About building a frp sloop by the 3D printer

Discussion in 'Boat Design' started by Steve.Y, Nov 16, 2019.

  1. Steve.Y
    Joined: Nov 2019
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    Location: South Korea

    Steve.Y New Member

    Hello, Masters!
    Actually, I'm a very newbie in this area so don't blame that my ridiculous question.
    The question is that the polycarbonate can be the matrix of frp stacking structure or not.
    Most of other plastics for the 3D printer are denaturated under 100 celsius degree but PC can stand over 140 celsius degree. So I wonder that PC can be matrix to stack the frp structure.
    By my rough calculating, 100ft*20ft*13ft hull needs about 7,000kg of PC and It will cost 13.5$/kg * 7000kg from china(except shipping charge and taxes) .
    And by using 4 modix 120x(1200mm*610mm*610mm) it will take about 3~4 month to print out all panels for a 100ft sloop.

    My 'blue print' is like following drawing. (Sorry for very low quality)

    --------------------------------- Aramid fiber with epoxy
    --------------------------------- Glass fiber with epoxy
    --------------------------------- Glass fiber with epoxy
    --------------------------------- Glass fiber with epoxy
    --------------------------------- Polyurethane foam
    --------------------------------- Polycarbonate matrix
    --------------------------------- Polyurethane foam
    --------------------------------- Glass fiber with epoxy
    --------------------------------- Glass fiber with epoxy
    --------------------------------- Glass fiber with epoxy
    --------------------------------- Aramid fiber with epoxy

    If this structure looks like not impossible to real professionals, I will go to the master's degree to make it happen.
    Because 100ft sloop is very very expensive for me, So i wanna build my boat on my own under 500,000$.
    Tell me your advice please, I'm really waiting for that.
    Thank you for reading it. :)
  2. gonzo
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    gonzo Senior Member

    The deck of the boat will weigh more than what you are calculating. Further, to build a printer of the size necessary will cost more than $500,000. You need to build a whole structure and not a series of small pieces. To that cost you need to add all the structural interior, ballast, rig, sails, engine, electrical systems, plumbing, etc. You could go to a third world country and have a boat built for the budget with local materials. It will be rough but serviceable. However, those boats require a lot of maintenance, which is only realistic in countries where labor is very cheap.
  3. rnlock
    Joined: Aug 2016
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    rnlock Senior Member

    Steve Y:

    What's the purpose of the polycarbonate in the middle of the layup? Seems like foam ought to be enough there. Why do you need 140 C? What part of the boat is going to be hotter than that, this side of a fire? Boats made with, say, WEST epoxy are going to start to have problems maybe around 140 F, not 140 C. That's one reason why a lot of decks are white.

    You might consider a thin layer of fiberglass/epoxy on the outside. I understand that aramid fiber can be really hard to sand to a good finish, so repairs or refinishing might be a big problem.

    Can you do 3d printing with long fibers? If not, the structural properties will be inferior, I think, and you'll have to use much more material. If you can keep the long fibers straight, you might get away with less material than a conventional FRP boat uses. Scrap iron in concrete is a traditional inexpensive way to make ballast, but it will require much more room than lead.

    I'm sure the boat can be built in modules if properly engineered. It might weigh a bit more. I'm assuming you mean 12,000 millimeters, not the 1,200 you wrote. 12 X 6 X 6 meters is pretty big, IMHO. As you say, only 4 pieces required. If you meant 1,200 mm, that would mean hundreds of pieces! Might as well build the boat by hand at that point.

    I suspect gonzo is correct that all the other items will add up to much more than the hull itself. I suppose if you make the boat VERY basic, you can get reduce that to some extent. If you can do long, straight fibers, and use carbon fiber, I guess you could make a freestanding carbon/epoxy mast. That ought to be much cheaper than a custom aluminum mast with all the fittings. If you don't need an auxiliary engine that would save another big chunk of money. If you did, and you didn't mind going slowly, I suppose you could use a small engine swinging a large prop. The large prop would be bad for sailing performance, though. Seems to me the first and best route to economizing is to reconsider if you really need a boat that big. Or perhaps I should say a ship.

    Maybe you can finance your huge 3D printer by building houses with it! I know people have been working on this application for some time now.

    Keep in mind that I'm not a professional naval architect, though I have an engineering background. Also, so far I've only designed one small boat, which worked out fine except for the time required to build.
    bajansailor likes this.
  4. bhnautika
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    bhnautika Senior Member

    SteveY watch this
  5. Dejay
    Joined: Mar 2018
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    Dejay Senior Newbie

    Hi Steve Y, I've wondered about such things too. I'm not an expert, but some rather "crazy" thoughts and ideas:

    1. Probably the most efficient way to build an efficient hull is to have a large mold, lay out all your cloth and core material and vacuum infuse. This saves a ton of surface prep. But you need a mold of course. In the ideal case 3D printing could save time and money, but it probably will be heavier because less optimized.

    2. You could 3D print a mold. I believe this is already done. But you then still need to mill the 3D printed pieces. Lots of surface prep and cost.

    3. 3D printing in that 1.2m printer could maybe print lots and lots of panels that replace your core material. Instead of flat panels you could print curved panels that fit together and use optimized hexagonal shapes for high stiffness. But I believe you can't vacuum such panels. Maybe you could "fill" those 3D printed pieces with PU foam before infusion... But ultimately this only saves you bending and cutting the foam to the right size. Structural foam like PVC or others (not PU!) is rather expensive but I doubt you'll save much with this 3D printing approach.

    4. Theoretically 3D printed core could reduce the amount of fiberglass you need because you could have thicker surface layers. You get enough tensile strength from relatively little fiberglass already (400gsm? not sure for a 100ft sloop, that is big) but you need more fiberglass on foam to get enough impact resistance. That is the advantage of balsa core, better impact strength. A 3D printed and suitably structurally optimized infill for the panels could give you better. But again, vacuum infusion is not an option with the "open cell" nature of 3D prints.

    Check out this thread if you haven't already: 3d printing technology in boat building ? https://www.boatdesign.net/threads/3d-printing-technology-in-boat-building.60736/page-3#post-862905

    I'd also check out the intelligent infusion which is simply a smart way to design the boat with easily buildable molds in mind or have most of it infused on tables with foldable things and planning ahead with how to cut the foam before infusion.

    So ultimately I think you save the most money with a good design and easy to build molds for "intelligent infusion". Also, and this is just personal opinion, don't build a sloop, build a multihull ;)
  6. Dejay
    Joined: Mar 2018
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    Dejay Senior Newbie

    PS: Thomas Sanladerer has a video about "Anisoprint" which can embed continuous fiber into different plastics. I think the fiber is impregnated with a thermoset plastic that bonds to different plastics.

    But the problem with this is that you'd need to print the actual surface, so you'd need an actual 100ft 3D printer. And I don't think you ever get the same fiber to matrix ratio as with vacuum infusion. It won't be as strong.

    But maybe you used the word "matrix" wrong. Maybe you mean core?

    Also as mentioned, PU foam isn't a structural foam for a boat hull.
  7. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    Steve Y. are you really so clueless about boats? Your ideea can be done but it makes no sense structurally, economically or work time wise. A sandwich carries the forces in the skins, a tough heavy material in the middle is nonsense. A core needs shear strenght, a composite core of foam/PC/foam needs a foam to PC bond that exceeds the foams sheer strenght. So now you pay 100 000$ for a material that is heavy and does nothing but provide a shape to epoxy glue foam on. Since this is a positive form you save nothing in fairing the finished product.

    Building a 100' boat for 500 000$ is totally doable. I can say that with confidence because "100' sloop" is about as specific as "black car". The hull and deck portion of a boatbuild are just 15-30% of the work and cost anyway.

  8. rnlock
    Joined: Aug 2016
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    rnlock Senior Member

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