Foam core thickness and density

Discussion in 'Materials' started by Willallison, Jul 29, 2002.

  1. Willallison
    Joined: Oct 2001
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    Willallison Senior Member

    Here's a "how long's a piece of string" question for you...
    Can anyone give me an estimate of thickness and weight (kg/sq.m) for foam core panel required in the construction of a 30-odd foot powerboat.
    I have 2 boats in mind - Option 1, some details of which can be seen in its own thread on this web site.
    The other is about 11m LWL, 3.7m beam, displacement 5000kg, top speed 30+ knots, inboard power.
    I only require the info for rough weight estimates at this stage.
    Even better - an on-line source of where I might be able to work this stuff out......
     
    Willallison, Jul 29, 2002
    #1
  2. BrettM
    Joined: Apr 2002
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    BrettM Senior Member

    Try
    Bottom 11.8kg/sqm 22mm (~15mm core 80kg/cu.m)
    topsides/deck 9.3kg/sqm 18mm (~12mm core 80kg/cu.m)

    This is some generic data I had for a 30'x10'4" beam 4000kg boat

    Obviously, it depends on how long your string is... and what is has to do...

    brett
     
    BrettM, Jul 29, 2002
    #2
  3. Willallison
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    Willallison Senior Member

    Thanks Brett.
    I assume the numbers you've given are for normal glass encapsulated foam - nothing too fancy.
    They'll give me a good start, thanks again
     
    Willallison, Jul 29, 2002
    #3
  4. BrettM
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    BrettM Senior Member

    pretty much and E-glass foam laminate. Nothing too fancy.
    Brett
     
    BrettM, Jul 29, 2002
    #4
  5. Polarity
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    Polarity Senior Member

    Polarity, Jul 30, 2002
    #5
  6. Willallison
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    Willallison Senior Member

    Yes thanks - I did see that. There is a fair bit of general info around on this type of construction, I was after more specific examples of just how thick and heavy the laminates should be for a particular sized boat.
     
    Willallison, Jul 30, 2002
    #6
  7. Jeff
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    Jeff Moderator

    You might also want to email Trevor Gundberg directly - Trevor.Gundberg@diabgroup.com - and see what example and quick calculations he can supply you with. I've found Trevor to be a great person to deal with.

    Maybe we will also get him to put together a follow-up article for us this fall with more specific examples of prelim calculations and a few more detailed cross reference charts.
     
    Jeff, Jul 30, 2002
    #7
  8. Willallison
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    Willallison Senior Member

    That sounds fantastic Jeff.
    I'm always a little hesitant about approaching people directly about this sort of stuff - my knowledge of the subject is limited (to say the least!) and I hate appearing to be a complete goose - probably as much as they dislike being pestered by them!:D
    But I'll drop him a note - and just say you sent me!!:D :D
     
    Willallison, Jul 30, 2002
    #8
  9. Willallison
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    Willallison Senior Member

    Jeff,
    I contacted Trevor as you suggested. He was straight back to me and very helpful - thanks for the tip
     
    Willallison, Jul 31, 2002
    #9
  10. Evolution Yacht
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    Evolution Yacht Junior Member

    Sorry I am so late to this thread, but Dave Gerr's book boat strength has a lot of info on how to calculate prelim scantlings and weight calcs.
    SG
     
    Evolution Yacht, Sep 9, 2002
    #10
  11. JEM
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    JEM Senior Member

    I've heard from 2 designers the Dave Gerr's book has some short comings. What are they? Is it true? I don't have enough knowledge to express an opinion about it.
     
    JEM, Jul 27, 2004
    #11
  12. sorenfdk
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    sorenfdk Yacht Designer

    I think Dave Gerr's book is quite good, but not if you're into building very light.
     
    sorenfdk, Jul 27, 2004
    #12
  13. mistral
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    mistral Senior Member

    come on Soren ,don't be shy ;) , give us some good suggestions about related books on this topic, we'll greatly appreciate them

    mistral
     
    mistral, Jul 27, 2004
    #13
  14. sorenfdk
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    sorenfdk Yacht Designer

    If I knew about any books about building lightweight boats, I would be happy to tell you about them, but unfortunately I don't...

    If anybody does, please don't hesitate to tell us about them!
     
    sorenfdk, Jul 27, 2004
    #14

  16. TheFisher
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    TheFisher Junior Member

    Personally, I'd accept a modest weight penalty for the benefits of additional strength.

    The sea is an unforgiving mistress :)
     
    Last edited: Jul 27, 2004
    TheFisher, Jul 27, 2004
    #15
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