Anyone know of plans for a CNC boat kit that is riveted NOT welded together?

Discussion in 'Boat Design' started by wannarivet, Apr 1, 2018.

  1. gonzo
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    gonzo Senior Member

    That is completely incorrect. Fiberglass boatbuilders do not have an angle carbon fiber piece added to transom, etc. The hull is laminated as a single unit; often with the reinforcements included. You are also wrong in that boat builders don't want to sell you data or don't understand what you want to do. It is simply that your idea is very flawed.
     
  2. valery gaulin
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    valery gaulin Senior Member

    Wannarivet, just buy a plywood epoxy boat plan and go ahead with your built. There is so many good design for wood epoxy construction up to pretty much any size! In my opinion wood epoxy (cold molded construction) is the best method for the DIY one off boat. Next method would be welded steel construction after in 3rd place welded aluminum construction.

    There is other method but usually not good for one off construction for the DIY in my opinion.
     
  3. wannarivet
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    wannarivet New Member

    Sigh... Arggg... OK, I'm not articulating myself nor using the proper marine terms and I think that that's where the disconnect is. So, let me try again.
    Start by imagining these 3 ways to build a boat: fiberglass hand lay up, flat sheet cut on a CNC machine and welded (metal boat kits) and riveted from either flat or prebent material. Why can't a builder take the advantages of each method and combine them?

    Remember, that I used to work in aerospace so I'm a big believer in composite materials.

    Let's start with the easy stuff. I called them crossmembers and transom. Mistake, I meant stringers and the bulkheads. For me, the bulkhead is the thing at the back of the fuselage that separates the pressurized cabin from the non pressurized parts of the plane. AFAIK boats made in the 70s and 80s used plywood stringers and bulkheads in a fiberglass hull. Correct me if I'm wrong, but I don't believe that any boat builder screwed the bulkheads and stringers through the hull into the wood. No, they were glassed in. So, if a boat can be built using glassed in plywood stringers and bulkheads, then why can't a boat be made with glassed in stringers and bulkheads made from composite sandwich materials? Furthermore, instead of using fiberglass to glass in the bulkheads, I'd use carbon fiber which would make for a stronger joint. No? This is what I meant by the term carbon fiber angles.

    I don't see this idea as flawed, sorry.

    Now for the hull. Think metal boat kits. Instead of using aluminum sheets cut out to make the stringers, bulkheads and hull all cut out from aluminum or steel flat sheet on a CNC machine, why can't you put a composite sandwich panel in the CNC machine instead? You get exactly the same parts but with material that is 1/3 the weight and maybe double the cost. Less if you use fiberglass twill instead of carbon fiber twill. The problem is how to join them all? That's why I posted to the forum... Welding won't work but riveting would (the titanic was riveted), which was my original idea. Now imagine all those the parts joined together by what boat builders call glassed in. I already know that boats where glassed in with plywood and they worked fine. Correct me if I'm wrong, but I've never heard of a glassed in bulkhead or stringer breaking free of the glassed in part. Instead, the wood tends to rot.

    So, I hope that I've distilled my boat building idea into something that makes more sense.

    Rob
     
  4. gonzo
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    gonzo Senior Member

    Firstly, the Titanic sunk; not a good example. Secondly, if you were in aerospace, would you mix the building methods of a hot air balloon and a 757?
     
  5. chinaseapirate

    chinaseapirate Previous Member

    All right, you have distilled a completely new design. From riveted aluminum to composite aircraft cabins "glassed" together. Correct? What is the problem that your asking then? How to find plans? Use Valery's suggestion. Look at plywood plans, and go ahead with YOUR build. Just make sure they are built over a frame and don't call for stressing the hull panels into shape and then fitting the bulkheads to the hull. Your panels won't conform. The aluminum kit plans should work also, probably better because the designs are engineered with the skin carrying a larger % of the hull strength similar to what your composite panels would certainly be capable of. Absolutely do not rivet aircraft cabin interior together...
    You are also going to have to route/chisel/saw/poke/whatever out the core in all edges of the panel (where you can't glass both sides of the joint) to a depth greater than the thickness of your your panel and fill all of them back in with a high density filler such as epoxy+chopped fiberglass. And if your core is just novalac coated paper don't dent or crack the hull (lol). You won't find many you tube videos on your construction method either.
     
  6. Angélique
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    Angélique aka Angel (only by name)

    There's some English boat terminology on the thread:

    Beginners Guide To Boating Stuff ! ---> Page 13 ---> post #185 - to - #189 - & - post #192 - + - post #193

    Note: the easiest way to go to all the linked English boating terms there would be just to scroll down the page #13 link.

    Good luck !
     
    Last edited: Apr 4, 2018
  7. Rumars
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    Rumars Senior Member

    I guess it's really hard to describe flat panel composite construction.
    What kind of boat do you want? Sail, power, oar? Mono or multihull? Plywood, balsa cored (Duflex, DuraKore), foam cored? Do you want to make the panels yourself or buy them?
     
  8. Angélique
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    Angélique aka Angel (only by name)

    Forum member Richard Woods offers the option of GRP flat panel hull construction on some of his Cat designs, like eg Surfsong, a 8.3m deep V hull sail cruiser.

    Surfsong ‘‘ 8.3 m Deep V Cruiser - sheet ply or grp flat panel hulls, ply decks ’’

    See also Richard's article: Flat Panel Construction

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    P.S. - Saw also the option of GRP flat panel hull construction on the Woods sailing Cats:

    Windsong ‘‘ 9 m deep V hull ocean cruiser - sheet ply or grp flat panel deep V shaped hulls, ply decks ’’

    Mira ‘‘ 10.65 m deep V hull open deck ocean cruiser - sheet ply or grp flat panel deep V hulls, or strip plank round bilge hulls ’’
     
    Last edited: Apr 4, 2018
  9. wannarivet
    Joined: Apr 2018
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    wannarivet New Member

    Special thanks to Valerie and Angelique, who really nailed what I was looking for. As a bonus, someone actually sent me the study plans for a 27 foot boat for free. He didn't say specifically, but he's very interested in my project because he gets a lot of people who can't weld. The appeal of hand layup is enormous.

    Thanks again for everyone's comments.
     
  10. M&M Ovenden
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    M&M Ovenden Senior Member

    Rob,
    What sort of boat and size are you looking for ? If you want to work in sheet material aluminum or steel has some favorable properties over composite panels for boat building. Most panel friendly boat shapes use developable surfaces to get some very fair lines. I feel the composite sheets will be far to rigid in this application and don't offer any advantage. You can learn to weld easily.

    Cheers,
    Mark
     
  11. Zulu40
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    Zulu40 Junior Member

    thats the case. When shipbuilding shifted from riveted to weldment structures as in liberty ships, the skill requirements where found to be less, and speed of construction faster
     
  12. Zulu40
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    Zulu40 Junior Member

    Good analysis of both existing and previous designs concludes that aircraft designed to be on the water such as flying boats are 1.25x heavier than conventional aircraft they replace. Boat amphibians are even heavier at 1.3x
    (The Design of the Aeroplane, Stinton D., pp522)
     
  13. Zulu40
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    Zulu40 Junior Member

    Im not totally distressed at the idea, because on occasion we move forward a little in reviewing older methods.
    But I have some things for you to consider

    I dont think the aircraft / boat analogy holds up, they are quite different structures for different mediums
    Places of discovery to go to are flying boats, amphibious aircraft, seaplanes, ground effect machines.
    I hope your Russian is good, but Im assuming nyet

    Supposing that doesnt deter you, if you havent noticed aircraft have been moving to adhesives for some time
    and boats too have been using adhesives in the aluminium sphere
    Since a riveted aluminium hull will need sealants anyway, why not shift the idea to adhesives?

    Удачи и наилучшие пожелания
     
  14. Angélique
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    Angélique aka Angel (only by name)

    Hi Zulu,

    Do these adhesives call for a controlled environment during application and curing ?

    If so, what are the requirements ?
     

  15. Zulu40
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    Zulu40 Junior Member

    PC 11, but its an old adhesive by now
    or West Systems G-Flex, but quite expensive

    I would think the surface prep would need to be meticulous clean and properly mating surfaces
    it possibly involves acid etching, but check with West Systems, they can inform you

    but you would want similar surface prep (sans the clean) for riveting anyway
    and it is all done by hand
     
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