Planking a ply on frame design with solid wood?

Discussion in 'Materials' started by Heimfried, Jan 4, 2020.

  1. Rumars
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    Rumars Senior Member

    Because he probably lives in an apartment on the x'th floor where getting a full size sheet of ply in requires an outside lift to the window like anything that is bigger than 2x1m and does not bend around corners. Building probably happens in a summer garden in the city outskirts on a dirt floor.
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    And yet is able to assemble a "tent" on the grounds of this multi-storey building ? Might as well put another tent up with the ply in that.
     
  3. Mio
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    Mio New Member

    Morning,

    first of all, thank you very much for the warm welcom and the constructive answers.

    @fallguy :
    The approach you suggested was the one I had planned, so if epoxy, then like this.

    @Rumars @gonzo :
    Double planking is certainly a good idea and cutting the wood would not be a problem. For the logs, I would also want to use fir, the purchase could also be in the small quantities needed and to be processed.
    But I don't think that double planking is necessary for the structural integrity of the boat (o.k., the bottom may be a bit stronger).
    Or do you think that this procedure would be necessary because of the swelling G√ľnter feared?

    @bajansailor :
    Yes, the dimensions are so strong. The boat will be able to navigate the Northwest Passage even in winter :cool:.
    Caulking is unfortunately out of the question, as the boat will be standing on the trailer most of the time and will be used during holidays and on some weekends.
    And one picture:
    [​IMG]

    Thanks again for the friendly help so far.

    Mio

    @Mr Efficiency :
    It would be more efficient if you wouldn't judge me without knowing me and my circumstances. Thank you, Mr Efficiency.
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    No worries, but it sounds like you are making unnecessary work for yourself. :)
     
  5. Heimfried
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    Heimfried Senior Member

    Mio's build is a hard chine flat bottom design. So cold moulding will not be possible.
     
  6. DCockey
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    DCockey Senior Member

    Cold molding of the sides and cold molding of the bottom is absolutely possible. It is not possible to cold mold continuously from keel to sheer. There needs to be chine log.
     
  7. TeddyDiver
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    TeddyDiver Gollywobbler

    Anything can be cold moulded, I made the cockpit sole and the bridge deck cold molded and they are allmost flat, a of bit chamber but not much. It's all about framing..
    Mio, look up strip planking methods with epoxy and glass fiber skins like some post earlier suggested. "Gougeon brothers on boatbuilding" is free online, read it!

    ps the link: Gougeon Brothers on Boat Construction book - WEST SYSTEM Epoxy https://www.westsystem.com/the-gougeon-brothers-on-boat-construction/
     
    Last edited: Jan 5, 2020
  8. fallguy
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    fallguy Senior Member

    It should be noted that epoxy is not very suited for uv exposure. So if you take a long time to finish planking; you run the risk of the neat coat chalking and flaking. You will need to cover the boat with a tarp to protect the epoxy if you expect it to take more than say 6 months
     
  9. gonzo
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    gonzo Senior Member

    Fir checks a lot. It is not a good species of wood for thin planking.
     
  10. bajansailor
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    bajansailor Marine Surveyor

    Mio, re the sketch above, it looks very familiar but I cannot put a name to it - perhaps just as well!

    Do the plans also show how to adapt the transom for an outboard motor instead?
    The transom angle appears to be too steep / raked for an outboard engine, unless there is a well in the middle with less rake.

    You mention that you will fit the boat with a 6 hp O/B motor - this will be much less efficient at propelling a heavy boat than a 7 hp inboard diesel engine.
    Will you be keeping the keel / skeg as shown in the drawing?
    Could you maybe post a photo of what you have built so far please?

    I think you mentioned that you have all the frames set up already - are they really spaced only 10" apart?
    The station spacing on the drawing appears to be 1'8" (ie 20") which seems to be more reasonable.

    Your design appear to be similar in some ways to Sam Devlin's 16' Godzilli -
    Godzilli 16 https://devlinboat.com/godzilli-16/
    Note that she has a 20 hp high thrust O/B motor.
     
    Last edited: Jan 5, 2020
  11. Heimfried
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    Heimfried Senior Member

    Sorry, that statement was apparently a proof of my limited knowledge. Until now I saw cold moulding only at round bilge boats.
     
  12. bajansailor
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    bajansailor Marine Surveyor

  13. gonzo
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    gonzo Senior Member

    That looks like a redwing. If you plank it, the framing or the skins will have to be redesigned. It would be less of a hassle to wrap the plywood in plastic and store next to the tent.
     
  14. fallguy
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    fallguy Senior Member

    Pay close attention to this statement. Changing the hull planking, weight, scantlings is not always so simple. And you don't want your hull weight to change a lot or you will start to deepen the waterline and impact performance and loading permitted.
     

  15. Tad
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    Tad Boat Designer

    It's my Alder design. This hull is not weight sensitive at all.

    I would not recommend trying to sheath the inside of a solid framed boat, a painful process that's unlikely to turn out perfect.

    In planking this boat in solid timber for life on a trailer I would double-plank both the bottom and topsides. Two layers of 1/2" on the bottom and two layers of 3/8" on the topsides. The seams of the outer layer land in the middle of the inner planks. I would highly recommend red cedar or mahogany for planking. Using these thin layers of wood minimizes movement. Seal all planking with S-1 sealer and fit seams tight. Then you could sheath the outside with Dynel or Vectran for abrasion resistance.

    If you fit an additional flat mid-stringer in the bottom and topsides they could be diagonally planked using short pieces. The bottom could be double-diagonal and the topsides diagonal inner and fore & aft outer layer. In this case I would fit an outer chine log to cover the bottom planking end grain.

    If cross (diagonal) planking the bottom the planking should run chine to chine. If longitudinal planking is used you could build the outer keel 1" taller and fasten it directly to the apron, forming a garboard rabbet.

    [​IMG]
     

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