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Bismarck vs. Yamato

Discussion in 'What If - Other' started by dasreich, Aug 16, 2002.

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  1. T. A. Gardner

    T. A. Gardner Genuine Chief

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    I have a really old (written in GWBasic) program that actually does all the caluclations. Got it out of an old Warship International It calculates the trajectory based on elevation, shell (a number of pramaters here like CHR, weight, etc.) air temperature, wind, gun elevation, and such. Penetration is calculated using the US Immunity Zone Slide Rule. This is theoretical rather than actual but usually comes out within an inch or so of actual penetration.
    It might be available on line I'll have a look. I believe it was written by Nathan Orkim or some something similar to that.
     
  2. Tony Williams

    Tony Williams Member

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    That'll be Nathan Okun, who produced the comparative analysis I provided a link to previously.

    I suspect that all the programme does is look at penetration (and does that take into account that the ships are likely to be at an angle to each other, rather than exactly parallel?). From your description, it may also not take into account the greater radius of destruction of an 18" shell over a 15" one when they detonate after penetration, nor the capacity of different ships to withstand a given amount of damage (which is largely linked to displacement, as I said).
     
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  3. EnTaro

    EnTaro Member

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    In my opinion the one that spot first will win the battle.
     
  4. lwd

    lwd Ace

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    I don't agree with the ranges that are being proposed. Both US and Japanese doctrine was to fight at longer ranges. Yamato will try to fight most probably in the 25,000 to 30,000 yard range. At that range even a single solid hit from her will really hurt Bismark. Bismark on the other hand can't penetrate most of Yamato's armor at that range. I suspect that at those ranges if Yamato's shells don't detonate they have a decent chance of exiting the bottom or lower hull of Bismark.

    Also consider that while some have suggested Bismark is more resitant to diving shells Yamato's shells are specificlly designed to function well in this mode. Given their weight I think Yamato is in better shape taking diving shells than Bismark if the two are fighting each other.

    Bismark's only real hope in my opinion is that for some reason the engagement sarts at short range and stays there and that she is lucky enough to get in several telling hits before Yamato.
     
  5. T. A. Gardner

    T. A. Gardner Genuine Chief

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    The problem is that history shows that this doesn't happen. At just 20,000 yards both ships will be hull down to the horizon to their spotters and rangetakers. It is difficult to hit a ship in this situation which is why most naval actions take place at even shorter ranges. Longer range fire is possible if one is using spotter aircraft but, this actually is extremely rare except in shore bombardment situations. Most of the time, ship's captains tended to just jettison the aircraft over the side to get rid of them because they represent a huge fire hazard on board.

    Again, history is against you here. The diving shell while a serious threat is not high on the list of probables in terms of hits. Also, as shown by other actions, whether or not the shell was specifically designed for this purpose has little impact on whether diving hits are scored. If anything, by the Japanese designing their shells with this specific purpose in mind they actually decreased their overall performance. This is one major reason the Japanese 18" gun is such a poor performer for its size.

    It still comes down to who hits first. Bismarck appears to have had the historical edge here at whatever the range is.
     
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  6. ww2dude

    ww2dude Member

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    I'd like to add how well each crew were trained. As we can see inexperience has changed the tide of a battle. Also how well the Captain handles the ship in dogging shells. Then as mentioned before you have the weather factor. Rarely are ships going to fight on calm seas. And last but not least, my favorite, luck. As mentioned before luck has a lot to do as we saw with the HMS HOOD. All I can say is I like both ships so I'm really nuetral on the matter.
     
  7. lwd

    lwd Ace

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    This not correct for WWII. For instance Hood and POW vs Bismark occured at over 20,000 yards. Rodney got her telling hits on Bismark at over 20,000 yards. Warspite and the Italian BBs exchanged fire at over 20,000 yards. Some of the US BBs at Surgaua had good target solutions at over 30,000 yards but didn't open up until the range was around 24,000 yards because they didn't have lot of AP ammo. Note that British and German doctrine called for closeing the range. Spotter ac did prove problematic. However you can still see the hul of an opposing battleship at well over 20,000 yards from spotting stations on most BBs.
    I would argue other wise. Both POW and Bismark were hit by "diving shells". How high it is on the list is dependent on range and the guns involved. The fact that they are specifically disigned for diving as you say has little impact on whether or not such a hit is achieved but it may have a great impact on the effects of said hits. I believe most diving hits by non pruposly designed shells did not detonate and at leat the one POW took from what I've read didn't even hit point first. While this did have some negative impacts on Yamato's shells especailly vs Bismarks decks they had performance to spare.
    Not who gets the first hit. Who gets the frist telling hit has an advantage but Bismark has little edge there. Indeed in 42 Yamato was supose to have had a crack crew by the time of the engagment off Samar it appears to have declined probably due to lack of sea time.
     
  8. Tony Williams

    Tony Williams Member

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    I suspect that there may be some confusion over the meaning of "diving shells". The Japanese heavy shells were (uniquely AFAIK) designed to penetrate the lower, unprotected hull after diving through the intervening water. That is a different matter from a shell fired at very long range hitting horizontal armour from a steep angle, i.e. diving on to it.
     
  9. T. A. Gardner

    T. A. Gardner Genuine Chief

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    I suggest perusing this article I wrote.

    Military History Online - Capital Ship Surface Actions World War II

    The 20,000 yard measure is a good rule of thumb. Beyond that it is mostly pure luck to get any hits. The discussion in excrutiating detail given in Naval Ordinance and Gunnery NavPers 16116-B is also very illuminating on why with optical rangefinders this range is about the maximum for accuracy.
    As for the diving shell, these hits did happen. But, may assertion was that the Japanese in designing a shell specifically to follow a short predictable underwater trajectory were making a very bad trade off.
     
  10. lwd

    lwd Ace

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    OK not a bad summary. Missing some useful details for this discussion and the analyis is debateable.
    It's mostly a matter of luck getting hits at any range. As the range increase it just affects the probability. However hits at longer ranges are potentially more devestating. This proved true at Denmark straights, Rodney & KGV vs Bismark, Warspite vs Giulio Cesare, and Casablanca. Surigao Strait was so one sided it's hard to tell.

    Furthermore both Japan and the US as well as other powers for that matter were working on methods to increase the accuaracy at long range. Airial observaition and radar being the two primary ones used.

    For shells below 18" in size I'd agree with you. For the 18" shells it's more difficult to say since even with the tradeoffs they were still very deadly vs most if not all likely opponents.

    If this postulated encounter occures during daylight with any decent amount of visibility I have little doubt that Yamato would launch a spotting plane and probably open the engagement at over 30,000 yards. Lacking that she would open at any range under 30,000 where she could get a decent view of her opponent.

    Don't both of these ships have a radar capable of reporting range by the way?
     
  11. Za Rodinu

    Za Rodinu Aquila non capit muscas

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    Pardon my ignorance on everything naval, but isn't a defined stretch of water before the hull to get at the underwater hull, a rather narrow target? Also wouldn't bulging and other anti-torpedo protection do something to minimize the effect of a hit?
     
  12. lwd

    lwd Ace

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    Depends a lot on the distance or actually on the decent angle of the shell. At 45 degrees its as wide as the ship is deep at lower angles it's wider. Note that said shells are still designed to be effective if they hit head on, although as noted there is something of a decrease in effectiveness. A shell that can penetrated a battlships belt armor isn't going to be effected too much by the TDS or bulges. A further note is that once the angle of decent gets low enough the shell may skip rather than "dive" so the band dissapears at that point.
     
  13. T. A. Gardner

    T. A. Gardner Genuine Chief

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    The Bismarck had two seetakt 53cm wavelength radars on board mounted on the faces of the primary and secondary main battery rangefinders. These radars would give a reasonable range to the target but were essentially useless in bearing data being too wide beamed to be able to sufficently resolve bearing to a useful level. Additionally, they were not tied into the fire control system so their data had to be manually entered. They do make a useful backup to the optical rangetakers but that is about it.

    The Yamato did not get a useful fire control radar until early in 1944 when some of the first production 2 Gô 2 Gata 4 Kai S sets became available. This set operated at 10 cm and gave excellent range data and fair bearing data. But, like the Seetakt set it was not tied into the ship's fire control system so any use of it had to be manually input. An additional problem was that the radar operator was not co-located with the optical rangetakers meaning that communications and coordination would be more difficult.

    So, essentially both battleships would be relying on optical rangetaking for fire control with radar playing a role of giving a second set of range data to back up the optical inputs.
     
  14. T. A. Gardner

    T. A. Gardner Genuine Chief

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    On the Yamato there was a deliberate attempt to minimize the diving shell threat in the torpedo defense system. This was done by carrying the belt down to the double bottom of the ship and slanting it inward to create a fairly deep defense system. The Japanese erred in leaving this space void instead of liquid loaded however. With the Bismarck because the ship has a fairly wide beam the torpedo defense system is quite deep and there is an internal bulkhead at the back of the system that is fairly substancial. The Germans also have their system liquid loaded.
    In both ships the system used is sufficently deep that most diving shells should fail to penetrate the defense system. In the Prince of Wales' case the one hit on her by Bismarck below the waterline failed to penetrate her relatively shallow defense system and instead caused flooding in the torpedo defense system itself.
    The main reason the shells lack a large amount of penetration is simply that their velocity decreases extremely rapidly upon entering the water. Even following a reliable underwater trajectory, the Yamato's shells will not travel all that far after entering the water and will lack the penetrative power of an above waterline hit.
     
  15. mac_bolan00

    mac_bolan00 Member

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    first, i believe it was the fuso that emerged from the straight only to be destroyed by US BBs in classic line formation. the yamashiro was torpedoed while making the passage.

    now this is where my knowledge of radar-assisted fire ends. beyond visibility during the day and at night, can fire controll radars detect the report from the last shot? it could be a direct hit, a dud, or a miss, producing your 150-foot water fountain. i want to know since, if you don't see the report on the first shot, you can't fire a second.
     
  16. skunk works

    skunk works Ace

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    I believe you have it reverse there mac. Fuso was sunk by torpedoes from USS Melvin (so the popular story goes) inside the Straight, Yamashiro was hit by virtually everyone as she attempted to emerge from the East side.
     
  17. mac_bolan00

    mac_bolan00 Member

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    i'll take your word for it for now. the "turkey trots to water" article HAD it in reverse. and yes, the maryland managed to pick up west virginia's shell splashes on her radar.
     
  18. T. A. Gardner

    T. A. Gardner Genuine Chief

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    This weekend I'll hook up a new scanner I got. I will then put up some pictures of what targets and shell splashes look like on the US Mk 8 FC radar scope. Unfortunately, I don't have any for Seetakt or the 2 Gô 2 Gata sets but I know these used A scopes rather than a PPI type display.
     
  19. lwd

    lwd Ace

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    Here's a link to a good account of the ends of the Fuso and Yamashiro.
    FUSO
    World war two radar in it's most advanced state could detect shell splashes well beyond 30,000 yards but I believe could "detect" hits only by the absence of the splashes.
    There's an analysis of the US BB gunnery during that action at:
    Performance of US Battleships at Surigao Strait
    that's also worth taking a look at.
     
  20. lwd

    lwd Ace

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    AS for diving shells apparently it's a lot more complex than I thought. See the thread at:
    Type 91 diving shell
     
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