analysis by classes

I have a grand total of 3290 month.DD for the IJN during the war. Among those, 597 were months of refit/repair.
This leaves 2693 month.DD for the IJN to allocate to all its tasks and areas.

Below is a chart of the geogrpahic deployment by classes
Under each geographic column header are both the total number of month.DD spent in this area over the war and the percentage it represents for this class.
For example : the ships of the Kamikaze class spent 35 months in the North Pacific, which represent 15% of the 239 available months for the Kamikaze class.
The unavailability is computed as U/(U+avail) : for the Mutsuki class : 15% = 39/(39+216). Note that the 30% unavailability for the Minekaze class is artificially high and comes from the fact that two ships very put in the reserve for training/target practice very early -- and they are labelled as U in my database.
IJN_DD_stats_class.jpg
So the main workhorses of the fleet were (not surprisingly) the Kageros and Fubukis, with Yugumos & Mutsuki as distant followers. (I do not take Minekaze and Kamikaze into account here, as they were old DDs, outdated for fleet action).

What appears regarding the geographic deployment is that the South Pacific was the first area where IJN deployed its DDs, with the Home Waters as close second.
"East Indies", "Central Pacific", "Philippines" and "North Pacific" are secondary nonnegligible areas.
Indian Ocean, China and "Viet-Nam" are clearly backwaters.

It's however interesting to note that the classes which around half of the weight of the Home Waters investment are either the late war Matsus, commissionned when there were no other waters any more in the empire, and the old Minekaze, relatively unfit for first line duty.
This should lead us to conclude that the single main area of effort for the IJN DDs was the South Pacific. Actually, it was the focal point of no less than 6 classes out of 12 (I do not count the singl Shimakaze as a 13th class for statistical purposes).

Another relatively surprisingly fact are the 283 month.DDs spent in the North Pacific. It seems like a real overinvestment in meaningless backwaters, and that some of these efforts could have yield greater rewards elsewhere.


However, these are agregate data over the whole war and do not show the evolution of these deployments along the course of the war.


3) Geographic deployment : a 'dynamic' approach

Below is a chart of the number of DDs per location on a monthly basis.
The 'backwaters' (IO, VN & CH) are not shown so as not to overload the chart.

[chart DD_line_area here]
IJN_DD_line_areas.jpg
So we do not have the information by ship classes, but we now have a pseudo-dynamic view of the succession of areas of effort of the IJN.
We retrieve the well-known sequence of the events of the beginning of the war : conquest of the Philippines (Light blue initial peak) & Central Pacific in Dec 41, immediately followed by an effort in the East Indies (purple peak). Then come operations AL & MI (yellow peak) ... followed by the main effort in the south.

Some other interesting patterns :
* The purple-yellow-green sequence of May-june-July 44 is actually mainly the same fleet -- the one which fought the Marianas Turkey Shoot, showing the concentration in forward base, move towards mariannas & retreat.

* The absolutely massive reaction to the Guadalcanal landings in august 42, with 45 ships transfered in less than one month. IJN staff is often criticized because it did not recognize it as the Decisive battle. However we can see here that the threat was not overlooked, and that the assets, at least regarding DDs, were not sent piecemeal.

* It's only the Hailstone operation that put an end to the presence of the IJN DDs in the South Pacific.

* the Green tail is of relatively small meaning, owing to the lack of fuel. Many of those ships were more floating AA batteries than DDs.


Overall, what is impressive here is the concentrated use of the IJN DDs in one area for a short period (well, it lasted longer in the Solomons, but not for a lack of will from IJN staff).
(note that the chart is not normalized, so even if the Philippine peak of 44 is lower than the Philippine peak of Dec 41, it represent a far higher proportional investment).
Actually, we can also see it the other way : IJN did not have enough assets to do all its jobs, and was compelled to strike short-term concentrated blows -- leaving the rest of the Empire relatively lightly protected.



More to follow ....
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Re: A study in IJN destroyers

Post by mescal » 23 Mar 2009 15:52

Is anybody out there ?
(if you find my posts boring, you can tell it, I'll try to improve my standard ) :D



Another way of looking at the deployment sequence of the IJN ships is to divide the 45 months of the war into shorter periods, and analyse both the deployment within each period and the evolution from one period to another one.
In this regard I decided to use the 3 periods (or "Phases") which had been identified beforehand in War Plan Orange -- since the war proceeded pretty much as planned by the USN.
These three phases can be named : Japanese assault, attritional reconquest and siege of Japan.
However, given the length of the secon period, I also divided it in two sub-periods, the first one being the fight in the Solomon Islands and the second going until the Philippine landings.
More precisely in the chart below, we have :
Period 1 = from 7 Dec 41 to 30 June 42 (Battle of Midway)
Period 2 = from 1 July 42 to 31 Dec 44 (Mindoro landings)
period 2.1 = from 1 July 42 to 30 Nov. 43 (Empress Augusta Bay)
period 2.2 = from Dec 43 to Dec 44.
period 3 = from 1st January 1945 to 15 August 1945

(the Lingayen landing would have been a better milestone than Mindoro, but since it occured at the beginning of the month, it would introduced a bias in my monthly satistics).
IJN_DD_stat_per_cam.jpg
This charts represent the proportional investment in each geographic area by period. It thus does not take attritin into account :
The first period represents 621 month.DD available; the second 1818 and the third 253.

These data can be detailed in the table :
IJN_DD_stats_periods.jpg

The main effort during phase one is clearly south, to invade enemy valuable territory (PI + EI + VN + SP = 58%), while secondary efforts are made to neutralize beforehand enemy counterthrust (CP + IO + NP = 27%).
Losses amount to a small 7 ships (one per month), while unavailability is low at 11 ships/month.

The second phase shows far higher attrition and more focus on one single region.
During period 2.1, IJN invested more than half of its DDs in the SP, almost disappearing from East Indies or the Philippines. However, the 15% invested in the North Pacific remains intriguing.
The losses grew to 2.7 ships per month, and the unavailability doubled to 20 ships in yard each month.

Phase 2.2, after the loss of the Solomon Islands saw a return to a relativley more balanced deployment -- and numerous ships back in Home Waters, the beginning of the great retreat.
Losses however remained high, and even grew higher, with 4.5 ships lost each month. However, these losses were not evenly distributed over the period, 22 of them occuring in only two months.
It's interesting to note that the unavailability rate fell below the one of the first part of the war. Since I do not have a distincion between 'Unavailable' and 'Unavailable due to enemy action', it's not clear whether this fall came from the fact the the IJN had so few assets that it could not spare time for refit or simply because by that time the US had sent enough ordnance to sent a target to the bottom and not just damage it.
Actually, I think that both explanations are true.


Phase 3 saw almost all surviving ships back in home waters -- and far away from their fuel supply. "Availability" here meant more and more "seaworthy if oil can be found".
Among the 253 month.DD "available", 149 came from the Matsu-class small destroyers (and 12 from the old Minekaze). This gives us a mean of eleven "fleet DDs" available each month, showing that, even if fuel had been available, any fleet could not have had any serious DD scren).
(Only 6 of all the DDs existing on 7 dec 41 survived the war.)


And that's it for now.
(Well, I still have some data to analyse, but it's growing harder to find motivation to type the posts without feedback or interaction with other.)
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Re: A study in IJN destroyers

Post by daveh » 23 Mar 2009 18:19

While the Pacific is not my main interest this type of post makes it much easier to look at aspects of the Pacific war and so tempts one to go into greater detail. The work you have done has presented a lot of information but it is in a clear and readily understandable form. As I have just started to produce various graphs/charts/ tables for my own area of interest I appreciate the time and effort you have put in.

The lack of feedback may be due to the amount of information you have presented..it does take time to absorb and analyise.

As far as I am concerned Keep up the good work!!!

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Re: A study in IJN destroyers

Post by HenryW » 24 Mar 2009 02:21

Very interesting. I've enjoyed your posts. Please keep posting.

Great work!

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Study? What study?

Post by cstunts » 24 Mar 2009 14:38

Hello,

"Study"? What study? This is just extant data reconfigured to look pretty. It might prove informative to the novice, but it is no sense a "study" of IJN destroyers, as it draws no conclusions and sheds no new, or worthwhile historical light on anything. A series of charts and graphs and masses of statistics do not make a "study" and provides no "analysis" either. THAT requires some creative thinking, and this software-mongering exercise, like many alt-history discussions clogging these boards nowadays, exhibits anything but thought...

On the positive side: there is vast room for improvement, should any ideas inadvertently wander in. :)

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Re: A study in IJN destroyers

Post by LWD » 24 Mar 2009 17:45

A rather rude statment of opinion posted in such a way as to invite a hostile rather than a considered response. The charts are at least useful and have resulted in postive discussion. The previous post was not and is not likly to.

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Re: Study? What study?

Post by mescal » 24 Mar 2009 19:27

cstunts wrote:Hello,

"Study"? What study? This is just extant data reconfigured to look pretty. It might prove informative to the novice, but it is no sense a "study" of IJN destroyers, as it draws no conclusions and sheds no new, or worthwhile historical light on anything. A series of charts and graphs and masses of statistics do not make a "study" and provides no "analysis" either. THAT requires some creative thinking, and this software-mongering exercise, like many alt-history discussions clogging these boards nowadays, exhibits anything but thought...

On the positive side: there is vast room for improvement, should any ideas inadvertently wander in. :)
Hello,

Perhaps the word "study" is not the best to describe what I'm doing. I agree, I didn't spend 2 hours thinking about each word of the title.
I apologize if it make the topic appears as a "Research" topic, it was not intended (actually, had I thought I was bringing new knowledge, I would have labelled it "Research into ..." or "Advances from new sources ..." -- and sent it to a professional review first).

I'm NO historian, and I do not claim to bring new info from new sources -- I do not have access to anything like first hand sources.
I did all this work (and it takes a lot of time) as an amateur, on my spare time, and posted it here because I felt synthetic presentations on this topic were lacking, and it thus could interest some people (acting on the principle that "All knowledge not shared is lost").

I hoped that anyone with more light and analyses on this topic woud make some valuable post in this thread, to complete, argue, refute, develop... the data I formated.
Actually, in a perfect world, the "Study" would be the whole thread following my intial posts bringing in data.
Olivier

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Re: A study in IJN destroyers

Post by Eugen Pinak » 03 Apr 2009 12:59

mescal
Perhaps the word "study" is not the best to describe what I'm doing.
It's actually exactly the word - see here: http://www.thefreedictionary.com/study
a. A work, such as a thesis, that results from studious endeavor.
b. A literary work on a particular subject.
c. A preliminary sketch, as for a work of art or literature.


As for cstunts' comment - there are always be people, why just like to say "you're doing it wrong". It doesn't mean that you're actually doing it wrong - they just love to say it. After all, it's much easier, than to do something yourself ;)
I'm NO historian, and I do not claim to bring new info from new sources -- I do not have access to anything like first hand sources.
Just as Convay, Jane's, etc. - yet nobody claim, that this data-books are useless.

As for me, I found your work very useful. For example, your "availability" stats on "Asasio" class make me think, that their problems with turbines were not completely cured. Thank you.

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Re: A study in IJN destroyers

Post by Larso » 03 Apr 2009 14:25

I found it all very interesting. I enjoy toying with orders of battle myself, making lists of units and so on, so I appreciated your efforts!

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