Skin-on-frame canoe/kayak plan help

Discussion in 'Boat Design' started by Ruming Jiang, Mar 8, 2021.

  1. Ruming Jiang
    Joined: Mar 2021
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    Ruming Jiang Junior Member

    I'm looking to build a canoe and a kayak with skin-on-frame structure. They are both meant for recreational flatwater paddling so performance is not the priority.

    The challenge is the material I want to use for the skin is flat sheet and non-elastic, thus can't be stretched to fit the contour of a regular plan. Although I can always cut and stitch/glue somewhere in the middle, it is not ideal due to additional complexity and risk. Cutting off excess material is okay. Thus I'll need a plan that fits the properties of the material, instead of the other way around.

    What's the best way to get such a design done? I don't have any boat design experience but okay to learn new software if the learning curve is not too steep. That being said I guess it could be easy for an experienced designer. I'd appreciate if someone, ideally also a paddling enthusiast, is willing to help. Please reply or PM. Thanks
     
  2. bajansailor
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    bajansailor Marine Surveyor

    Welcome to the Forum RJ.

    What is the flat sheet / non-elastic material that you want to use for the skin?
    It sounds like you will need to have a design with a chined hull, rather than 'round bilge' - ie in similar fashion to so many of the plywood chined boats out there.

    If you want 'skin on frame', then you really need to use a skin that can be stretched to suit surely?
    I presume that you have come across the Geodesic Aerolite designs?
    Geodesic AiroLITE Boats - ultra lightweight SOF canoes and boats; plans, projects and tutorials https://www.gaboats.com/
     
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  3. gonzo
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    gonzo Senior Member

    Why did you choose that material? Skin on frame requires a material that is just about the opposite of what you describe. Software is not going to give you a solution, only a drawing. Designing a boat means to develop a structure that fits the intended use and purpose. The drawing is only a representation of the design. There are plenty of designs for skin and frame, including all the historical traditional ones.
     
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  4. Ruming Jiang
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    Ruming Jiang Junior Member

    Yes, I looked into Airolite. That's the one inspired me to go with skin on frame. I just want to use different materials to make it portable(portageable) just like camping tents.

    The skin is going to be thick PE film, possibly vinyl, or multi-layer with nylon reinforced. I'll need to find something balanced with anti-puncture, availability, cost and manufacturability.

    I have zero knowledge in hull design. Does a chined hull have different performance from round bilge?

    Thanks
     
  5. bajansailor
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    bajansailor Marine Surveyor

    Sorry, I was thinking that you would be using a skin that can only bend one way (like thin plywood), ie not have compound curvature.
    But it sounds like your thick PE film should be able to have some compound curvature? If so, then a round bilge hull should be viable?
    A round bilge hull should in theory have slightly less resistance than a chined hull, if you compare two hulls with the same dimensions and displacement.

    However, if your heart is set on skin on frames, there are probably good reasons why folk like Platt Monfort (of Geodesic boats fame - I met him once, in Rockland, Maine, summer 1995 - he was a true gentleman) and others do not use vinyl materials like what you propose - I am sure that they found out the hard way as to what works, and what does not.
     
  6. gonzo
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    gonzo Senior Member

    It depends there are too many variables to make generic statements. Make yourself a favor and buy a design and follow the instructions and uses the materials specified by the designer.
     
  7. Ruming Jiang
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    Ruming Jiang Junior Member

    Here are my priorities:

    1. Use and purpose: recreational paddling, camping, flatwater or class 1
    2. Portability, take down, light weight
    3. Simplicity, easy to make, easy to use
    4. Material, availability and cost
     
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  8. Ruming Jiang
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    Ruming Jiang Junior Member

    I used to build wooden skin-on-frame model airplanes at school age. My mentor builds indoor models as light as 1gram, with skin on frame structure. There is definitely beauty in it. However, from what I learned in model aviation, it is the new material and technolgy that makes the whole industry fly, and makes them accessible to a broader population, instead of a few hobbiests.

    Chined hull might be less desirable, as the film at the chines would be more susceptible to scratch and impact, which reduces reliability.

    If round bilge hull is viable, what are the conditions it should meet to "fit" such skin? It's going beyond highschool geometry.
     
  9. Ruming Jiang
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    Ruming Jiang Junior Member

    It doesn't help with the problem I want to solve but thanks for the suggestion though.
     
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  10. bajansailor
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    bajansailor Marine Surveyor

    Thinking about it, even thin film is not going to wrap perfectly around a soccer ball - this must be the ultimate example of compound curvature!
    You would have overlaps, and have make cuts in the film, to allow it to lay nicely - and I suppose the same principle apply for the skin of a round bilge boat.

    Gonzo makes a good point about buying a proven design for this building technique.
    But you do not appear to be too keen on the Aerolite designs - what do you not like about them?
     
  11. Ruming Jiang
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    Ruming Jiang Junior Member

    Nothing I do not like. They are beautiful designs, just do not solve the problem I focus, in 2 ways:

    1. Too much effort, plus tools and skills required to build, thus costly.
    2. Takes place in storage and difficult to transport.
     
  12. Rumars
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    Rumars Senior Member

  13. Tiny Turnip
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    Tiny Turnip Senior Member

    For incisive support, it would help if you can further clarify some of your requirements. The Geodesic Aerolite boats are the lightest you will find, albeit, as you say, with some complexity of build. It sounds as if you want a boat that folds or breaks down. Is that correct?
    If so, there are numbers of foldable canoe and kayak plans.
    You mention PE; I understand PE to be heat formable, and thus should work for compound curvatures. However, I doubt that it will take sharp or repeated folding, as may be necessary for a foldable boat for very long. DIY Foldable boats tend to use canvas. Commercial foldable boats tend to use polypropylene, which should be better for repeated folding than PE
    It is easy to find inspiration: Best Folding Kayaks Reviewed For 2021 | How To Choose & Build (Oru) https://kayakguru.com/best-folding-kayak/
     
  14. upchurchmr
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    upchurchmr Senior Member

    Yost suggestion is a good one, since he had a takedown design.
    Takedown is going to be the most severe requirement for finding an existing design.

    Vinyl has been used a lot in older designs but I don't know about takedown - or I have forgotten.

    Good luck.

    There is another guy (forget his name right now) who sells kayak skin materials who has a takedown design or two. I'll try to rack my tired brain.
     

  15. Ruming Jiang
    Joined: Mar 2021
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    Location: Vancouver BC Canada

    Ruming Jiang Junior Member

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