Another way to design & build in Aluminium boats

Discussion in 'Metal Boat Building' started by monomad, May 17, 2014.

  1. monomad
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    monomad Junior Member

    Hi I have been designing and building aluminium boats in Australia for some years , so I thought I would show you one of my boats.
    The photo shows how I build the boat up side down then I turn it over then the sides, transom
    and bow go on.
     

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  2. Mr Efficiency
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    Mr Efficiency Senior Member

    G'day mate, looks like a pretty steep vee, about 22* ? And you have a self-drain floor by the looks of it ?
     
  3. Ad Hoc
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    Ad Hoc Naval Architect

    Looks good. But those long.ts are veryyyyyyyyyyy heavy!
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    You can tell the gauge from the picture ? :D
     
  5. daiquiri
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    daiquiri Engineering and Design

    I think AH was not referring to the gauge but to the height (or molding) of the longitudinals. They indeed look oversized, at least at first glance. Since they appear to be CNC-cut, lightening holes could have been included in the design, IMO. However, the designer will certainly know better why did he choose do it that way.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    They are going to support the sole, which looks about the right height to be self-draining, no ? Possibly checkerplate. And maybe create some bouyancy chambers at the same time.
     
  7. TANSL
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    TANSL Senior Member

    All parts, both longitudinal and transverse should lighten.
    Apparently you had to chamfer the top edges (low in their true position) of each piece, which is a huge job that can be easily avoided just by following good practice of metal structures loftman.
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    I'll have to get new glasses, I can't see all this detail. But to be deemed too heavy, you'd have to know the material thickness, surely ?
     
  9. TANSL
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    TANSL Senior Member

    I do not want to be disrespectful but it is obvious that in addition to glasses, you must have some knowledge and experience. Why do you want to know the thickness of the material?. Yes, there I have to admit that I do not understand you.
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    haha, if it is 6mm, it(the framing) will be twice as heavy as 3mm, simples ! How else can you make a judgement of how heavy it is ? Maybe you assume he is following some standard that applies to such construction, but I don't know if he is.
     
  11. daiquiri
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    daiquiri Engineering and Design

    Not really so, Mr.E. :)
    It is pretty obvious, if one knows how the stress is transmitted through structures, that there are large portions of those reinforcements which won't give any useful contribution to the structural resistance. Those portions are just adding an easily avoidable weight.
    The buoyancy chambers might make sense though. That's why I said that the designer of the boat (Monomad?) is probably the only one who knows why that hull is made the way it is made.

    Cheers
     
  12. Ad Hoc
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    Ad Hoc Naval Architect

    Indeed :D

    There are also no mouse holes I can see anywhere...which is a worry too.:(
     
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    So, the framing elements are too deep, and he'd have been better to have more of them, more closely spaced, but not with that depth ? I suppose a lot depends on the plate thickness he has selected for the bottom of the boat. He might be going greater than normal, in fact judging by the rise in the bottom of that boat, it better be beefy, or the thing will not float on its waterline, to my eye it looks to be around 22 degrees, which is a lot more than most comparable alloy boats. In addition, he might have some aggressive external strakes planned for the bottom, which will have a structural contribution. In any case, it is not too late to employ a large holesaw to alter those framing panels. :)
     
  14. monomad
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    monomad Junior Member

    Hi longitudinals ( girders )are 3mm and the deepest ones are 405mm.
    Cutting holes in them would not save much in weight because you would then have to add more transverses ( ribs ) to stop the girders from twisting.
    I don't cut so called mouse holes in my ribs until they are fitted, this way it makes it easy to line them up with the top of my girders which are bevel at the top with a belt sander.
    This fabrication method that you see in this boat I have been using since the late 1980 and the boats that I designed and built back then are still operating.
    If one is going to add some extra strength ( weight ) in a boat,under the floor is where you want it.
    No CNC cutting is used in my boats as they are custom built for each customer.
     

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  15. TANSL
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    TANSL Senior Member

    Hello monomad, first, I have to acknowledge the great work done, as what I can see in the pictures.
    I have extensive experience in designing and building metal boats and I can assure you with a detailed study of the structure, it could get lower weight and labor for it.
    I have intervened in the construction of large number of vessels, of which only one unit is built, and I always cut CNC parts because it was the cheapest method.
    I can send you examples of what I've done and give, at no cost to you, a test with any of your projects.
    You send me an e.mail, if interested.
     
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