War vessels seakeeping

Discussion in 'Boat Design' started by akuamare, May 17, 2006.

  1. akuamare
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    akuamare New Member

    I need to write a "short" paper about war ships' seakeeping (particularly for a frigate)... but I only found general information.

    The main point of the paper is broachig: causes, mathematical prediction, consequences, ...

    Could anyone help me ?

    Smoothy waves
     
  2. jehardiman
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    jehardiman Senior Member

    Modern or sailing?

    Do you understand what broaching is and what the difference would be between a modern frigate and a sailing one?
     
  3. Guillermo
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    Guillermo Ingeniero Naval

  4. jehardiman
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    jehardiman Senior Member

    To quote from one of the papers above:

    That about sums it up for the modern frigate.
     
  5. mmd
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    mmd Senior Member

    I understand the need for the specificity of technical language, John, but the quote in your post above is beyond the pale. :rolleyes: :eek::D
     
  6. Bergalia
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    Bergalia Senior Member

    I think he means 'Don't let the waves hit you side on....':rolleyes:
     
  7. akuamare
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    akuamare New Member

    Modern frigate

    First of all... THANKS for your help (specially GG... regards from Madrid. And yes, the "paper" is for the ETSIN)


    I'll "study" those proceeds, sure. I'm thinking to include and specific application, based on a X m frigate and a range of speeds and 0º-360º wave directions... :rolleyes:


    Thanks again

    Smoothy waves


    PS, a sailing frigate would be too much vessel for me... but it's an idea for the future :)
     
  8. jehardiman
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    jehardiman Senior Member

    mmd, one of my problems is that I DO understand it.....;)

    akuamare;
    It may be a better paper if you only looked at waves from say 315 to 045 relative (i.e. a wave with a relative direction of 000 is from the stern, 090 from the port to stbd, 180 is on the bow, etc.) but varied the wave length from 1/3 the length of the vessel to 4 times the length of the vessel. Then look to see if ships speed has any effect on the answer. Because a frigates length is about 1/2 the wavelength of common 11-13 second seaways, they really have trouble with broaching in following seas.
     
  9. safewalrus
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    safewalrus Ancient Marriner

    Or to put it into Seamans terms they're pigs to steer with a following sea! Don't I know it! And JEH how long is a 'frigate?' these days - some look like light cruisers (they are but they build 'em that way to con the politician and get bigger ships!)
     

  10. jehardiman
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    jehardiman Senior Member

    They are slightly smaller than the size of a WWII light cruiser at say 500' and 5000 t's. FFG-7 and La Fayette classes are ~450' LOA and ~4300 t's full load. Older ones were smaller; ~ 380' and 3300 t's full load (USCG 378's and Type 21).

    For comparison, a US Fletcher class WWII DD was 376' and 2900 t's, a UK WWII Tribal class DD was 344' and 1900 t's, a German WWII Z class was 384' and 1900 t's, and Japanese WWII Kagero was 364' and 2000 t's.
     
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