ISO 12215-5-2019 kCH correction factor

Discussion in 'Class Societies' started by Midja, Apr 26, 2023.

  1. Midja
    Joined: Oct 2022
    Posts: 20
    Likes: 0, Points: 1
    Location: Norway

    Midja Junior Member

    Hi guys,

    As always ISO gives more questions than answers.
    I am analyzing ply by ply boat bottom made of fiberglass (core isn`t used), sketch attached.

    Example.jpg

    I have stumbled across Annex A, chapter "Case where round bilged and hard chined panels act as "natural" stiffener, page 32.
    On page 33 there is chapter connected to hard chined sections and correction factor kCH which enlarges width of panel.
    My example has natural stiffener as chine between bottom and side, then top hat longitudinal and keel, which is not example from figure A3 on page 34.

    Main question is this chapter/correction factor kCH applicable for my case?
    In my opinion no, because in description there is this sentence "For hard chined sections the length b used for calculation shall be taken as the actual b between chines". I have also longitudinal top hat, not only chines to support whole section.

    Thank you for your opinion!
     
  2. Alan Cattelliot
    Joined: Jul 2021
    Posts: 506
    Likes: 213, Points: 43
    Location: La Rochelle (Fr)

    Alan Cattelliot Senior Member

    Hi Midja,

    in this case, the paneling could be taken as :

    upload_2023-4-27_10-7-27.png

    Red-Green : Apply Kch
    Blue : omega with associated plating
    Orange : omega without associated plating if the aspect-ratio do not exceed table A.12 requirements. If not, split into two panels and apply Kch
    Violet : If (Orange) is an omega, do not apply Kch. If not, apply Kch

    Hope this makes sense. Cheers,
     
  3. Midja
    Joined: Oct 2022
    Posts: 20
    Likes: 0, Points: 1
    Location: Norway

    Midja Junior Member

    Thank you,

    What do you mean by omega? I`ve lost you at that term.
     
  4. Alan Cattelliot
    Joined: Jul 2021
    Posts: 506
    Likes: 213, Points: 43
    Location: La Rochelle (Fr)

    Alan Cattelliot Senior Member

    Sorry I wasn't clear enough. I've used the term omega to designate a stiffener which has the shape of an omega, with flanges and web. Like the "TOP HAT" designation in your drawing.

    upload_2023-4-27_10-41-37.png
     

  5. Midja
    Joined: Oct 2022
    Posts: 20
    Likes: 0, Points: 1
    Location: Norway

    Midja Junior Member

    Thank you, all clear!
     
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