Estonia sinking

Discussion in 'Boat Design' started by peter radclyffe, Sep 29, 2020.

  1. peter radclyffe
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    peter radclyffe Senior Member

  2. jehardiman
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    jehardiman Senior Member

    <shrug> Shouldn't be too surprising considering the weather, ship length, and water depth. Much like the FITZGERALD, when one end is afloat and the other on the bottom, you should expect girder failure.
     
  3. sharpii2
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    sharpii2 Senior Member

    Perhaps the damage was caused after the ship sank. It could have hit the bottom of the sea hard and unevenly, causing the rend in the hull.

    IIRC, this ship had a bow section that pivoted upward, to load and off-load vehicles, which was called a "viser". This pivoted on just two points, and was supposedly broken off in the storm (it was found some distance from the rest of the wreck).

    Had this happened, the bow water-tight doors would have faced the full fury of the waves the ship was most likely steaming right into. They were probably not engineered to take these loads.

    Had the crew known the viser was gone, they might have changed course (facing the risk of capsize over the near certainty of down-flooding, once the water-tight doors failed).

    A well-placed shrill-alarm, or even a crude CCTV, might have saved the vessel. But then again it may not have. Steaming in the trough of waves, in a severe storm, is never good business--but it may have worked.
     
  4. JSL
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    JSL Senior Member

    According to a documentary I saw, a contributing factor was free surface moment (FSM). They only needed 100mm (4") of water on the deck to capsize.
     
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  5. kerosene
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    kerosene Senior Member

    I recall that it was listed for some time before the final disaster.
    I remember the morning well. mom taking me to highschool. bad weather and listening to news.

    my best buddy was celebrating the end of his military service on a cruise to Sweden and the boat he was on was 1 of the 2 that went to pick up people and life rafts.

    was a big deal here. complex mess. starting from language skill issues etc. if I recall the visor had had earlier issues of not locking properly or locking alarm giving false alarms or something similar.
     
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  6. kerosene
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    kerosene Senior Member

    here is chain of events per the accident analysis commission (my translation) 1994

    https://www.turvallisuustutkinta.fi...vestonia/SgvKlAeFL/13_Onnettomuuden_kulku.pdf

    unfortunately in Finnish.

    attached also the image of simulated path. Ship was loaded unevenly so at neutral the windward balance tank was almost full and leeward empty. thus in wind ship was a little listed already before the accident.
    Visor was lost at 01:14 they started turning right away and ship listed quickly to 15 degrees (probably not yet too flooded).

    it was fairly quick it seems faster than I recall.
    1st engine lost at 01:20 and second at 01:22 when 1st mayday call was made.
     

    Attached Files:

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  7. kerosene
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    kerosene Senior Member

  8. Alexanov
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    Alexanov Senior Member

    Free water surface create initial heel, then cars on the desk shifted to side and waves and wind finish it. Only one question - how is it possible to completely loose visor?
     
  9. sharpii2
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    sharpii2 Senior Member

    Sadly, quite easily. No offense intended for the ship builders, but the sea's capacity to destroy is practically unlimited.

    It is very possible that the ship encountered a rogue wave. This wave could have been traveling across the normal wave train that night. Then it could have hit the very tip of the bow like a bar room round-house punch.

    Kapow!

    Like a fist hitting a lower jaw, tearing the hinge part right off.

    They should design these vessels to be less vulnerable to to vehicle deck flooding and and greater than average rolling.

    This could be accomplished by installing divider walls that extend the length of the deck. These could be as high as a mere 45 centimeters, with one for every lane. Each could have scuppers at their base, spaced every few meters.

    These divider walls could serve two purposes:

    1.) they would prevent all the water, from modest flooding, from sloshing immediately to the low side.

    2.) they would keep vehicles from sliding to the low side too.
     
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  10. Alexanov
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    Alexanov Senior Member

    Who is designer of Estonia?
     
  11. jehardiman
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    jehardiman Senior Member

    As I have said before, there are no "rogue" waves, they are a statistical certainty and ubiquitous in any given seaway. What is random chance is being in the same place/time as one.
    Meyer Werft built the ship, von Tell AB the visor mechanism, but I don't think that is the real issue.
    One of the things that I have encountered during my working experience (1977 to 2018) was the effect of the proliferation of HSLA steels in the 1970s through 1990's. While HSLA properties look good, about the mid 1990's we began to experience repeated in service failures of HSLA mechanical features in the marine environment. There were many different failure mechanisms, but common to almost all was a history of a nominal in service life of a constant high-cycle low-load condition interspersed with low-cycle high-load operations. It is postulated that the high-cycle condition lead to growth of intra/inter granular defects too small to detect. These then form a stress riser in the low-cycle condition that leads to cascade failure. There are papers on this from the mid 2000's on.
    As far as I know, no parts of the bow visor fittings have been recovered, and even if they were now, the corrosion process would render microscopic inspection of the failure surface moot.
    To quote the report:
    Section 3.3 of the report which details the visor design and repairs.
    MV ESTONIA - final report CHAPTER 3 THE VESSEL https://onse.fi/estonia/chapt03_2.html
     

  12. Ike
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    Ike Senior Member

    Not surprised by this thread. I have read several articles about this. In addition to the official reports there are lots of alternative theories about it. I have seen articles in several British publications about it. There is even a wikipedia page on this. MS Estonia - Wikipedia https://en.wikipedia.org/wiki/MS_Estonia
     
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