Two KGV's vs. Yamato

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neil hilton
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Re: Two KGV's vs. Yamato

Postby neil hilton » Tue May 11, 2010 3:34 pm

Interesting.
Was this join between upper and lower belts above or below the waterline? (I assume below).
Was the juncture above the watertight compartments? ie if the joint between the upper and lower belts failed would flooding go into the watertight compartments or into the hull?
If the structural member between the plates was attached to an internal deck would a failure distort the deck sufficient to cause flooding?
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Re: Two KGV's vs. Yamato

Postby Dave Saxton » Tue May 11, 2010 3:36 pm

I see that he had one source suggesting MNC was based on German Wh, while another source suggested it was based on British NCA.
If I understand his writing correctly, the design specifications of the plates included 0.15% Ni, but supply shortages led to it's replacement by Cu.


0.15% Ni or Cu isn't very much. The British and American homogenous armours had around 4% Ni, and this is the approx amounts I recall of the Japanese MNC specific to the Yamato class. I recall being struck by how close it was to British NCA.

In chromium/molybdenum alloy metalurgy (such the German homogenous armours) the amount of Ni is often deliberately depressed, as its the combination of chromium with molybdenum working together that are the primary alloying agents. Too much Ni in Cr/Mo alloys can lead to excessive hardening. If the metalurgy is Cr/Mo then the amount of Ni is not normaly important to the potential quality of the armour.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Two KGV's vs. Yamato

Postby Dave Saxton » Tue May 11, 2010 3:43 pm

neil hilton wrote:Interesting.
Was this join between upper and lower belts above or below the waterline? (I assume below).
Was the juncture above the watertight compartments? ie if the joint between the upper and lower belts failed would flooding go into the watertight compartments or into the hull?
If the structural member between the plates was attached to an internal deck would a failure distort the deck sufficient to cause flooding?


The joint was below the waterline.
A failure of the joint would only cause flooding into the watertight compartments behind the lower belt.
The structural member was not attached to any deck structure but to the first set of bulkheads behind the lower belt.
Displacement or distortion of the outboard structures would not effect the inner holding bulkheads.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Two KGV's vs. Yamato

Postby lwd » Tue May 11, 2010 3:45 pm

tnemelckram wrote:... Maybe you underestimate the amount of course change needed to bring the fore guns to bear.

That's possible. Do you have a number for the arc of fire for Yamato's main guns? If the two British ships are off her stern quarters that puts them at roughly 45 degrees off each stern. Looks pretty close to the arc of fire to me and the Yamato's were apparently pretty handy vessels for battleships. I don't see the Yamato continueing to try and run if she is being persued by two faster battleships in any case.
...
The obscuring of Yamato is a damn good point. It could come from as many as 12 simultaneous splashes,

At Denmarck straits the British ships had assigned time slots to fire so as not to confound their splashes. I'd assume something similar would be done here.
"If you don't get too close 2 knots gives you a decent chance of disengaging and makes it hard for the other guy to do so."

This is the key to my plan. It appears you think that it is on solid ground at least to the extent that the British could probably control where and when the shooting takes place.

The problem here is if they get close enough to engage they may be too close. Especially if they take a hit or two. Many different types of damage can slow down a ship.
... The parts of the British ships most exposed to damage are the forward guns that are the spear point and the bridge and other CCC structures. The propulsion nmad steering in the rear are least exposed. So if the forward hull is still intact, there is still a good chance of being able to chicken out and run away if the battle damage makes the kitchen too hot.

Even near misses can cause problems that affect speed as can damage to the stacks not to mention hull hits at or near the waterline.

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Re: Two KGV's vs. Yamato

Postby tnemelckram » Tue May 11, 2010 6:02 pm

Hi LWD!

Good stuff.

Do you have a number for the arc of fire for Yamato's main guns? If the two British ships are off her stern quarters that puts them at roughly 45 degrees off each stern.


You are right, 45 degrees is exactly what i have in mind! I'll have to do some research to find out about the Y's fore battery firing arcs. If it turns out 45 degrees exposes me too much, I might have to make the angle more acute to whatever it is to avoid exposure, but of course I can't increase it too much because there's a point where the angle becomes too great and makes my plan unfeasible.

I don't see the Yamato continuing to try and run if she is being pursued by two faster battleships in any case.


In my above post I don't say she is running,. but will be constrained by her mission and tactical circumstances to continue her general course by default. The Japanese Captain could write in his war diary: "Undeterred by the presence of the two British Battleships, we continued majestically and unperturbed on our assigned task, with the trembling British following at a respectful distance, afraid to come alongside and fight like men, even though they could try if they dared".

At Denmark straits the British ships had assigned time slots to fire so as not to confound their splashes. I'd assume something similar would be done here.


At DS the two British were in close formation and basically shooting from the same place. One of the ideas of my plan is that the Britishh would be shooting from two distinct places separated by 90 degrees.
It would probably be better for them to fire independently instead of in time-coordinated salvos because Yamato could figure out the timing and to aid her "salvo chasing". If practical, I'd try to count on distinguishing the landing shots by whatever distinct appearance they would have because they originated from two points 90 degrees apart. I sense there would be a discernible difference.

EDIT TO ADD: What you say about battle damage is possibly true and a definite concern. But perhaps the best way to use that in criticizing my plan is to bundle it with my perhaps giving the British more knowledge about Yamato's capabilities that they may have had historically. For example, the 18 inch guns were strongly suspected later on in the war but not confirmed until after the war. If Yamato shot at them and her first sasalvos missed as they most likely would, the British probably wouldn't be able to tell from the splashes alone that they were 18 not 16. It would probably take actually getting plastered with one to figure it out, in which case they might have already sustained the damage you mention and found out the truth too late..
Last edited by tnemelckram on Tue May 11, 2010 6:24 pm, edited 1 time in total.

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Re: Two KGV's vs. Yamato

Postby lwd » Tue May 11, 2010 6:16 pm

tnemelckram wrote:
Do you have a number for the arc of fire for Yamato's main guns? If the two British ships are off her stern quarters that puts them at roughly 45 degrees off each stern.

You are right, 45 degrees is exactly what i have in mind! I'll have to do some research to find out about the Y's fore battery firing arcs.

I looked on line but couldn't find much. One model description I read had a had the arc of the forward turrets coming to within 50 degrees of the stern I believe but not sure how accurate the model is. There's a coupe more places I can look will report if I find anything. I seem to recall that in the action vs Nowaki Iowa was turning just before she fired so she could fire full salvoes where New Jersey was only using her forward guns.
... In my above post I don't say she is running,. but will be constrained by her mission and tactical circumstances to continue her general course by default. The Japanese Captain could write in his war diary: "Undeterred by the presence of the two British Battleships, we continued majestically and unperturbed on our assigned task, with the trembling British following at a respectful distance, afraid to come alongside and fight like men, even though they could try if they dared".

My impression of the Japanese is they would have jumped at the chance to engage an opposing battleship. Even outnumbered 2:1 I suspect Yamato would have done so.
At Denmark straits the British ships had assigned time slots to fire so as not to confound their splashes. I'd assume something similar would be done here.

At DS the two British were in close formation and basically shooting from the same place. One of the ideas of my plan is that the Britishh would be shooting from two distinct places separated by 90 degrees.
It would probably be better for them to fire independently instead of in time-coordinated salvos because Yamato could figure out the timing and to aid her "salvo chasing". If practical, I'd try to count on distinguishing the landing shots by whatever distinct appearance they would have because they originated from two points 90 degrees apart. I sense there would be a discernible difference.

I suspect the seperation would make this even more useful. The patterns are normally more or less normal in both axis with a somewhat lesser spread in azimuth. Especially if they came close to overlapping very difficult to distinguish unless conditions are such that the colors show up well. Timing it so that they were firing say 30 seconds apart might actually complicate the salvo chasing as Yamato would have to decide which salvo to chase.

Any idea what the arc of fire of the KGV's was? When can they get their rear turrets into action in this sort of engagement?

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Re: Two KGV's vs. Yamato

Postby tnemelckram » Tue May 11, 2010 6:33 pm

Hi LWD!

My impression of the Japanese is they would have jumped at the chance to engage an opposing battleship.


I agree that is what they would want to do. But what they can do in light of their overall in transit mission and the small speed advantage that might allow the British to dictate whether or not there will be action are two different things.

Timing it so that they were firing say 30 seconds apart might actually complicate the salvo chasing as Yamato would have to decide which salvo to chase.


Now we got 'er on the run! But seriously, I'll see if I can find anything more about the fore firing arcs. Thanks for your info - 50 degrees seems reasonable.

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Re: Two KGV's vs. Yamato

Postby lwd » Tue May 11, 2010 7:50 pm

I didn't book mark it but one site mentioned that the Iowa had a turning circle of 800m(yards?) and the Yamato 640. So it wouldn't take her long to turn a few degrees.

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Re: Two KGV's vs. Yamato

Postby Bgile » Tue May 11, 2010 8:34 pm

tnemelckram wrote:I agree that is what they would want to do. But what they can do in light of their overall in transit mission and the small speed advantage that might allow the British to dictate whether or not there will be action are two different things.


I suppose you can dream up any number of handicaps to make it possible for the British to win. How about Yamato is anchored in a lagoon with maintenance being performed on her main battery director such that it can't be used for an hour? I bet I could come up with some others, too.

A lone destroyer can be more powerful than Yamato if you set up the conditions right. How about night time with low visibility? You've already decided that for some strange reason Yamato has no escorts. A lone destroyer comes in close and hits her with six torpedoes out of ten and sinks her. It could happen.

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Re: Two KGV's vs. Yamato

Postby Bgile » Tue May 11, 2010 8:38 pm

lwd wrote:I didn't book mark it but one site mentioned that the Iowa had a turning circle of 800m(yards?) and the Yamato 640. So it wouldn't take her long to turn a few degrees.


That's pretty incredible. An Iowa could out turn a Fletcher class destroyer, but an Iowa has two rudders, each directly behind a screw. I don't know what the actual turning circles were though, so you may be right. Initial speed is an important aspect of this, of course.

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Re: Two KGV's vs. Yamato

Postby tnemelckram » Tue May 11, 2010 8:45 pm

Hi Bgile!

I suppose you can dream up any number of handicaps to make it possible for the British to win.


I really don't think I have dreamed up any handicaps for the British to win. My scenario has all ships performing wartime missions with full operational capacity. It is premised on the Yamato being somewhat constrained by her mission, which is indeed a premise but not an operational handicap, and a 2 knot British speed advantage, which is real and documented.

As to escorts, the OP didn't factor in any escorts, so I ignore them as well although I agree that both sides would certainly have them. Perhaps the best way to rationalize that is the escorts cancel each other out in terms of ability to affect the course of action leaving you with the pure "BB vs 2 BBs" scenario in the OP. .

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Re: Two KGV's vs. Yamato

Postby Bgile » Tue May 11, 2010 9:05 pm

Well, you seem to have put Yamato in an artificial position where her orders prevent her from firing back. That sounds pretty decisive to me.

Note also that if both sides have destroyers, Yamato would gain the most advantage because her escorts could screen her with smoke.

They could also attack with torpedoes and force the British to make major course changes and lose contact with Yamato. Or pretend to attack with the same result.

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Re: Two KGV's vs. Yamato

Postby tnemelckram » Tue May 11, 2010 9:08 pm

Hih LWD!

I agree about the 640 Yamato tactical radius. It's a problem for my plan because she is really quick on the turn to bring the fore guns to bear, whatever the effective angle is. I'm going to have to rely on the sharp eyes and other skills of my British crews to timely spot it, which has been bred into them by 300 years of tradition.

I looked at the Naval Technical Mission To Japan Reports to find what the effective fore turret training angles was but haven't been able to find the answer. I though that would be about the closest hand information available. Although that answer might not be there, they did make a detailed report about Japanese efforts to educate their crews about and prevent the age old problem of venereal disease in the fleet. It appears that men of all nations have the same priorities and present their officers with the same problems. It makes you wonder why they would have the time, energy or inclination for war in the first place.

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Re: Two KGV's vs. Yamato

Postby tnemelckram » Tue May 11, 2010 9:14 pm

Hi Bgile!

Well, you seem to have put Yamato in an artificial position where her orders prevent her from firing back.


No, not at all. My posts make it clear that she can try to fire back all she wants and that she may or may not be successful. It's just that if the British speed allows them to evade and dictate when effective shooting will occur, the Yamato can't force action even by turning to shoot, and she is not going to just stop and sit there and double dog dare the British to come into range. Just sitting there indefinitely is ridiculous, so she would at that point instead resume her in transit mission, with the British following and looking for another opening . . . .

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Re: Two KGV's vs. Yamato

Postby tommy303 » Tue May 11, 2010 9:20 pm

Just out of interest, did not the KGV's lose a bit of speed when operating in the tropics? If so, the speed advantage might have been less than the two knots assumed.

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