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Thread: Plywood Canoe Concept - Birchbark Style

  1. #106
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    Default Re: Plywood Canoe Concept - Birchbark Style

    Quote Originally Posted by SHClark View Post
    I understand how the darts work. It’s pretty obvious to anyone who h as ever tried to compound bend plywood.
    My idea comes from sailmaking. Assume you want to tighten the leech, you could open the seams and increase the overlap. Akin to taking the gore cuts. The alternative is to split the seam in the middle and stitch it back together with less overlap. Letting the middle out rather than pulling the edges in. Some sailmakers have done shocking things with knives and sail repair tape on the way to the starting line.
    I was thinking that the slots would end up being 6” or so every foot. They wouldn’t have to cross the centerline, just provide enough relief for the center of the panels to stretch enough to prevent the edges from buckling.
    It should come to the same thing.
    I have built more than a few tortured ply boats, I didn’t mean any offense.
    SHC
    Offense? I was just trying to explain why I thought it wouldn't work. I had no way of knowing that you had built any of these. I wasn't offended until I found out that you have made more than a few tortured plywood boats and I haven't seen any pictures. Yer holdin' out on us!

    If you look at the picture in Link to Post #95,, you can see what the panels do when wrapped around forms with no cuts. It looks to me like there is either too much wood at the sheer or too little all across the middle. Stefan explained somewhere how he modeled the canoes on his computer then laid the surface flat to locate the cuts. He explained it a lot better than I can.

  2. #107
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    May 2009
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    Vienna, Austria
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    Default Re: Plywood Canoe Concept - Birchbark Style

    Another addition to the Gorewood design family: The Fat Gorwood Canoe


    Actually this is a refined version of one of the very early stages of the design development which at the time I didn't further engage in as its midship section was too wide and too deep for my liking (scale model in the bottom right corner).



    Recently I was searching for a design of mine that would have similar characteristics as Storer's Viola 14 sailing canoe. The closest one I found was this early stage design. It is more stable than most common canoes, but not quite as stable as the Viola 14.
    So eventually I ended up developing a completely different sailing canoe (Flywood Two Sheet Sailing Canoe).


    Still for some people this fat canoe might be what they are looking for. If you don't care much for speed but want a canoe that could also be sailed without being too tipsy and offers more capacity and more freeboard, this one might be an option.

    LAO: 478 cm
    Beam: 95 cm
    Midship Depth: 40 cm




    Comparison Flywood Two Sheet Sailing Canoe and the Fat Gorewood Canoe:



    Offsets for the Fat Gorewood Canoe (click image for PDF download):
    Last edited by flo-mo; 03-03-2021 at 10:37 AM.

  3. #108
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    Jun 2014
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    Lofoten Islands, Norway
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    Default Re: Plywood Canoe Concept - Birchbark Style

    It's good to see that you are developing new Gorewoods! I like the concept idea of the Fat G and that it could serve as a good sailing canoe. Do you have some section drawings showing the approximate rocker and cross section hull shape? As always, impressive work flo-mo!

  4. #109
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    Default Re: Plywood Canoe Concept - Birchbark Style

    Hi Johan,

    Here is a picture that somewhat gives an idea of the rocker and the cross section amidships. As it is derived from the small scale model made of paper it is really just an approximation.

    To a degree the rocker can be regulated by the distance at the sheer, especially with this building method. When you start the "metamorphosis" you have excessive rocker. The further the two shears come together, the more the hull stretches out. So more flare means more rocker -- if you introduce more tumblehome you will reduce rocker.

    Depending on the designated use of your canoe it is up to you to decide which shape you prefer.

    Last edited by flo-mo; 03-03-2021 at 07:38 AM.

  5. #110
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    Default Re: Plywood Canoe Concept - Birchbark Style

    Just a minor correction on the dimensions of the Fat Gorewood Canoe:

    LAO: 477 cm
    Beam: 95 cm
    Midship depth: 39 cm

    The measurements are taken from the small paper scale model and therefor not really accurate. Also the change is almost insignificant, but still I try to get the numbers right. This is why I also updated the plan for the offsets. I rearranged the layout, but aside of correcting LAO and depth by one centimeter respectively everything else is the same.

    Here is the updated plan (again click the image for PDF download):

    Last edited by flo-mo; 03-03-2021 at 10:34 AM. Reason: typo

  6. #111
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    central cal
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    Default Re: Plywood Canoe Concept - Birchbark Style

    I’m holding out for that sailing canoe. My duck punt is lonely.

  7. #112
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    Default Re: Plywood Canoe Concept - Birchbark Style

    Peter R has used the English lockdown to design and build his own Gorewood canoe.




    It is based on the very first Gorewood canoe that I built, the Gorewood 14, but has a shear 3 cm higher. The exceptional craftsmanship he demonstrated in building his canoe and the ingenuity he showed in solving tricky problems are remarkable. In addition, Peter has excellently documented the entire construction process in pictures, words and video recordings.




    If you are interested in this special construction method, I recommend you to have a look at his blog in the Song of the Paddle Forum: https://www.songofthepaddle.co.uk/fl...re-t58748.html
    You will hardly find a better building instruction.


    p.s.: I envy Peter for being able to use exactly the plywood I always wished I had used to build my canoes.

  8. #113
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    Jan 2021
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    Perth, Western Australia, Australia
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    Default Re: Plywood Canoe Concept - Birchbark Style

    such a nice build to watch.

  9. #114
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    Jul 2020
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    Evans, Georgia, USA
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    Default Re: Plywood Canoe Concept - Birchbark Style

    How the heck does Peter keep his shop so freaking clean while he is working? Are there little elves that come out between video frames to sweep up?

    That was a nice video. Lots for a beginner like me to learn from it. I like how he has all of his tools and clamps laid out on the very large work table before he starts needing them. I also like his method of bending the gunwales into shape with the zip straps. Was he using a steam iron only? I thought I saw him painting something in the hull while he was bending and steaming?
    “If everybody is thinking alike, then somebody isn’t thinking.”
    “You’re never beaten until you admit it.”
    - General George Smith Patton

  10. #115
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    Feb 2006
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    Pennsylvania
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    Default Re: Plywood Canoe Concept - Birchbark Style

    Quote Originally Posted by Lee.007 View Post
    How the heck does Peter keep his shop so freaking clean while he is working? Are there little elves that come out between video frames to sweep up?
    Right. Shops like that drive me nuts. He's built a lot of boats, but the floor is immaculate.
    -Dave

  11. #116
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    Default Re: Plywood Canoe Concept - Birchbark Style

    Since the shape of the canoes I have made using the Gorewood construction method is influenced by a variety of factors (cutting pattern for the panels; thickness and type of plywood; wood type, thickness and grain pattern of the wood veneer of the plywood, or generally speaking, the bending behavior of the plywood), it is very likely that each canoe is unique and can hardly be replicated a second time in exactly the same shape.

    Nevertheless, it is of course interesting to get an idea of how the Gorewood canoes actually built look and what the significant characteristics are.

    In order to present this in a comprehensible way, it has always been my intention to take the lines off the hulls of these canoes and subsequently create 3D models that provide the basis for hydrostatic calculations.

    However, this process is quite time-consuming and for the longest time I lacked the motivation to deal with it. Only when I realized what amazing possibilities photogrammetry offers even to the interested layman, I decided to document my 4 canoes with the help of this technology.

    More info on photogrammetry: http://forum.woodenboat.com/showthre...photogrammetry

    Here are the results:








  12. #117
    Join Date
    Jun 2014
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    Lofoten Islands, Norway
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    Default Re: Plywood Canoe Concept - Birchbark Style

    It's been a while since I posted here last time. Since that time, many beautiful Gorewood style canoes have seen the light of day. There has also been some less successful, but equally faithful attempts at the build. Even the attempts that came to a cracking halt seem to have brought some joy to the builder. That's how it was for me. It was a thrill! Things are in high tension and you don't know if this is going to work...

    I used two sheets of three-ply popplar plywood. I think it measured 3.7 mm thick, under 4 anyway. At the hardware store I took the top most sheet in the stack. After a quick inspection I was impressed and put it aside. Then I went through the whole bunch, maybe 35 sheets of plywood but there wasn't another good sheet. Looked like they either had some poorly laid out core layers, or the face layer had some tiny but long cracks. There were even some with eyes almost 2" big. I Picked out the one I thought was best. It had good flat core land face layers, no really big eyes but some some thin short cracks. It turned out the first plywood, the nice one, stood up to the test. The other one didn't.

    I used five days to slowly close up the canoe. I went real slow towards the end. Almost inaudible sounds caught my attention on the fifth night. I had added a little tension to the straps earlier that night. I just stood there trying to hear where the tiny and sporadic sound came from. Just as I thought I had localized the sound as coming from the bow area a loud and sharp crack shook the room. My eyes were on the gunwale when it happened and I just picked up that something indeed moved quite a bit. It turned out that the hull had cracked in two places at the same time. These were totalt cracks through all the ply-layers. Below the bilge near the keel, about one foot from the bow and stern. Each crack about 1.5 foot long or so and they were both on what I had previously judged to be the bad sheet. I let it rest for a few days and then closed up the hull without any more bad cracks happening.

    The tension released by the two cracks had caused the hull to bend. Midships the shape looked quite intact but the bow and stern looked like great fishtails pointing in opposite directions. The panels wanted to flip inwards creating a convex area on the front right, and back left ends of the canoe. I stuck a piece of wood inside the bow and stern to visually fix this as I contemplated the over all shape of the canoe over a few days. The hull came so close that even though I didn't want to spend glass and epoxy on it, gave me confidence that this method will work. I was thinking that revising something in the plans or using hot steam or such would do the trick. It has later been established that the right plywood will accept becoming a beautiful Gorewood canoe. Anyways, I hope you will enjoy this little flash from the past.

    Thanks to flo-mo!
    Attached Images Attached Images

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