WW II Historical Thread, Discussion, Pics, Videos

[Jeff Head]

Jeff, you make it sound like the 7th fleet support force of 6 battleships, 4 heavy cruisers, 4 cruisers, 28 destroyers and 39 PT boats had a fair fight...

Who said anything whatsoever about a fair fight? Not I...not in the least.

Here, let me relieve you of that impression.

The American Admiral absolutely did not want a fair fight and he laid three layers of traps (PT boats, and then two layers of destroyers) along the Strait to progressively attrit the Japanese force as they approached his final bear trap...which was his cruiser and battleship battle line, and then he shut it tight on what was left.

The fact that 6 american BB was firing on Yamashiro and Mogami as only these two got to the american lines; and that the high level of hits started to land only after the hull was ablaze (which really mean that optical gun laying was used) and that both ship were able to slip away from the american line.

Actually, the very first salvo from the West Virginia at 22,800 yards hit the Yamashiro.

And though the Yamashiro and Mogami "survived" the run along the line, they were finished. US Admiral Olendorf called a cease fire when one of his own vessels was hit by friendly fire. Otherwise he could have continued to pound the Japanese vessels. But he knew he had them, and did not want to risk more American deaths in such a lopsided victory. So, the Japanese turned away...and the Yamashira, which was burning pretty much stem to stern, sank ten minutes later after taking two more torpedo hits from US torpedoes.

The Mogami although burning badly and severely damaged, fought on doggedly and was not sunk until after daylight, when Avenger aircraft, ironically from the Taffy aircraft carriers that were being pummeled at the time by the central force, finally put her down.

It is also to be noted that it was only the West Virginia's radar that got the firing solution, Older BB like the Maryland, Mississippi, Tennessee, California and Pennsylvania, did not get a radar firing solution and had to rely on optical sighting. - All of whom are younger than the Yamshiro except maybe for the Penn.

Actually, the California and Tennessee had been upgraded to the Mark 8 fire control and also obtained firing solutions of their own.

US fire control radar is definitely better

Which was actually my only point.

 

[Jura The idiot]

I think we could also ask ourselves what might have happened had Britain and France stood up to Hitler in the early days of Hitlers rise. A Second World War might have been avoided and would Japan have started a pacific conflict if the European powers had not been defeated.

A frequent opinion (not mine! is that Japan was put in untenable position by the embargo of October 16, 1940. It seems this would have happened even if there had been no war in Europe at that time.

Jeff, chuck731, Rutim, Lezt, a fascinating read for this early morning here!

 

[Jura The idiot]

Two points related to duels of battleships you guys have discussed:

1. Quote,

The rangekeeper's target position prediction characteristics could be used to defeat the rangekeeper. For example, many captains under long range gun attack would make violent maneuvers to "chase salvos." A ship that is chasing salvos is maneuvering to the position of the last salvo splashes. Because the rangekeepers are constantly predicting new positions for the target, it is unlikely that subsequent salvos will strike the position of the previous salvo.[12] The direction of the turn is unimportant, as long a it is not predicted by the enemy system. Since the aim of the next salvo depends on observation of the position and speed at the time the previous salvo hits, that is the optimal time to change direction. Practical rangekeepers had to assume that targets were moving in a straight-line path at a constant speed, to keep complexity to acceptable limits.

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The "nominal rate of fire" was 30 seconds for both Iowas and Yamatos (details:

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); plenty of time for a turn, I guess ... But I'm not saying any of these ships would have tried to run away! What I think is that the maneuvering, if it had been performed, would have favored the US Navy battleships, because they were able at the same time to aim (and shoot) and make turns, quote,

In 1945 test, an American battleship (the North Carolina) was able to maintain a constant solution even when performing back to back high-speed 450-degree turns, followed by back-to-back 100-degree turns.7

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, while for the Japanese it would have been advantageous to close the distance so the striking velocity had been as high as possible for the 1460 kg 18" shells.

2. An interesting webpage:

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also includes a Japanese account of what's happened on the night of November 14-15, 1942 "fair and balanced" heheh

 

[Lezt]

Two points related to duels of battleships you guys have discussed:

1. Quote,

The rangekeeper's target position prediction characteristics could be used to defeat the rangekeeper. For example, many captains under long range gun attack would make violent maneuvers to "chase salvos." A ship that is chasing salvos is maneuvering to the position of the last salvo splashes. Because the rangekeepers are constantly predicting new positions for the target, it is unlikely that subsequent salvos will strike the position of the previous salvo.[12] The direction of the turn is unimportant, as long a it is not predicted by the enemy system. Since the aim of the next salvo depends on observation of the position and speed at the time the previous salvo hits, that is the optimal time to change direction. Practical rangekeepers had to assume that targets were moving in a straight-line path at a constant speed, to keep complexity to acceptable limits.

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The "nominal rate of fire" was 30 seconds for both Iowas and Yamatos (details:

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); plenty of time for a turn, I guess ... But I'm not saying any of these ships would have tried to run away! What I think is that the maneuvering, if it had been performed, would have favored the US Navy battleships, because they were able at the same time to aim (and shoot) and make turns, quote,

In 1945 test, an American battleship (the North Carolina) was able to maintain a constant solution even when performing back to back high-speed 450-degree turns, followed by back-to-back 100-degree turns.7

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, while for the Japanese it would have been advantageous to close the distance so the striking velocity had been as high as possible for the 1460 kg 18" shells.

2. An interesting webpage:

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also includes a Japanese account of what's happened on the night of November 14-15, 1942 "fair and balanced" heheh

One thing to remember is that having a firing solution doesn't mean that the solution actually works. simple temperature change of the barrel, minute differences in shell weight and propellant charges or vibration from other machinery would easily create a dispersion of hundreds of meters or lengths of ships at extreme range - especially as it takes a minute for the shell to arrive at extreme range. Radar definitely makes it easier to determine vector and keep range, but these early systems are not that fast and work best if host ship is moving at a constant speed and heading; and likewise the target ship is relatively constant. Hence battle lines are still necessary to fire accurately while crazy maneuvering will mess up any firing solution.

That being said, it is true that Japanese ships are better off closing the gap quickly, Espically in this case as the Yamashiro had very thin deck armor to resist plunging fire and she needed to shorten the range so her optical range finder can work - i.e. she like the bismark was built for a short range slug fight. But the times have moved on to plunging fire way of waging war; especially in the pacific.

Fire control is honestly such a complicated topic that I find it hard to just comment that a particular system is best. The German Mittlungsapparat/Gangmittler optical/radar range finder with with the synthetical fire control (Pollen's Argo derivative system) performed remarkably well Bismark vis Hood; just as the the Ford (which is Pollen's Argo inspired) synthetical fire control performed well on US BBs; while the Japanese Aichi (also developed from the Argo) preformed well in the Guadalcanal (in terms of accurate gun fire); while the British stuck with their analytical fire control clocks; which were slower to straddle.

My main point is that radar is really only a means of range finding, having found the range does not automatically mean that a firing solution can be generated. It doesn't mean that the Japanese system is inaccurate or ineffective; it is only that the US computer is a closed loop automated system that doesn't get affected by human errors as much. Radar is also not as dominating as history books make it out to be; ww2 radars being very susceptible to ground clutter and environmental aberrations - which the japanese took full advantage of (although to no avail against the numerical superiority).

It is really like, what the rifle did to the knight/Samurai; or the assault rifle to the riflemen; the US fire control is simpler to use and easier to train crews for new ships. The Japanese system needs years of practice and fresh crew to preform; both of which were in short supply in late war.

Here is an interesting read:

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[Rutim]

In fact, I believe that the only time a Yamato battleship ever fired on another surface ship in combat was also during the great BAttle of Leyte Gulf during the Battle off Samar, when the Imperial Japanese Navy's Central Force under Admiral Kurita including the battleship Yamato herself, engaged the Escort carriers of Taffy 3 under US Admiral Clifton Sprague.

This is an amazing picture from that battle. In the foreground is the US escort carrier, Gambier Bay, CVE-73, hit and being strattled by direct gunfire. On the horizon, just to the right of the carrier, is a surface ship, some think may be either the Yamato herself, or a heavy cruiser, actually within visual range. An amazing picture. The Gamier Bay was sunk in this action.

USS Gambier Bay, CVE-73, hit and bracketed by gunfire, October 25, 1944
​

The vessels which strifed Gambier Bay with gunfire were battleship Kongo and heavy cruiser Chikuma. Kongo and heavy cruisers squadron (beside Chikuma there was Tone, Chokai and Haguro) took a turn to the prt early in the battle leaving the rest of the fleet (with Yamato, Nagato, Kirishima, destroyers and rest of the cruisers) and concentrated fire on the last vessel in Taffy's 3 formation. The fire wasn't continous as there were squalls going throught the entire battle here and there making the gunfire ineffectove as they couldn't confirm where it landed. After some time and few shells penetrating Gambier Bay structures without detonations a shell from Kongo hit it underwater and flooded part of machinery spaces. This made Gambier Bay dropping to 11 knots as the bombardment continued leaving her burning and dead in the water to sink later. The photo most likely depicts Chikuma which was sunk later in action that day after being hit by one of those 'phantom' torpedoes. The thing that none torpedo hit while Yamato was under heaviest fire from enemy aircraft in Leyte action is said to happen due to master skills of the captain, Nobue Morishita who was said to be master of evasive movements on such a big vessel and earned great respect in the Navy for that.

And yes - Yamato most likely hit USS White Planes with her main gun shell which struck on the port side of her and exploded under the keel making her withdraw in effect after the battle ended and recorded on tape. The distance would be between 30,5-31,5 km.

In the last Battlesip vs. Battleship gun duel in history, during the great Battle of Leyte Gulf, in the Battle at Suriago Strait in October 1944, the Mark 8 Fire Control on the US Navy West Virginia, California and Tennessee battleships, and the Mark 3 fire control on the Maryland, performed admirably, and the fire control, such as it was, that was fitted to the Imperial Japanese Navy vessels under Admiral Nishimura, the battleships Fuso and Yamashiro and the heavy cruiser Mogami perfomred and four destroyers pitifully. Actually, the Yamashiro was the only one that made it to the actual gunfight as the Fuso was disable and ultimately sunk by torpedoes before reaching the main battle, but en route her radar performed very badly just the same.

Few years ago there was an interesting statement from a man who served aboard Yamato, Shunnosuke Fukai who was chief of 155mm artilery. He was given a dagger from Admiral Ozawa who commanded the other part of the fleet and succeed in his plan. That dagger, Mr Fukai said, he had to use in case of Kurita neglecting to pick up a fight with US Navy and running away to stab him. He said that Ozawa was afraid that Kurita will once again run away from the show down like he did in Midway battle. You can only guess how big were the frictions between those who wanted to fight to the end and those who already knew the war is lost. He talked about a mysterious depeche that arrived on Yamato's bridge after which Yamato took an U-turn from the battlefield and a big turmoil on the brodge discussing the decission. And what force does it have when told by a man who new all those people and observed the bombardment of Taffy 3 with glass of rangefinder on top of Yamato's conning tower! He also said they were sure they hit one of the carriers with second salvo after first landed too far. He also confirms that Yamato fired on radar bearings in squall but they were unable to confirm the hits.

US Navy got perfect conditions even the place to pick up a fight was decided in a way to use Japanese Navy sortcomings to the maximum (like operating close to the shores knowing that Japanese radars have problems in such environment). Classic crossing the T would be impossible on open sea as well. US forces were closely watching over the Japanese fleet from the time the first sight by aircraft as they closed to Surigao. I'm afraid that on bridge of every Japanese vessel everyone knew that they won't make it out of the battle and it was suicidal mission from that point.

 

[chuck731]

According to Norman friedmann's book, there were several serious weaknesses with Japanese surface fire control systems in comparison with those of other naval powers.

1. British, American, and german fire control computers receive most of their inputs through direct electrical and mechanical linkages with range finder, firing director, and radar. This assures prompt and mostly error free transmission of input data from observation instruments into the fire control computer. Japanese fire control computers relied mostly on manual transcription of data from dials and scales on the observation instrument to control dials on the computer. The reading from observation instrument would appear on a dial, and operator would read the dial manually and call out the reading through voice tubes or internal telephones to another operator near the fire control computer deep inside the ship, and there the operator would rotate a hand wheel on the computer to bring a second dial on the computer to match the readings he just heard. This builds in both a time lag and room for operator error in the transmission of data from observation instruments to the fire control computer.

2. Fire control system needs an a horizontal reference to detect inclination of the ship in order to effectively control gun fire in a pitching and rolling, and possibly listing, ship. American and German systems uses gyroscopes to automatically provide a continuously updated artificial horizontal reference to the fire control computer, again assuring a prompt and mostly accurate artificial horizon. Japanese system relies on human operators looking through telescopes at the horizon, and constantly turning hand wheels to keep cross hairs on the horizon to provide horizontal reference to the fire control computer. So in case of very poor visibility, due to smoke, weather, or heavy sea, Japanese fire control computers don't work because the operators can not see well enough to keep crosshairs on the horizon. Blind fire in rough sea and very poor visibility, like that which the British used to destroy the Scharnhorst in battle of north cape, is impossible for Japanese ships even if Japanese radar was up to par because without visibility, Japanese fire control systems can't compensate for pitch and roll of their own ships.

3. The standard system of transmission of fire control instructions from the fire control computer to the individual gun turrets aboard Japanese ships were poorly designed. On American and German ships, the gun training and elevation were continuously autoindexing. That means the bearing and elevation of each turret can be instantly shifted from control by one director to control by another. Little time would be lost if one director is knocked out and a backup must take over. On Japanese systems the guns were not autoindexing. If control needs to be assigned to a director, or shifted from one director to another, the all guns and the associated director must return to zero degree train and neutral elevation in order to synchronize the position of the guns to the position of director. Any target the director had been tracking and building firing solution for would be lost. Only when all turrets and all assoicated director have come to 0 degrees train and elevation can the director start to reacquire the target and re-build the firing solution. It is estimated on Japanese ships, if the director is knocked out, there would be a 1-2 minute dead space as all guns have to return to zero degree train and elevation to,synchronize with the backup director, before the backup director can begin tracking the target again. Since targeting solution improves with the amount time the director had been tracking the same target, when a Japanese warship's gun battery come back online after a director shift, the solution would be poorer than before the shift, and would have to build back up again. There is no such draw back with American and German system. Both primary and backup directors can continuous track targets and improve their individual solutions, and guns can be freely shifted from control by one to count roll by another with little loss of time and no loss of accuracy.

Yamato, her sister Musashi, and Hiei - the last old battleship to be modernized prior to WWII, were the only ships to receive the very latest surface fire control systems Japan ever devised. This new system corrected much of problem 1 by adapting electrical signal transmission from the directors and range finders to the firing computer, and from firing computer to the guns. But didn't do anything about problems 2. The Japanese never overcame the inability of their industry to produce adaquate gyroscopes for automated artificial horizon for fire control. A system tested in 1942 proved inadaquate for actual use. An single example of an improved system was installed experimentally in one aircraft carrier at the end of the war, but never saw real service. It is not clear to me if the new system did anything about problem 3.

 

[Lezt]

According to Norman friedmann's book, there were several serious weaknesses with Japanese surface fire control systems in comparison with those of other naval powers.

1. British, American, and german fire control computers receive most of their inputs through direct electrical and mechanical linkages with range finder, firing director, and radar. This assures prompt and mostly error free transmission of input data from observation instruments into the fire control computer. Japanese fire control computers relied mostly on manual transcription of data from dials and scales on the observation instrument to control dials on the computer. The reading from observation instrument would appear on a dial, and operator would read the dial manually and call out the reading through voice tubes or internal telephones to another operator near the fire control computer deep inside the ship, and there the operator would rotate a hand wheel on the computer to bring a second dial on the computer to match the readings he just heard. This builds in both a time lag and room for operator error in the transmission of data from observation instruments to the fire control computer.

Not exactly true, it depends on which version you are looking at.

The final Shagekiban on the Yamato had 7 operators, (of course the US Mark 8 only had one) but the British admiral fire control clock, also had a team of operators operating it; and yes, they read off dials too.

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2. Fire control system needs an artificial horizon to detect inclination of the ship in order to effectively control gun fire in a pitching and rolling, and possibly listing, ship. American and German systems uses gyroscopes to automatically provide a continuously updated artificial horizontal reference to the fire control computer, again assuring a prompt and mostly accurate artificial horizon. Japanese system relies on human operators looking through telescopes at the horizon, and constantly turning hand wheels to keep cross hairs on the horizon to provide horizontal reference to the fire control computer. So in case of very poor visibility, due to smoke, weather, or heavy sea, Japanese fire control computers don't work because the operators can not see well enough to keep crosshairs on the horizon. Blind fire in rough sea and very poor visibility, like that which the British used to destroy the Scharnhorst in battle of north cape, is impossible for Japanese ships even if Japanese radar was up to par because without visibility, Japanese fire control systems can't compensate for pitch and roll of their own ships.

This is true.

Artificial horizons were an issue for the IJN, Gyroscopes were a lagging technology in Japan and the many variants that were produced were finicky.

3. The standard system of transmission of fire control instructions from the fire control computer to the individual gun turrets aboard Japanese ships were poorly designed. On American and German ships, the gun training and elevation were continuously autoindexing. That means the bearing and elevation of each gun can be instantly shifted from control by one director to control by another. Little time would be lost if one director is knocked out and a backup must take over. On Japanese systems the guns were not autoindexing. If control needs to be assigned to a director, or shifted from one director to another, the all guns and the associated director must return to zero degree train and neutral elevation in order to index the guns to the director, and in the process losing whatever target the director had been tracking and generating firing solution for, before the system can begin to rea quire the target. It is estimated on Japanese ships, if the director is knocked out, there would be a 1-2 minute dead space as all guns have to return to zero degree train and elevation to,synchronize with the backup director, before the backup director can begin tracking the target again. Since targeting solution improves with the amount time the director had been tracking the same target, when a Japanese warship's gun battery come back online after a director shift, the solution would be poorer than before the shift, and would have to build back up again. There is no such draw back with American and German system. Both primary and backup directors can continuous track targets and improve their individual solutions, and guns can be freely shifted from control by one to count roll by another with little loss of time and no loss of accuracy.

This is not exactly true,

Indexing on the Bismark is only for elevation and not for training - which to be honest, can be considered enough. The Japanese followed the British system (hence British ships like the KGV were not indexed) where gunnery direction is more turret controlled than centralized mast controlled; e.g. the POW shooting at the Bismark was shyt when she charged directly forward with Hood at Bismark; the water sprays made the turret range finders inaccruate (This philosophy can be seen that the KGV main range finders are only 4.6 m base length (which after this battle was upgraded to 6.75 base length) while the turret range finders are 9.25 m base length. When POW turned and so the turrets are not getting sea spray across the lenses, her firing dramatically improved.

So yes, the Japanese are following the British system; which has it flaws and benefits. The German salvo bracket fire, is very quick to straddle; the British half up half down is slower. But as the Japanese / British system are so much more turret based, in the event that the ship's centralized controls are taken out, they tend to perform better as the crews are better trained in their use. e.g. a generalization but, the South Dakota's electrical failures rendered her basically impotent; while the electrical failures on the POW did slow down her firing rate, but she did continue the fight.

Maybe it is just to say that the British/Japanese system is really for an equal strength battle line bashing each other a-la Jutland; while the American/German system is really for individual ship to ship action.

 

[chuck731]

Not exactly true, it depends on which version you are looking at.

The final Shagekiban on the Yamato had 7 operators, (of course the US Mark 8 only had one) but the British admiral fire control clock, also had a team of operators operating it; and yes, they read off dials too.

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.

I think there is some confusion generated by similar sounding names:

Admiralty fire control clock (AFCC) needs to be distinguished from the Admiralty fire control table (AFCT). The former is a compact, but manual system used in destroyers and other smaller combatants starting in the early 1920s and used through the 1950s. The latter was a much more massive, automated system used in new build heavy cruisers, light cruisers, battleships starting in the late 1920s and through to the middle of 1950s. The AFCT was also retrofitted to fully modernized old battleships and battlecruisers.

AFCC was the size of a large carbinet. AFCT was the size of a large room.

Admiralty fire control table uses mostly mechanical linkages for data transmission, the shafts being hidden under a false floor in the compartment where the table is housed.

In terms of their roles, Japanese cruiser and battleship surface fire control must be compared to AFCT, not AFCC.

There is yet more British naming confusion relevant to discussion of Japanese fire control system:

Japanese large ship surface fire control computers starting from 1920s were in fact based on yet another British fire control system - the Dreyer fire clock, which is to be distinguished from Dreyer fire control table that was used on British battleships through World war one and continue to be used on older unmodernized battleships and battlecruisers through WWII. Hood's poor shooting is partially attributable to her continued use of the WWI era Dreyer fire control table , MkIII.

Dreyer fire control clock was an commercial exercise undertaken after the end of WWI to produce something comparable in size and capability to the AFCC for export. It had no design relationship with Dreyer fire control table . The Japanese purchased the Dreyer fire control clock in the early 1920s and used it as the basis of all subsequent Japanese surface fire control systems on their large surface combatant.

No doubt the Japanese were aware of the weakness of their fire control system. The Weimar German naval attaché communicated much information about latest German fire control computers to the Japanese, as well as second hand information about the AFCT . In fact the British themselves offered to sell them the new, highly automated AFCT in the late 1920s as a bargaining chip for treaty negotiation when the relationships between the two countries had not yet become excessively tense. But the deal didn't go through.

Fire control computer of the era were enormously complicated mechanical clockwork like contraptions, and only very limited number of firms have the tool and the expertise to make them. In Japan there was only one, the Achi clock company. The capacity of the company is limited, and Japan simply didn't have the resources to manufacture large numbers of mechanical fire control computers with the same level of complexity as the AFCT , so they stuck to continuously evolving and refining the simpler system derived from the Dreyer Clock.

In their role, the Japanese fire control systems aboard most of their cruisers and battleships were comparable to the AFCT. But in their complexity, automation, and size, they were comparable to the AFCC.

This doesn't mean the Japanese system wasn't capable of competing with modern capital ship fire control system elsewhere in many situations. But it does show how lineage of the fire control system effected the design of the fire control system, and there are major design weaknesses.

Only by late 1930s did the Japanese attempt to bring their Dreyer Clock derived fire control computer up to the same level of sophistication and automation as the AFCT. The result made it into 3 ships. Yamato was one.

 

[Jura The idiot]

Discussion related to battleship duels goes on, which is great, and thanks to Lezt I became aware of this awesome web-page:

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[chuck731]

Indexing on the Bismark is only for elevation and not for training - which to be honest, can be considered enough. The Japanese followed the British system (hence British ships like the KGV were not indexed) where gunnery direction is more turret controlled than centralized mast controlled; e.g. the POW shooting at the Bismark was shyt when she charged directly forward with Hood at Bismark; the water sprays made the turret range finders inaccruate (This philosophy can be seen that the KGV main range finders are only 4.6 m base length (which after this battle was upgraded to 6.75 base length) while the turret range finders are 9.25 m base length. When POW turned and so the turrets are not getting sea spray across the lenses, her firing dramatically improved.
.

That really does not address the short coming.

But first the supposed difference between turret centric and masthead centric fire control:

In WWII naval fire controls, there are 3 components:

1. Director - which the officer in charge of gunnery use to designate targets to his guns

2. Range finder - Which receives instructions from the director on which target to look at, and determine the range to that target, as well as the range to any shell splashes that lands around the target.

3. Fire control computer - which receives continuous bearing input from the director, and continuous range input from the range finder, and computes a mathematical model of the absolute future movements of the target. It also receives inputs from the ship's own compass, knotmeters, etc, to compute a mathematical model of the absolute future movements of own ship. It also receive input from artifical horizon reference to determine the ship's pitch and roll, and generate a continuous stream of instructions to the gun turret on how to achieve correct lead angle and elevation to compensate for ship's own role and pitch to hit the target.

A director and range finder could really be anywhere. In all battleships of WWII, there are directors and range finders high up in the superstructure for primary control in long range battles, where a high location ensures line of sight over the curvature of the earth to enemy, and there are backup directors and range finders in each of the main turrets, so each turret can undertake local control of itself, or function as backup controler for all the other turrets. In a pinch, it is also possible to use the directors and range finders for secondary battery to feed the fire control computer for the main guns.

What is more, any director can pair with any range finder as situation requires to feed data into the fire control computer. They don't have to be next to each other. This is true for all WWII battleships, Japanese, German, British, or American. If all the main gun range finders were out of commission, but a main gun director is still in service, the main main gun director can pair up with the range finder in a secondary turret to continue to feed useful information to the fire control computer.

It so happens the British and Americans believed very long distance battles where the enemy is visible only from the masthead (30Kkm+) is unlikely to be decisive. So there was no need to accept the added top weight of putting a heavy long baseline range finder so high up in the superstructure. That's why on British and American battleships, while there are directors high up in the superstructure to ensure a panaramic view of the battle so targets can be better chosen, there was only a short baseline light weight range finder up top. The reason is the belief that at decisive battle range, the enemy will be visible from the turret and a big range finder in the turret would be much better protected than a big range finder at the top of the mast.

The Germans and the Japanese, on the other hand, thought the battle could in fact be decided at very long range with plunging fire, where the enemy would only be visible from the masthead. This is why their battleship puts their longest baseline range finders high up on top of their conning towers, to ensure best possible fire control input when the enemy is still hidden behind the curvature of the earth when viewed from turret level.

How each side's expectation corresponded to reality as discovered in WWII is the subject for another discussion. Suffice it to say Japanese pre-war doctrine call for fire to be opened at 34km, but Japanese expectation of hit rates at 30kms turned out to be higher than any that was ever actually achieve in battle condition by any one at 17-19 kms.

But the point here is the general layout of the fire control systems of Japan, Britain, US and Germany wasn't all that different, just different emphasis on range.

Now back to the issue of indexing. The Japanese system is poor simply because if the control needs to be transfered from one director to another, it takes a long time to do it. Furthermore, the new director, if it had already been tracking an enemy target and have been feeding data into the fire control computer, must now stop, pivot around to point dead ahead or dead astern and weight until all the gun turrets also line up in their neutral positions, before it can be trained back onto the target and begin a new firing solition. So any soliution the firing control computer had been working on it not lost, and it has to start over again. It doesn't matter if the director being transfered from and the one being transdered to is on the masthead, or in one of the turrets.

It also makes it impossible for the Japanese to have different directors simulataneously track different targets and continuously imporve firing solutions to multiple targets at the same time, and switch the entire main battery from one target to another as tactical situation needs. Instead they must split the main battery into several sub battery to simulataenously engage different targets separately.

The Japanese and Germans also emphasized dispersion and redundancy more than British and Americans. The Yamato had no less that 6 different backup main battery directors on her superstructure, one on top of the massive 15m range finder at mast top, two half way up the tower mast on each side, one over rear 10m range finder, and two on either side of the under the 10m range finder tower, in addition to the three in the main turrets, for a total of 9 main battery directors, compared to 5 on British and American battleships.

It is a pity how Yamato was given so many redundant directors to ensure combat effectivess after suffering damage, but adapted a system that made switching from one director to another so laborious and disrupting.