Combined Historical Scenario - Ship Data

[Don Bowen]

I am nearing completion on the re-work of the Japanese ship classes. I have temporarily bypassed the remaining cruisers and destroyers, where there are some questions, to move through the rest of the ships. I have attached a list of the changes so far.

Many more items need work and a complete review is needed to catch the typos and thinkos.

For the large number of new merchant ship classes, I have worked up some fanciful numbers for Capacity, Maneuver, and Durability. The speed numbers are all good but may be reduced as has been discussed in the forum. Fuel and endurance are have correct and half otherwise. For armaments, I used the Matrix standard 2x3" and 2xMG unless I had some specific data to do otherwise. I will put together a list of the major parameters and post them sometime this weekend.

Don

[CobraAus]

I just found this top site full of info and art/photos
http://navysite.de/ships/
below id Protius Fulton class
Cobra Aus

[Ron Saueracker]

ORIGINAL: CobraAus

I just found this top site full of info and art/photos
http://navysite.de/ships/
below id Protius Fulton class
Cobra Aus

This is their Polaris missile tender config.

[Tankerace]

So what, would that be the 6/63 refit? [:D]

[Andrew Brown]

ORIGINAL: Ron Saueracker
This is their Polaris missile tender config.

Hmmmmm. Polaris - finally an easy way to kill the KB...

[Lemurs!]

Hi Don,

The Atago and Takao were refit in August-September '38 with quad torp tubes, and the 4 4.7" guns were replaced with 8 5" AA guns.

The Maya was refit in January '42 with the 4.7" guns removed and 8 5" AA guns added. No other changes. The Chokai should have the same update date as the Maya because there was no reason it could not have been updated. The ship was a flagship and it's admiral never took the time out to have it refitted.

I don't want to say anything bad but the Japanese Cruiser ops book seems a little spotty in it's research.

Mike

[Don Bowen]

The majority of the work on Japanese Transports is done. The 2999 available Japanese ship slots are almost all used up. I have about 2-dozen empties (and 200 more identified merchants not yet in). I want to wait on using up the last few slots until all this has been reviewed. Then I'll use up any remaining empties for the largest missing merchants.

This is Transports, see the next post for Cargo Ships.

[Don Bowen]

Here's the AKs

[bstarr]

Outstanding work. I can't wait to see the finished product..

Hey, here is one more site that I was getting a lot of info from on US AKs. I believe I've already listed the others.

http://www.usmm.org/ships.html

I also have an appendice which lists which Navy ships belong to which categorys, specifically the AKAs and APAs. If you don't have a list I can send it your way; it would certainly be easier to look down a numerical designation list like they have at HazeGrey. Let me know if you need it and I'll send it your way. I'll need to email it though, since it would be several scanned pages.

I also found a good site on Canadian built ships, but I found it on the work computer and have been unable to find it at home. I did discover that early Canadian-built ships (Forts and Parks) were Coal burners. I figured this would make a difference on the endurance and maybe their capacity as well.

[Marc]

ORIGINAL: Lemurs!

Hi Don,

The Atago and Takao were refit in August-September '38 with quad torp tubes, and the 4 4.7" guns were replaced with 8 5" AA guns.

The Maya was refit in January '42 with the 4.7" guns removed and 8 5" AA guns added. No other changes. The Chokai should have the same update date as the Maya because there was no reason it could not have been updated. The ship was a flagship and it's admiral never took the time out to have it refitted.

I don't want to say anything bad but the Japanese Cruiser ops book seems a little spotty in it's research.

Mike

Mike,

sorry but in my opinion that is not true.
You are right with the quad torpedo tubes in 1938 but the 5" turrets should have been installed on Atago and Takao but "a lack of funds initially prevented the replacement. The change was not made until March (Takao) and April (Atago) 1942... However some preparatory modifications to the support platforms and magazines were executed in 1939."
There are 10 pages in the book just describing the upgrade of Takao and Atago in 1938-39. If you want I can scan them for you.

The Maya did NOT receive the 5" guns in January 1942. The old 4.7" guns were removed during her conversion to an AA cruiser!
"The Maya left Mako on 31 December 1941 to escort the Third Malaya Convoy, returning on 4 January 1942... The Maya left Mako on 6 January 1942 and arrived at Palau on 12th... The three units of Sentai 4 (Takao, Atago, Maya) remained at Palau until mid-February, conducting antisubmarine patrols in the vicinity. The Maya also escorted a convoy to Davao 21-28 January..."

Perhaps you can tell us your sources.

I also asked you a page back for the sources of the endurance values you stated for several cruisers. I doubt that these are correct.

By the way. The japanese Hobby Kit company Pit Road has a plastic model from the Atago from 1941 and this model has still the 4.7" guns as you can see here

Perhaps your sources are a bit spotty?
I definitely suggest you take a look at the book. They made extensive use of japanese sources. If the authors are not sure what is right they say so. If they could not find out something they state this fact also. I don't have any source that I would trust but this one.

Only to make sure this is in no way a personal attack against you! I honor your work you have done and will hopefully do in the future.

Marc

[Lemurs!]

Hi,

My sources for the most part are the records translated from Japanese sources and US intelligence interrogations that are held at the National Archives and at George Washington University.

As a secondary i referenced Norman Friedmans research paper on the Japanese navy.

Mike

[Don Bowen]

ORIGINAL: Lemurs!

Hi,

My sources for the most part are the records translated from Japanese sources and US intelligence interrogations that are held at the National Archives and at George Washington University.

As a secondary i referenced Norman Friedmans research paper on the Japanese navy.

Mike

Wow - those are great sources! Is there anyway I can get access to them (online maybe)?

Don

[Lemurs!]

Hi Don,

None of this is online sourcing. You can, however, go to the National Archives and to George Washington U. for this kind of info.

You used to be able to request this stuff from the archives, and more of it was available online and you could take a digital camera into the archives but our new paranoid government is restricting most of these activities while we speak.

Mike

[Don Bowen]

ORIGINAL: bstarr

Hey, here is one more site that I was getting a lot of info from on US AKs. I believe I've already listed the others.

http://www.usmm.org/ships.html

I also have an appendice which lists which Navy ships belong to which categorys, specifically the AKAs and APAs. If you don't have a list I can send it your way; it would certainly be easier to look down a numerical designation list like they have at HazeGrey. Let me know if you need it and I'll send it your way. I'll need to email it though, since it would be several scanned pages.

I'd appreciate the list - about ready to tackle allied cargo ships!

Finally dug out my book that gives an overview of the USMC designations. The book covers U.S. Army Transports and primarily gives data for ships used by the army. Here they are:

First Letter:
C = Cargo
P = Transport
T = Tanker
N = Coastal Vessel
S = Special?? Apparently includes LSTs and cable laying ships and also one class of Navy AKs.
R = Refrigerated Cargo ships

Number for C and R (not clear if for others as well):
1 = less than 400 feet (waterline when fully loaded, overall length was greater)
2 = 400-450 feet
3 = 450-500 feet
4 = 500-550 feet
5 = 550+

For N (Coastal), 3 = 250-300 feet but no other values are given. Many of these were in the U.S. Army's Southwest Pacific Area Fleet.

Second Letter, propulsion:
M = Diesel Motors
S = Steam Turbine

The Navy Alamosa Class AKs were C1-M-AV1. Other C1-M-AV1 were in merchant service, known as the "knot" series as many had names of knots ("Lanyard Knot", "Masthead Knot", "Bowline Knot", etc). Many of these became US Army Transports.

A "Special" cargo version of the C2 had upgraded engines and an additional half-size hold for special cargo - mail, secret stuff, admiral's whisky, etc. C2-S1-A1, good for 20 knots, used as US Army Transports.

There were several different designs within the 50-foot range for each numerical designation, especially the C2 series.

The Liberty Ships were EC2 type = Emergency C2. A greatly simplified design for ease of construction but fell within the general C2 category.

[Don Bowen]

Here's the USMC N3 Coastal Cargo vessel, based on a silhouette from U.S. Naval Vessels 1943. Very different from the "Baltic" rigged one in the above post. Primary use is in the U.S. Army’s South West Pacific Area Fleet and Alaska (and one Navy AK) so I think I'll use this one.

By the way, where's the flood of dissension over my un-scientific maneuver and durability ratings?

[Lemurs!]

Hi all,

This will probably scare some people, but... here goes.

On many figures given as fact i compare them to known figures for othercomparable items.

One example would be Myoko and Takao classes. They weighed pretty much the same. Marc, your figures for the Myoko at 14kts are pretty much the same as mine(small difference). The figures for Takao, though, have a huge difference.
My feeling is, lacking any research to the contrary, the Takao endurance would be very close to the Myoko. If not better as they were newer.

The numbers your book is providing us make the Takao class the shortest range, and least economical cruisers in the world.
I am willing to use intuition, logic, inference, whatever,
to say that i find those figures for the Takao unlikely.

I did the same in my mod for the published figures for the Yamashiro... it was listed as 16000nm or so with its fuel load which made it the most economical cruiser in the world. Not!
I lowered it to 11000 or so just as a guess. But fairly educated i hope.

Mike

[CobraAus]

here is the ec 2 liberty and a c2

Cobra Aus

[Don Bowen]

Matrix included depth charges in the original (12/41) armament of all of the "W" series minesweepers. However I can find no historical reference for their inclusion until the late-war ASW upgrades.

I am about to remove DC from all original "W" Series Minesweepers! This appears to be the historically correct thing to do but I am a little worried about the reduction in Japanese early-war ASW.

Comments appreciated.

Don

[Lemurs!]

Hi all,

Don, you the man!
That is my comment on removing the ASW from MSWs. Couldn't think of anything else.

So, after a ridiculus amount of research i have learned a bit about marine engines. And don't ever read Rogers & Mayhews 'Engineering Thermodynamics, Work and Heat Transfer'. My god is it boring.

Okay, the Takao could develop 130,000Shp. The Northampton could, for comparison, develop 107,000Shp.
The Takao carried 2571 tons of fuel oil. What kind of tons? I don't know. Don? Marc? What is naval fuel measured in? I am American so i made it 2000lbs per ton.
The Northampton carried 2100 tons of fuel oil.

A geared turnbine around 1930.... Okay, aprox 20% of Takaos power was needed to reach 14kts. The Northampton needed 20% to reach 15kts.

That would be 26000Shp for the Takao.
Diesel fuel burns at .136lbs per hp/hour.
However, geared turbines were about 88% effective generating power in 1930 for Japan and 91% for America. Have to work through the gears before you hit the shaft.
Plus, the drive for the propellor wastes about 3% of the power.

And Geared turbines were very inefficeint at speeds below 18-19kts. Triple expansion was actually much better up to about 16-17kts. You can see why countries switched engine types around the end of WW1.
Supposedly a 14-15kt geared turbine was about 60% of max efficiency.

Okay, so after all that I think the Takao uses 3.4612 tons of diesel per hour at 14kts, which would give 10399 mile (not kt) range. I am willing to bet that with the rebuilds, expansions etc to the Takao's they were NOT developing 14kts off of 20% power.
If you estimate 12kts/20% then the figure comes out to 8900 miles.

I really, really, feel that 5400 miles is so low as to be silly.
No turbine was that inefficient.

If you work the figures out for Northampton it comes out almost on the nose of 10000 mile range.

Mike

[Marc]

Hi Mike,

first you are absolutely correct not to trust every figure or statement that you read somewhere.
So I again took a look in the cruiser book and here are some passages that (in my opinion) describe quite well the figures I already stated and shows that the authors didn't just throw in an endurance value but commented them, as I think, very well.

Here the data for the Myoko and Takao classes:
Myoko-class as built: 8000nm/14 knots (designed), 7000 nm/14 knots (effective), 2470 tons oil
Myoko after first reconstruction(1936): only 4,000nm at 16 kts !!!!!
Myoko-class 1940: 2,214 t oil 8,500nm at 14 kts (planned), 7,463nm at 14 kts (effective) and 5,000nm at 18 kts.

Takao-class as built: 8000nm/14 knots (designed), 7000 nm/14 knots (effective), 2645 tons oil
Takao/Atago 1939: 8500nm/14 knots (planned), 5049 nm/18 knots (effective), 2318 tons oil


Myoko class as built:
"The maximum fuel capacity was 2470 tons of oil, and the designed endurance was 8000nm at 14 kts, which was considered the normal cruising speed in the early 1920s. The effective endurance was expected to decrease to some 7000nm as a result of the weight added before completion. Compared to the British Kent and the American Pensacola class, which carried about 3400 tons and 3000 tons of fuel oil, respectively, and had effective endurances of more than 10,000nm at 14 kts, the endurance of the Myoko class was more than 30% less. However, it should be remembered that when the Myoko class was designed, the Japanese assumed that the IJN would engage the U.S. Navy within about 1500nm of Japanese home waters..."

Takao class as built:
"The output of each of the cruising turbines proper was 3100 SHP at 5439 rpm, reduced to 1600 rpm by the cruising gear between the cruising and outer HP turbines. Over the whole turbine set, i.e. the cruising turbine plus the outer HP and LP turbines, the output reached 7,050 SHP at 170 rpm after reduction in the main gear, or 14,100 SHP for the port and starboard sets. This power yielded a cruising speedof 18 kts. A crusing speed of 14 kts could be obtained with 140 rpm and 3,750 SHP over the whole turbine set, 7,500 SHP for both shafts. In crusing conditions the main steam passed through the cruising turbines, whose exhaust steam was passed to the first stage of the common-use outer HP turbine, then over the outer LP turbine to the condenser; the inner HP and LP turbines were decoupled. In these conditions the turbine sets of the after engine rooms ran freely or could be disconnected at the main gear wheel. In other than cruising conditions, main steam was admitted simultaneously to both outer and inner HP turbines, the cruising turbines being bypassed and decoupled at the cruising gear...

The maximum fuel capacity was 2645 tons of oil, and the designed endurance was 8000nm at 14 kts. Because of the excess displacement, the actual maximum range was some 1000nm less. By the early Thirties, the Naval General Staff had concluded that a cruising speed of 18 kts was more acceptable than 14 kts. However, the power needed for 18 kts was about twice that for 14 kts, and the fuel consumption was correspondigly doubled. Thus, the maximum endurance at 18 kts was expected to be reduced to some 4000nm."

Myoko-class after second modernization:
"The boilers were retubed, and six of them were given steam preheaters. New burners were fitted, and the power of the blowers was increased. These measures reduced the fuel consumption...
The induction turbines fitted during the First Modernization were removed since they caused a lot of trouble. The revised cruising arrangement that was adopted allowed the steam from the cruising turbines, located in the forward turbine set, to be admitted directly to the aft HP turbines. Thus, cruising power was available on four shafts, facilitating transitions to higher speeds. Because of the increased displacement, a further drop in maximum speed was expected, the designed speed being 33.3 kts at 132000 SHP. The Myoko reached 33.88 kts with 132830 SHP at 14,984-tons displacement during trial run ... on 31 March 1941.
The maximum fuel capacity was reduced from 2472 tons to 2214 tons oil. Moreover, some 480 tons of fuel capacity were redistributed, mainly in the outer part of the original bulges and in the new bulges. Originally it had been expected that the boiler improvements would increase the radius of action to some 8500nm at 14 kts, notwithstanding the reduced fuel capacity and the increased displacement. However, more realistic predicitions brought that value down to 7900 nm at 14 kts, and the Myoko consumption trials yielded an effective radius of 7463 nm at 14 kts, or about 5000nm at 18 kts."

If I am not missing something the Maya and Chokai were the only two cruisers of the two classes that only used two shafts for cruising until their end. This was quite less effective than using all four shafts.

Since the book states for the Takao class only the endurance for 18 kts I would make a bet based on the known values from the Myoko class:
Myoko 5000nm - 18 kts , 7463nm - 14 kts
Takao 5049nm - 18 kts , 7500nm?? - 14 knots??


Marc


Finally here a scan from the book that shows some trial results of Myoko and Haguro after completion: