Bulkhead Tabbing at Chines

Discussion in 'Fiberglass and Composite Boat Building' started by weldandglass, Aug 6, 2017.

  1. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    No real reason to go to solid laminate at the chine, that I can see, in a lightweight skiff.
     
  2. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    I agree with Mr Efficiency.
    Lloyd's, like any other Classification Society (CS), makes recommendations on how they consider solving some problems. In order to help the designer, they indicate certain constructive details, many of them based not only on calculations but also on the experiences of their inspectors when studying large numbers of accidents.
    Any CS says that the designer can pose the solution that he prefers, as long as it justifies that it is adequate. The advantage of following the rules of a CS is that you save many calculations, submission of documentation, various justifications, etc. and you can be sure that your structure will be correct to, for example, to get permission to build a boat (in many countries it is mandatory to obtain permission from the Maritime Administration to build your boat) or get insurance at a not too high price.
     
  3. gonzo
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    gonzo Senior Member

    It makes no sense to use Loyd's or any other Classification society for a small skiff. They are outside of their calculation limits.
     
  4. gonzo
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    gonzo Senior Member

    Classification societies do not cover small skiffs.
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    I don't think you need worry, in any case are you following plans that specify "no sandwich" at the chine, keel etc ? The idea of eliminating foam cores where high loading could crush the foam under a thin laminate, can be countered by increasing outer skin laminate in those areas. Might not be so easy with your construction method, though.
     
  6. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    Yup, that's it.

    And it makes no sense to make the chine structure discontinuous at WTBs. It is illogical and not structurally sound either!
     

  7. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Thank you Mr. Efficiency. I get it now.. for high loading where the foam could be crushed or deformed by weight from above or dynamics from below. Wow! That'd be a lot of load on an 18' boat to require solid glass chine (but I am only guessing). My designer has spec'd high density foam and/or extra inside laminations for high loading areas where any crush concern related to beams exist. They aren't really the same as the downforces would not be directly onto another chine, but within the panel itself (if that makes any sense). I really wasn't asking due to any doubt about his design, but more for personal edification. And this is why I didn't care to bring his name into this muddy thread.

    There is no sandwich in the for'd keel section of my boat, so the drawings bore out some similarity which drove my curiousity. I just wanted to understand the purpose of laminating solid plies at the chine (lots of work it appears). In my boat, the solid for'd keel section is being done for construction simplification to avoid having poor hand laminations over core-also lots of work!

    Thanks to the OP as well for the interesting topic and my apologies if I seem to have hijacked (was not the intent).
     
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