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  • Question about different ways of sinkings

    Hi to all

    Hope it's the right forum to ask and that someone can answer this:


    As per documentaries, BBs Bismark and Yamato -and other warships-capsized when/before/during they sank.

    But the Passenger Liner Titanic, and most other civil ships, started to sink with either the bow or the stern before they went down.


    Why this?
    I do realise that the kind of damage below the waterline has an influence on this, but still it seems that every military ship capsized, while others sank stern/bow ahead.

    And question no. 2: (just asking coz i'd like to know wether the naval pc games are accurate)

    How many torps does it take to sink a DD, CL, CA, CV, BC, BB; and how long until it goes down?

    Looking forward to yours comments.

    Wish you all the best for the coming week. Take care.

  • #2
    How many torps does it take to sink a ship? One, if it is big enough. That's not being sarcastic, though. Have a big enough warhead, like a nuke, or produce a big enough disturbance like a Mk 48, and it tends to do the job. I think the biggest ship I've seen a Mk 48 take out was the old Oklahoma City cruiser. Split it in half, if memory serves, which is what the Mk 48 is suppose to do.

    Quick lesson on ship building. There are two conditions known as hogging and sagging. Sagging occurs when the ship is supported by the water at the stern and bow but not midships. Hogging is when the ship is supported at midships but not the stern or bow. On the small scale, this happens thru the life of the ship, as it travels the water in troughs and crests.

    What a Mk 48 does is produce a huge bubble under the midships. EXTREME hogging occurs as the force is directed to the midships but not the bow or stern. The force dissipates, the ship goes to EXTREME sagging as the bow and stern are supported by the water but not the midships. The keel cracks, the skin rips apart, the ship is torn in two. (this is my interpretation of seeing the pictures and knowing about ship construction).

    If the warhead is a nuke, then it just produces one huge hole in the ship that no one can patch.

    As far as merchants and warships, sinking and capsizing. First, there is compartmentization and then there is luck of the draw. Warships have many more compartments than merchants to prevent castrophic damage from flooding. In a merchant ship, one needs larger spaces for cargo and passenger comfort; they aren't expected to sail where people are shooting, well, not generally.

    But there have been merchants which have capsized to a degree. The Andrea Dora comes to mind. The Eastland. The Normandie. Improper balance in a situation which gives to a dangerous list and the ship goes topsy turtle.

    And there have been warships that have gone down by the bow or the stern. The Antelope. A MOD Kashin. The ex-Buchanan.

    Just because one is a merchant or warship does not decide how it will sink if it does.
    -------------------------------------------------
    ("She's sinking. Going, ..... going.......GONE!"--Landon watching their spacecraft, the "Icarus", sealing their stay on the Planet of the Apes, (w,stte), "Planet of the Apes")

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    • #3
      Originally posted by SnowLeopard View Post
      If the warhead is a nuke, then it just produces one huge hole in the ship that no one can patch.
      Well there was a nuke test (I don't remember the name of the nuke test) where they tested a nuke against ships. The ships survived the blast and did not sink. The only way a nuke can sink a ship if it explodes on contact with the ship's side.

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      • #4
        Originally posted by Blademaster View Post
        Well there was a nuke test (I don't remember the name of the nuke test) where they tested a nuke against ships. The ships survived the blast and did not sink. The only way a nuke can sink a ship if it explodes on contact with the ship's side.
        That was Crossroads.

        Otherwise, however:

        A:Able was an airburst of 21 KT's. Baker was also 21 KT's and underwater burst. Neither was a direct hit.....and each test did sink some ships.

        B: Nuclear torpedos can easily be 200 KT's though probably more in the range of 15KT. That is, allied numbers put such at 5-15, USSR torpedos are placed at similar numbers but an ASW weapon such as the SS-N-15, 16 were placed at 200 KT.

        C: You better believe that if someone is using them, they are planning to have a direct hit or what constitutes a direct hit in modern torpedo terms.

        We've come quite a distance since 1946.
        --------------------------------------------------
        ("Listen, Colonel Pupik, we've come a long way since World War Two. If that bomb goes off, it won't only take out the Israeli's but your family wherever they are in the Middle East."--USAF Col. Stevens, (w,stte), "Prisoner in the Middle")
        Last edited by SnowLeopard; 06 Jan 08,, 08:34.

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        • #5
          I think SnowLeopard did a pretty good job describing much of why it is more likely that warship will capsize than a commercial vessel. I will stick my neck out by saying that it is most likely that a ship will sink by the bow and stern almost soley because the flooding is concentrated in the bow or stern. I also agree that it is less likely in a warship due to superior compartmentalization. I do not know if in the cases where it occurred, it was because hull and bulkhead failures caused by battle damage or that stress related failures of the hull or bulkheads concentrated flooding in on end or the other, but it seems like a reasonable assumption.

          The reason for my assumption, and the reason for the preponderance of capsizing, can be found in a discussion of metacentric height and what happens to it as a ship sinks. See a reasonably short and very good discussion of it at this link: Metacentric Height The very short version is that a ship's center of buoyancy is lower than its center of gravity. The greater the distance between the two, its metacentric height, the greater the righting moment. As a ship takes on water, the center of buoyancy rises in relationship to the center of gravity. Once it is above the ship's center of gravity, the ship will turn turtle, if not by itself, then if a butterfly lands on one side or the other.

          The only thing that I would add to it is that as the ship sinks, it is extremely unlikely that it will do so on an even keel. So, as the waterline raises to the main deck with the rail on one side even a few inches higher than the other, this difference will both encourage the capsize and determine the direction that the ship will roll. Of course, this is a rather broad comment that may not be entirely true when applied to a specific sinking.

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          • #6
            Originally posted by SnowLeopard View Post
            What a Mk 48 does is produce a huge bubble under the midships. EXTREME hogging occurs as the force is directed to the midships but not the bow or stern. The force dissipates, the ship goes to EXTREME sagging as the bow and stern are supported by the water but not the midships. The keel cracks, the skin rips apart, the ship is torn in two. (this is my interpretation of seeing the pictures and knowing about ship construction).
            I suggest reading The Response of Surface Ships to Underwater Explosions for anyone who is interested in the subject.

            Basically, since liquids are incompressible, most of the explosion's force is retained. About 33% of the energy is transmitted immediately, 13% after the bubble's first expansion/contraction, and a final 17% from the second expansion.
            Pressure waves that miss the ship may still have an effect, by reflecting off the surface or the seabed.
            So if your systems (including hull members) can take the shock, and the hull plating can deform without failure, you're good to go. Otherwise, I hope you can swim.
            We distinguish ourselves from our enemies by our treatment of our enemies. - John McCain

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