Two KGV's vs. Yamato

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Re: Two KGV's vs. Yamato

Postby tnemelckram » Tue May 11, 2010 9:28 pm

Hi Tommy!

I've never heard of the KGV's losing speed in the tropics but it could very well be true, so the best answer I can give off the top of my head is I see no reason why that would be unique to that class. Yamato is basically made of the same stuff and likewise subject to all of the things that reduce speed such as bottom fouling, machinery wear, etc.

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Re: Two KGV's vs. Yamato

Postby Bgile » Tue May 11, 2010 9:29 pm

Keep in mind that all other things being equal the Yamato's cruising range is significantly greater than that of the KGV class.

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Re: Two KGV's vs. Yamato

Postby tnemelckram » Tue May 11, 2010 9:34 pm

Hi Bgile!

Good point about cruising range. I agree that the Y is probably somewhat greater than KGV, but on the other hand her fuel consumption was so great and fuel scarce enough that the Japanese had trouble keeping her tank full. This is a significant potential problem for my plan because over enough time, Yamato could get away due to this.

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Re: Two KGV's vs. Yamato

Postby neil hilton » Wed May 12, 2010 2:24 pm

Dave Saxton wrote:
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.


Okay. So my theory of the Yamatos side opening and causing internal flooding due to a design flaw between the side belts isn't looking so good.
So how did those torps that did sink her cause so much flooding? Did they punch holes in the backs of the watertight compartments somehow? Or did the flooding of the watertight compartments themselves cause the ship to become unstable?
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Re: Two KGV's vs. Yamato

Postby Dave Saxton » Wed May 12, 2010 11:52 pm

Yes and no. It is unrealistic to expect that the inner citadel will always remain unbreached. Eventually damage beyond the practical parameters of the design will be received.

I’m more familiar with the details of the sinking of Musashi more than Yamato. Nonetheless, in the case of both it’s the massive scale and extent of the damage of ten plus torpedo hits (much the same can be said of Scharnhorst), plus the damage of bomb near misses. Musashi took a total of 19 or 20 torpedo hits. Moreover these hits were distributed asymmetrically rather than distributed evenly about the ships. 8 of the torpedo hits and 6 bomb near misses were forward of Musashi’s citadel in the large and long but poorly protected bow section. The Yamato class had a protected length only 51% of the waterline length of the ship. Musashi’s bow was heavily flooded by one or two early hits forward that cost the ship a great deal of speed and handling and a severe trim problem though out its final battle. Latter hits hit areas already damaged by earlier hits. The port side received 13 of the torpedo hits. This caused flooding of the outboard compartments on that side to be much more extensive and to proceed far more quickly than on the starboard side.

Asymmetrical lateral flooding quicker than counter flooding could cope with; is believed to be the eventual cause of the loss of stability in Yamato.

In Musashi’s case it was asymmetrical longitudinal flooding of the forward areas of the ship that was the main concern. In the case of Musashi most of the citadel had remained mostly intact but eventually as more torpedo hits were received in already damaged areas, and as the riveted construction began to loose integrity under the relentless pounding, flooding began to progress into the vital compartments, mainly on the port side, compounding the problem of asymmetrical flooding. Eventually as vital machinery compartments began to fall to the progressive flooding the mechanical, propulsive, and electrical power, also began to fail. Once the pumps failed, Musashi was doomed.
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Re: Two KGV's vs. Yamato

Postby dunmunro » Thu May 13, 2010 1:05 am

Bgile wrote:Keep in mind that all other things being equal the Yamato's cruising range is significantly greater than that of the KGV class.


Not really. The KGV class had their FO capacity increased to ~4000 tons, and at that figure there was only a few hundred miles difference between the two classes.

On trials Yamato achieved .8162 lb/SHP fuel consumption*, or about 54.65 tons/hr at 27 knots (150000 SHP) for a range of 3112nm with 6300 tons of FO. Howe used 36 tons/hr of FO at 27 knots for a range of 3000nm at 27 knots with 4000 tons FO. Nominal cruising range for Yamato at 16 knots = 7300nm versus about 6800nm for Howe, with 4000 tons FO.

* Anatomy of the Ship, Yamato gives .8162lb/shp in a table but then states that Yamato consumed .9lb/shp while at full power, for 61.56/tons hr. This would give a range of ~2800nm at 27 knots.

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Re: Two KGV's vs. Yamato

Postby alecsandros » Thu May 13, 2010 10:25 am

I don't understand the importance of range in this hypothetical engagement.

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Re: Two KGV's vs. Yamato

Postby lwd » Thu May 13, 2010 2:16 pm

alecsandros wrote:I don't understand the importance of range in this hypothetical engagement.

Some of the tactics being expoused would take a considerable amount of maneuvering. I don't see it as being enough to bring this factor into play but some might.

On a different note apparently the fireing arcs of Yamato's main battery were all 300 degrees. That is there was a 30 degree arc off the stern that the forward battery couldn't cover.
From: http://www.j-aircraft.org/smf/index.php?topic=9331.0

As for turning I get 28 knots as ~933 yards/minute. Call it 900 yards/minute if one has a turning circle of 900 yards (Yamato's is somewhat less than 700 yards) that's 360 degrees per minute or 6 degrees/sec so under 5 seconds to allow the full main battery to engage a target directly astern.

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Re: Two KGV's vs. Yamato

Postby neil hilton » Thu May 13, 2010 2:26 pm

What about the considertion of tilting as she turns, thus throwing off her gunnery until she settles back down, that could take minutes after a full rudder turn.
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Re: Two KGV's vs. Yamato

Postby lwd » Thu May 13, 2010 2:43 pm

I don't think it's going to take minutes and she hardly needs to use full rudder. Yamato may lack the stable verticles of the Iowa but look at how well she shot vs the Nowaki and she was persuing at full speed with turns to allow her to use her full main battery. In this case if the British ships are at 45 degrees on either side of Yamato's stern they are already engageable by the full main battery. It only becmes necessary to turn if they are less than 30 degrees off the stern. If they are 20 degrees off the stern then full rudder brings them into the arcs in 2 seconds. Not sure if it's linear but this would imply hat 1/4 rudder would take all of 8 seconds to do so. If she makes a bit of smoke before the turn it's likely that the British will not know she has turned until she fires or at most a few seconds before.

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Re: Two KGV's vs. Yamato

Postby Bgile » Thu May 13, 2010 3:05 pm

lwd wrote:I don't think it's going to take minutes and she hardly needs to use full rudder. Yamato may lack the stable verticles of the Iowa but look at how well she shot vs the Nowaki and she was persuing at full speed with turns to allow her to use her full main battery. In this case if the British ships are at 45 degrees on either side of Yamato's stern they are already engageable by the full main battery. It only becmes necessary to turn if they are less than 30 degrees off the stern. If they are 20 degrees off the stern then full rudder brings them into the arcs in 2 seconds. Not sure if it's linear but this would imply hat 1/4 rudder would take all of 8 seconds to do so. If she makes a bit of smoke before the turn it's likely that the British will not know she has turned until she fires or at most a few seconds before.


I think it takes a long time to move the rudder over ... many seconds for full rudder in a battleship. 15 or more springs to mind, but I could be mistaken. Also, the ship doesn't start turning the instant the rudder moves. I'm fairly sure it's not quite as fast as you are implying, but still fast enough to be doable. If they were shooting they probably wouldn't use large amounts of rudder anyway.

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Re: Two KGV's vs. Yamato

Postby neil hilton » Thu May 13, 2010 3:08 pm

lwd wrote:I don't think it's going to take minutes and she hardly needs to use full rudder. Yamato may lack the stable verticles of the Iowa but look at how well she shot vs the Nowaki and she was persuing at full speed with turns to allow her to use her full main battery. In this case if the British ships are at 45 degrees on either side of Yamato's stern they are already engageable by the full main battery. It only becmes necessary to turn if they are less than 30 degrees off the stern. If they are 20 degrees off the stern then full rudder brings them into the arcs in 2 seconds. Not sure if it's linear but this would imply hat 1/4 rudder would take all of 8 seconds to do so. If she makes a bit of smoke before the turn it's likely that the British will not know she has turned until she fires or at most a few seconds before.


Full speed turns with full rudder really do tilt a ship over quite a lot and it does take a while to settle down, full speed turns or full rudder turns individually also cause significant tilting, even on modern ships with stabilizers.
Not sure how much automatic gun stabilization can cope with before failing. Depends on the design.
If Yamato does any radicle manoeuvring it would take awhile to settle, minutes might be a bit of an overstatement but not by much I think. Shes a very big lump of iron with a lot of momentum thats trying to quickly change vector in a fluid.
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Re: Two KGV's vs. Yamato

Postby lwd » Thu May 13, 2010 7:20 pm

But as long as the motion is slow the fire control system should be able to compensate and as the numbers demostrate there is no particular reason to peform radical maneuvers when even a 1/4 max turning rate you are only looking at a few seconds to turn far enough to bring the guns to bear.

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Re: Two KGV's vs. Yamato

Postby alecsandros » Fri May 14, 2010 11:15 am

neil hilton wrote:
Full speed turns with full rudder really do tilt a ship over quite a lot and it does take a while to settle down, full speed turns or full rudder turns individually also cause significant tilting, even on modern ships with stabilizers.
Not sure how much automatic gun stabilization can cope with before failing. Depends on the design.


This is a function of the integrated fire control system. On US and German heavy ships, the "stable element" mantained the guns and turrets at the level necessary for the firing solution to work. On Bismarck, for instance, the system was capable of compensating for a rate of roll of up to 15*/sec. Firing trials conducted aboard Prinz Eugen in 1943 proved that even performing 360* turns, the firing solution could be mantained.

Yamato did not posses such a system. It's turrets and guns were trained/elevated based on a "follow-the-pointer" (manual) method. THe question would be how skilled would the Japanese sailors be. If the answer is "highly skilled", than the fire control solutoin could have been mantained just as good as in a fully-automated system. If the answer is "moderately" or "low skilled", the problem would be more complex for them, and consequently the solutions would not be that good during hard turns.

However, for the sake of the discussion, I guess we could presume all 3 crews to be very skilled.

Cheers,
Alex

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Re: Two KGV's vs. Yamato

Postby lwd » Fri May 14, 2010 1:57 pm

Well if Yamato is really going to turn on the British ships she can do so in a few 10's of seconds and allow a few more for things to stabalize without it being too significant. Indeed if she's been making smoke it may require even more time for her to clear the cloud. The presence or absence of a stable verticle does mean that even if we assume equal skill levels what that skill level is may have some impact.


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