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Yamato verses Iowa

Discussion in 'Naval Warfare in the Pacific' started by Ron, Oct 3, 2000.

  1. USS Washington

    USS Washington Active Member

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    I second this, while the Mk. 6 16" gun had a slightly lower muzzle velocity than the Iowas Mk. 7, however, at the range that Washington would've pounded Yamato during the Battle off Guadalcanal, this would be irrelevant, especially since she too used the Mk. 8 "super heavy" round, and infact, in a longer ranged duel, the Mk. 6 might have had a slight edge over the Iowas guns in regards to penetrating deck armor, as the shells would have dived at a steeper angle due to losing energy faster. Now combined with also having superior radar fire control, the ability to shoot with accuracy even while making radical maneuvers, better damage control, and with the inclined STS armor, which as you mentioned in an earlier post, might actually provide better protection than Yamatos, I strongly believe that the South Dakota and North Carolina class' could also have a strong chance at beating Yamato.
     
  2. lwd

    lwd Ace

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    If you use turning circle as a measure of manouverability I'm not sure that the Iowa was more manouverable than Yamato. From what I recall the latter had a pretty tight turning circle. Of course making repeated tight turns bleeds off speed and Iowa had more speed and probably better acceleration. It would be interesting to see the relatiave turning circles posted although we may not have them for the same speeds.
     
  3. Bucketfoot-AL

    Bucketfoot-AL New Member

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    I have always found this photo of Yamato dodging bombs and torpedoes in the Inland Sea in March 1945 to be quite remarkable. She is undoubtedly making close to her maximum speed of 27 knots going into the turn ...

    Maybe its the angle of the photo but G-D it doesn't it look like she almost made a 90 degree turn on the dime???

    I am not knowledgeable about the US battleships in this regard, but everything I have read indicates that Yamato and Musashi had extremely tight turning radii for such large ships ... due to their hull designs they were incredibly stable ships (though I don't know if that would be a factor re the turning capabilities...)

    http://www.battleshipyamato.com/index.album/yamato-bombed-in-the-inland-sea-march-1945?i=93&s=1
     
  4. Bucketfoot-AL

    Bucketfoot-AL New Member

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    Yamato was hit by several torpedoes from USS Skate in 1943 and shipped 3,000 tons of water, if I recall correctly. The attack demonstrated that at the point where the upper half of her armor belt joined with the lower half there was a design flaw - this resulted in a total failure of the main armor belt system due to a flawed joint between the upper and lower side protection belts.

    The repaired area was strengthened with some kind of cross-buttressing of the joint, but of course that could not be done to the rest of the ship in the middle of the war. Someone explained it to me once, but I am having a hard time finding the reference right now ...
     
  5. Gromit801

    Gromit801 Member

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    True, just look at the Shinnano. Four torpedoes hitting the seam of the two armor belts, and belly up.
     
  6. lwd

    lwd Ace

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    Although to be fair she was not fully manned and the decision to continue at full speed didn't help either.
     
  7. Takao

    Takao Ace

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    I believe that Shinano was also incomplete, and her compartments not pressure-tested to insure that they were watertight.
     
  8. lwd

    lwd Ace

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    according to:
    http://www.brighthubengineering.com/marine-history/115666-ijn-shinano-japans-largest-aircraft-carrier/
    Using some what different words it's confirmed by:
    http://wikimapia.org/2226023/Wreck-of-the-HIJMS-Shinano-%E4%BF%A1%E6%BF%83
    and
    http://ww2db.com/ship_spec.php?ship_id=19
    http://www.avalanchepress.com/Shinano.php
     
  9. SymphonicPoet

    SymphonicPoet Member

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    I believe one of the factors on turning circle is beam to length ratio. A finer ship generally creates less friction for its mass in the direction parallel to the keel, thus making it potentially faster, but considerably more in the direction perpendicular to the keel. I figure trying to turn a long slender ship is perhaps akin to trying to push a wall through the water sideways. The water displaced by the turning motion has a LONG way to travel to get out of the way. Hopefully someone can correct me if I'm wrong, but I'm about to walk into the wonderful land of surmise and half-remembered hearsay. Some simple vector arithmetic tells us a few things. Any ship turning is necessarily subject to asymmetric forces. There are at least two possible sources. (Probably only two.) Hydrodynamics and aerodynamics are, of course, closely akin. The rudder will provide some hydrodynamic force. Among other things it will create a greater drag load on one side of the ship than the other. This drag should tend to "pull" the bow in the relevant direction through tension along the length of the ship much as if you'd tied a rope to the rudder. While the moment arm formed by the rudder draws this drag off center, helping to turn the ship with leverage, the fundamental direction of the "drag" force should still be precisely parallel to the direction of travel, though with a negative value.

    The rudder could have other effects, of course. In a compressible substance like a gas turning the rudder would create a certain amount of "lift" by distorting the shape of the hull. This lift should push the entire hull perpendicular to the course of travel in a direction opposite that to which the rudder has been turned. Water is, of course, not air. It's not compressible, for instance, which means it behave rather differently in many important ways. Rudders don't seem to make ships go sideways, thus I will take the liberty of assuming that this "lift" is either absent (due to water) or extremely weak. It should be testable, but I have neither the equipment nor the knowledge. For our purposes, I would guess that the "drag" is the most important effect of the rudder on motion for ships acting entirely inertially. Like all assumptions, this one is liable to be quite wrong.

    I have heard several times before that a ship turning does not actually turn "by the bow", if you will, where the bow draws the ship through the turn (as hypothesized above), but rather the stern actually kicks out away from the direction of the turn and "pushes" the entire ship through the turn. A glance at basic navel architecture will reveal that the rudder or rudders are quite regularly directly astern of the screws. Almost always, in fact. This should provide another effect that could help to explain this motion and further help to explain why fine ships are more reluctant to turn. Put simply, the rudder vectors a portion of the thrust provided by the screws out of the axis of the keel. This thrust is a positive force acting partly or wholely perpendicular to the keel and at the maximum possible distance from the center of mass. (At the end of the longest possible lever.) Such a force SHOULD spin the ship by the keel in the direction of application. (Turn the rudder left or port and the thrust pushes the stern starboard and thus the ship turns to port.) However since this force is acting perpendicular to the keel it must counter the hull drag . . . of a ship going sideways through the water. A long "fine" ship, like Iowa, will have a lot of this. A beamy ship like Yamato will have less. A Popov battleship will have much less still.

    The "stable gun platform" business is a separate issue related to a ship's metacentric height and roll period. (Which is rather complicated and I won't go into it here, which is just as well, since I'm a fairly rank layman.) Whole different kettle of forces acting in entirely different plains. The terms here are "delicate" and "snappy" but I'll leave you to some independent study.

    Anyway, it only makes sense that Yamato could turn tighter. Fundamentally the same reason Yorktown outdid Lex in the same department. (And battleships generally outturn destroyers, as I understand it.) Yes, that's a heck of a picture of a ship that surely appears to have just done a ninety under power at speed. She would appear to have ripped a hole sideways through the water.

    Thank you for this brief bit of conjectural indulgence. Please feel free to edjumicate me properly if you happen to be in possession of a fuller or better understanding of the facts and theories.

    Now back to your regularly scheduled A-grade AP shell-storm.
     
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  10. Bucketfoot-AL

    Bucketfoot-AL New Member

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    Thanks Symphonic Poet! Pure poetry! :D

    So the extra-wide beam and flat bottom of Yamato was not only useful for accessing shallower ports and givng the ship extra stability in all manner of weather, but also had a positive effect on the handling.

    Also remember that her "bulbous bow" undoubtedly had a part to play here as well .....
     
  11. Bucketfoot-AL

    Bucketfoot-AL New Member

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    Well, maybe not quite. Since my initial post I read that the Skate's torpedoes that hit Yamato were set (for some reason) to run shallow as for trageting a destroyer, hence their (accidental) success at hitting the seam in the armor belt.

    Torpedoes targeting battleships were of course set to run 18-22 feet deep (someone help me here) so that although Musashi took 15 torpedo hits (plus 2 more duds) her citadel was not flooded. (Though the front third of the ship was swiss-cheesed as the armor was thinner there).

    So by a quirk, this significant design flaw may have been just far enough up on the side to prevent it from being automatically catastrophic.

    Yamato took anywhere from 18 - 22 torpedoes off Okinawa, so there was no armor belt on earth that could have bought her more time ...
     
  12. belasar

    belasar Court Jester Staff Member

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    While that was true, a lower number actually had her heeling over and when some were incoming to her relatively undamaged side at least one bridge officer was hoping for a hit there to counteract her list. Her centerline bulkhead preventing her shipping water to even her list.
     
  13. SymphonicPoet

    SymphonicPoet Member

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    Not sure what effect, if any, a bulbous bow has on a ships turning circle. I know they help to reduce hull drag. I believe they produce a waveform that is more or less in the opposite phase from the wave form created by the cutwater of the bow, thus partially canceling the bow wave and reducing wake turbulence and consequently hull drag. Wikipedia has a decent article on the bulbous bow for those who want a little detail. Anyway . . .

    Yes, certerline bulkheads can be problematic. I see to recall Lusitania's quite rapid demise was, in part, a result of asymmetric flooding along starboard compartments isolated by long longitudinal bulkheads. (I have a theory that Lucy and Titanic could each have survived the damage the other received.)
     
  14. Bucketfoot-AL

    Bucketfoot-AL New Member

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    The real problem was that the pumping control room was taken out by a bomb fairly early on so that the starboard torpedo blisters could no longer be flooded as the torpedo hits to the port side of Yamato accumulated.

    Hence the decision to flood her starboard engine room, which was not nearly as effective as flooding the blisters would have been to help her regain her trim. In any event we are only talking about buying her time given the punishment she absorbed.

    6 of the 9 torpedoes that hit her starboard side were from the late arriving Yorktown flight of course, so they just tore out her bottom due to her list to port and merely hastened the inevitable.
     
  15. lwd

    lwd Ace

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    From what I recall belt armor wasn't really designed to help vs torpedoes. In many cases torpedos would hit battleships beneath the belt armor if set properly. I seem to recall reading that Skate's captain thought that by setting the torpedoes to run shallow he would increase the flooding of course he didn't think he was shooting at a converted battleship either.
    This document might be relevant to the issue:
    http://www.navweaps.com/index_tech/tech-047.htm
     
  16. Gromit801

    Gromit801 Member

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    What did the Skate shoot at? If you're talking about the Shinano, that was Archerfish.
     
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  17. TiredOldSoldier

    TiredOldSoldier Ace

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    IMO that NavWeaps report is unfair to the Pugliese system, the Gemans did some extensive testing on the hull of the incomplete Impero and the system performed pretty well. Both Vittorio Veneto and Littorio took a number of torpedoes during their career, the problems Littorio had at Taranto had more to do with pumps failures than with the Pugliese system. On the smaller WW1 conversions lack of pace prevented creating full implementation (and the conversions were a typical exampe of bad Italian "recycling" of hopelessly outdated weapon systems, one can poosibly understand the first two as a "political" move to counter the Dunquerques withuout triggering an all out battlleship race but the Dorias were a waste of money.
     
  18. lwd

    lwd Ace

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    Thanks for the correction. I was in too much of a hurry reading a post above about Skate firing at Yamato and got things mixed up. Apologies to all.
     
  19. ickysdad

    ickysdad Member

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    Actually I meant just the face plate not the whole turret. Now it wasn't you but I think someone mentioned that the USS Skate hit IJN Yamato with 3-4 torpedoes in December,1943 but according to Garjke & Dulin's "Axis battleships of World War Two" pages 54-55 just one torpedo hit and another source M. J. Whitley's "Battleships of World War Two" on page 213 says the same thing. However I haven't found any primary source per any damage control report on this.

    edit..
    I forgot the US Technical Mission to Japan also states that just one torpedo from Skate hit Yamato.It still is not technically a primary document,the original damage report would be but it certainly can be considered more authoritative then any secondary source. It goes onto say the switch from TNT to Torpex had already occurred so the effect was more like in the area of 900-1200 lbs of TNT in effect.
     
  20. Takao

    Takao Ace

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    Probably generalizing the Skate's action. The USS Skate fired her 4 stern torpedo tubes with a 1 degree spread and a depth setting of 10 feet. One definite explosion was heard, followed by one muffled explosion. Her log further states that it was too dark to determine results. The log also indicates that the Skate was unaware of what her target actually was, as it was a night attack with first contact being made by radar, and it was too dark to make out targets distinctly.

    Skate's War Patrols, see pages 7-8 of her second War Patrol(pages 32-33 on the ISSUU reader)
    http://issuu.com/hnsa/docs/ss-305_skate


    All I have ever heard was that one hit was made, but combinedfleet.com mentions an unnamed POW report stating that there were two hits.
     

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