One off fiberglass non mold resources

Discussion in 'Fiberglass and Composite Boat Building' started by John Rivers, Oct 9, 2022.

  1. John Rivers
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    John Rivers Junior Member

    I would like to build a one off fiberglass without mold that has complex concaves. Can anyone provide a resource for the most modern comprehensive review of how to go about complex concaves on a non mold fiberglass hull? Thanks so much. I am having a difficult time finding resources on it.
     
  2. bajansailor
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    bajansailor Marine Surveyor

    Re how you want to build this boat without a mould, do you mean the usual female mould, where you build the boat inside the mould, or are you also excluding a male mould, where you essentially build the hull on the outside of the mould?

    With a male mould, this can be very basic (compared to a female mould), to form the shape for eg foam sandwich construction.

    Do you have any drawings or sketches that you can post of the one off vessel with complex concaves that you would like to build?
    If so, can you post them on here please?
     
  3. wet feet
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    wet feet Senior Member

    It isn't often described because it is a lot more difficult than working with a finished female mould.In fact ,I know of one company that refuses to undertake such work and they require a male component to undertake work on.The more modern approach is to CNC machine a female mould and it can work wonderfully if you have a clean and well faired CAD model.Not too many of us have a 5 axis CNC machine on tap and it isn't exactly a budget option to have the work done.For a small component it is possible to have the female tooling made in sections of a thickness to fit on a much less exotic 3 axis CNC machine and to glue a stack of them together-then paint the surface.
     
  4. John Rivers
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    John Rivers Junior Member

    I can post sketches but I am building it in solidworks and have to know how to place the design for the skeleton for the hull.

    There are discussions on one off fiberglass without molds, but not a lot of details. Such as how to layup the first skin for concaves. As well as what to do about fill and first skin for the inside. I want to make sure the techniques are up to date.

    My center hull is something like thunderchild 2 and my amas look similar to this. But extra steppings of concaves. I have a couple designs but am going to run them on a simulator software at the college before I choose a final design.
     

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  5. John Rivers
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    John Rivers Junior Member

    The amas will be asymmetric. So no point in making a mold for them. These are going to be small prototypes before I settle on a double or 3:2 scale of the design.
     
  6. jehardiman
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    jehardiman Senior Member

    What you're probably thinking about is C-Flex.
    C-Flex https://www.seemanncomposites.com/cflex/
    There is link on the page for a downloadable manual.
    You are still going to need a set of forms, but much of that can be incorporated into the finished structure.
     
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  7. bajansailor
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    bajansailor Marine Surveyor

    I presume you mean the vessel built by Safehaven Marine?
    https://www.safehavenmarine.com/xsv20

    Are you planning on building a trimaran, with a centre hull like Thunderchild 2?
    How big will this trimaran be?

    Re 'extra steppings of concaves', is this for all three hulls, or just the amas?
     
  8. John Rivers
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    John Rivers Junior Member

    All the hulls will have complex shapes that the 1st outside layer will need to attach to a frame. I don't see how applying foam as the first layer will be structurally sound. I'm also exploring 3d printing the hull skeleton and am wondering what fastenings or gluing methods are used.
     
  9. John Rivers
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    John Rivers Junior Member

    Eventually I want it to be 30-36' foot. The center hull will be thin like the amas and the rear of the hull is modified for trimaran characteristics. It's a reverse bow with concave catches down the hull like thunderchild 2 but not as wide.

    I'm also exploring possible concepts for frame reinforcement using tensegrity and am curious about the exterior fastening system of the first layer.
     
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  10. John Rivers
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    John Rivers Junior Member

    Boom! Yessir!
     
  11. jehardiman
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    jehardiman Senior Member

    Oh, so you mean standard construction methods used since Brunel started the Clifton Suspension Bridge in 1831 ....<rolleyes>
     
  12. John Rivers
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    John Rivers Junior Member

    Are there uses of tensigrity in structures other than bridges and mast cables?

    I'm wondering if arms can be strengthened and possibly lightened using tensigrity stitching down the arm. Another use would be in lightening structural support but it fills the space with cabling and rods.
    Don't know. Haven't seen anything like that.
    Another idea I am wondering about is using carbon fiber yarn in a sparse netting crotchet or wrapping geometry.
     
  13. John Rivers
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    John Rivers Junior Member

    I was thinking of getting the vertical body frames of plywood and to get aluminum sheet water jetted and either as a flange to the plywood or sandwich between two layers of plywood at every frame slice. This way I can use 2x4s for bracing instead of wasting sheets of plywood, as am more likely and easily able to reuse cut 2x4s. Whereas the plywood would probably go in the trash. If I only get a say 3inch flange cut for the body shape at each vertical. That wouldn't be super expensive. I have a plasma cutter but I can easily send an stl file to the waterjet cutter. I could feel safe about storing lots of batteries on those frames. It would also give me a perfect template with perfect measuring markers I can have etched on.
    Mmmmmm. And pushing on the frame to ensure the correct fastening for extreme curves I definitely want a super supported frame.
     
  14. jehardiman
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    jehardiman Senior Member

    I take it you've never heard of the 1930 J boat Enterprise or the late 1970's Imp?
    http://www.america-scoop.com/documents/05/05299.jpg
    RB Sailing: Imp (Holland 40) http://rbsailing.blogspot.com/2013/09/imp-holland-40.html

    You really need to read up on structures and how/why they are selected for function. FWIW, for a member always in tension, having a beam rather than a cable or tie rod can be a blessing as anyone who has had to access around straight line members can attest.
     
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  15. John Rivers
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    John Rivers Junior Member

    Cool! Thanks! I haven't studied alot about boat history or boats persay and it's difficult to find those types of things from Google engines. Looking for ideas that related to tensegrity for artificial reefs and articial Islands.

    I have a pretty good understanding of hydrodynamics at play for specific function. I have a specific set function in mind, weight,displacement, etc. I'm going to build my first project small but am going to do Sims on it before I have a final build in solidworks. I have studied theoretical physics for about 13 years so I have a background in understand engineering theory and do my research in those regards. I also don't mind saying I don't have alot of k owledge in boat building but have studied the design of boats for some time. I know there is essentially no perfect design but things can be modified. If a reverse bow digs a tiny too much in design I can tweak it just just bit, or just let off the sails or reef the main in extremely windy or extremely large swell conditions. I'm not going to just build a boat "willy nilly". I'm doing my research. Which is why it's important for me to know what the first layer is so I can design the support frame. If they just stapled plastic to the frame as the first layer, that would change my support strategy.
     
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