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japanese diving shells


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#1 alberto ricart

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Posted 11 June 2007 - 09:07 PM

one topic I can find little informatio on are the japanese diving shells. during the battle of the komandorski islands the cruiser salt lake city took several hits which caused flooding. I can`t find information if these were underwater hits by japanese shells, but it does seem likely.in which case these shells would have performed as designed. since long range duels of this nature were rare in the war but are common in my weekend battles, I wonder if anyone knows more about these shells and how their effects could be incorporated into the gamealberto

#2 Cpt M

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Posted 12 June 2007 - 12:57 AM

The 'suichudan' or underwater shot was an attempt by the Japanese to maximize the effects of near-misses by large caliber shells. The theory was that a round falling short would lose its ballistic cap and take on a flattened trajectory towards the hull, resulting in a hit below the waterline. To work, the method required a shell design with a flattened head and a delay in the fuzing to compensate for the time underwater. To this end the Type 91 AP shell was designed in 16", 14", and 8" guns. There were some major disadvantages. First, it was only effective in a relatively narrow range band (only a few thousand yards). Second, the Japanese considered this technique so secret that the necessary peacetime training (to optimise the firing methods) was never carried out. Postwar analysis by the US Naval Technical Mission was doubtful of the effectiveness of the 'suichudan' method and, in fact, noted that by increasing the fuzing delay, the net effect was to decrease the effectiveness of their AP shell. Additionally, analysis of damage to US ships does not seem to support the claims for 'suichudan.' Given the limited tactical effectiveness, the lack of training, doubtful damage effectiveness, incorporating them into the game does not seem warranted. (Source: Kaigun: Strategy, Tactics, and Technology in the Imperial Japanese Navy 1887-1941; Evans and Peattie)

#3 Jim O'Neil

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Posted 14 June 2007 - 07:44 PM

One of SLC's near misses was just that, a shell that exploded close alongside.The other *may* have been a diving shell that worked right. The CL BOISE was also hit by one off Guadalcanal, and I think there was one other case...The probabilities are so low (3 times in a war) as to be ungameable... AND the effects were not anywhere so lethal as intended. BOISE's shell ended up in a Magazine, which she survived, although I believe (from memory) almost all the magazine and turret crews were killed.Note that such hits happened twice in the battle between HOOD ?PoW and BISMARCK. Both BISMARCK and PoW suffered diving hits.Note that the flat nose made penetration poor on thick armor, compared to other navies shells.

#4 Radek Gozdek

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Posted 20 June 2007 - 01:32 PM

For all war, was only one diving shell hit - at the battle of the komandorski islands.

#5 alberto ricart

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Posted 21 June 2007 - 11:43 AM

Thanks for your commentshowever I still have some difficulty letting it go.it is true that these underwater hits were rare, however it seems that to get this type of a hit the ship needs to be at enough distance to allow the shell to fall at enough of a steep angle. combat at long ranges like at the komandorsky islands was a rare event. maybe the battle of java sea, one 8 inch hit. therefore one hit at the komandorskies does not seem so little anymore. specially when the hit flooded the magazine and crippled the ship. It seems the shell did what it was supposed to do.the only battle where the japanese battleships fought a long range battle was leyte. I do not know how the shells performed there, and that was not what these ships were designed to do anyway, firing on destroyers and carriers.one of the enjoyable things about gaming the war in the pacific surface battles is the asymmetry of the tatics, at these shells were part of it, with their armour penetration problems.it seems the battles battleships and cruisers were supposed to fight never happened in real life, but at my home they do seem to happen on saturday nights. alberto

#6 Cpt M

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Posted 21 June 2007 - 01:16 PM

The problem with the 'suichudan' or underwater shot is the very narrow parameters of use and the randomness of its effect. To work, a shell had to enter the water at certain narrowly defined angle and within a certain distance from the target. These requirements result in the effect only coming into its own in a very narrow band of ranges (depending on the gun in question) and for rounds that fall short within a specific distance. And, even if all the parameters are met, the 'effect' may not even work due to a host of other variables. Based on the combat in the Solomons and the experience of the Komandorski battle, historians have only identified 3 incidents which may (and I stress, MAY) be attributed to an underwater shot. Given the limitations involved and the randomness of the 'effect,' this would be impossible to realistically model in a game such as GQ3.

#7 Jim O'Neil

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Posted 22 June 2007 - 10:37 PM

I think Critical hits does a good job of modelling this unlikely but potentialy dangerous hit.




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