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Thread: Plywood Canoe Concept - Birchbark Style

  1. #1
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    Default Plywood Canoe Concept - Birchbark Style

    Here is the design of a plywood canoe employing the basic idea of the birchbark canoe.

    This simple pattern for a very crudely shaped canoe I found on a German Forum got me thinking.




    I was interested to see what shape could be made up with a more refined pattern.

    So itís model building time again.

    This is my pattern:



    And here is the paper model:




    It is amazing what a subtle shape can be achieved with such a simple method.

    But there is also a weakness in this concept. Although the bottom of the hull is nicely shaped when you take a close look you will see there are pointy spots at the turn of the bilge and the area between the cuts is cylindrical.
    In theory an infinite number of cuts would solve this problem but I am looking for a more practical way.

    If you first fill these spots on the inside with epoxy you can sand down the peaks on the outside to achieve an almost fair hull.

    Last edited by flo-mo; 07-23-2017 at 02:59 AM.

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    Default Re: Plywood Canoe Concept - Birchbark Style

    After sanding, priming and painting this is the result.





    For the paper model this method worked out nicely.

    Next step is to see if this is also true for a 1:10 scale model made of plywood.





    The plywood model showed me that there are several things to reconsider but in principal it should be possible to build this canoe full scale (LOA: 15' 4", beam: 35", center depth: 14").

    By the way it would consume two sheets of 4mm plywood.

    As far as I know the Stillwater designs used a similar method but unfortunately as I heard they went out of business.
    Last edited by flo-mo; 07-28-2013 at 09:18 AM.

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    Default Re: Plywood Canoe Concept - Birchbark Style

    Fantastic. Will you sheath the finished product with glass and when will you post a link to your dimensions so I can build one?

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    Default Re: Plywood Canoe Concept - Birchbark Style

    +1.
    "A man builds the best of himself into a boat- builds many of the memories of his ancestors." -Steinbeck

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    Default Re: Plywood Canoe Concept - Birchbark Style

    Again you astonish me with a delightful design.
    Await dreams, loves, life; | There is always tomorrow. | Until there is not.

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    Default Re: Plywood Canoe Concept - Birchbark Style

    Bear with me while I define darts. Women's clothing uses darts- long, narrow triangular cuts to help flat cloth conform to curved surfaces. So we are all familiar with the concept and have seen many examples.

    The Stillwater canoes were made in two halves and had only 2 darts in the 11 1/2 foot boat an three in the 16 foot boats. The center joint has to be cut back from about a half inch at the gunnel to 0 at the keel, to make the joint at the center. The darts on the 11 1/2 ft boat were about 12 and 24 inches from the center and 9 and 6 inches deep, respectively.

    There will be lumps. 3mm Okume is the best material. Stillwater taped the seams on the inside and sheathed the hull with 6 oz cloth.

    My daughters and I are currently building a stretched Dusk (12'8") and have been working out the dart locations and widths by trial and error. Lots of error. The panels can be wrapped around the forms without cutting darts. They will buckle slightly and help you decide where the darts belong. You can reduce the lumps to some extent by using a 3" wide 'butt block' made of 3mm okume on the inside of the dart clamped with screws and blocks of wood. Grain direction has a huge effect on stiffness. Match the grain direction of the panel. Many details need to be worked out, but the keys to the shape may be the dihedral angle set in the panels at the start and certainly the depth, width and location of the darts.

    I wrote the long winded description below some time ago, and includes some foggy recollection of some problems that may have resulted from failure to follow all of the directions, such as taping the outside of the center seam, which is hard to access from the inside. I emailed it to the OP some time ago and now I see that it needed some editing. With some minor editing here, there will be a lot of unanswered questions.

    The boat is constructed from four panels, assembled in two halves and joined at the center. I bought the plans ($50 for building one boat) not the kit.



    The first step is to join two 3mm okume plywood panels at a slight angle with a fillet of thickened epoxy and a strip of fiberglass tape. The angles are 165-167 degrees. The stations are one foot apart starting at the center of the boat. Station 1 is the center. There are only 3 stations used, 1 and 3, are 2 feet apart and "station 4A' is an angled block on the inside at station 4. A strap is wrapped around the panels at a distance between Station 4 and the stem that brings the panels to the 150 degree angle at station 4. The block is not used to pull the panels; it is a reference to get the correct angle.


    The second/third step is to form the ends of the boat one at a time, resulting in two half canoes. Once the initial angle fillet has hardened, the panels are wrapped around Stations 2A and 3A using a strap looped around the station over the plywood. Temporary gunnels about 3/4" square (exact size not important) are clamped to the edge of the panels and help form the panels as they are wrapped around the forms. The stations are mounted on a strong back. As the panels are wrapped around the forms, the small cutouts in at the sheer will close. (Or can be closed with wires as or before the panels are wrapped around the forms?)

    I found that the stem wanted to meet at the sharpest point of the stem curve and would not close easily on either side. The first stem cracked and had to be faired with filled epoxy. On the second half, I eased the stem curve about 1/4 inch and the stem went together easily.

    The plans and instructions say to do this one at a time, so you only need one set of forms. Note: After the panels are cut out, the curved part at the stem is beveled 45 degrees so the stem will meet on a flat surface, not an edge. The cuts in the shear are taped (glass tape and epoxy) on the inside, the stems are taped on the outside and filleted on the inside. The ends of the cutouts below the shear can not be faired perfectly on the outside of the boat. There will be a hump similar to a birchbark canoe.


    Next step is to join the halves of the boat. They will join to form a badly hogged shape. Line them up with or without a slight rocker and cut away material toward the shear until they fit with the desired rocker on the keel. This is a simple spiling job since the sheers will touch with a gap at the keel. Straight, parallel lines marked, one on each half, will cut off four narrow wedges to allow the halves to meet.


    The joint is taped on the inside (and out? I think I started on the outside, then taped the inside and sanded away most of the outside tape when fairing the joint).


    The hull is sheathed on the outside with 6 oz fiberglass. There is a 3 inch wide sheer strip (3mm plywood) added to the sheer on the outside of the boat. It is not a sheer strip in the usual sense. It is more of a thickness doubler that does not extend above the edge of the hull panel. It is made from 4” strips and spiled to fit. If you work quickly and use slow hardener, the shear double can be clamped on and bonded to the still wet fiberglass.

    Departure from instructions #1)
    The initial angle joins the panels in a dead straight line from the center to station 4. [At station 4, a third form, a short piece of stock with a 150 degree outside angle is loosely placed on the inside of the panel at station 4, and locates the end of the fillet. The panels are pulled up with a strap somewhere between station 4 and the bow until they match the angle of the 150 degree block.] I saw no reason to cut 4 panels and stitch pairs back together in a straight line. The angle is sharper than the panels can be bent, but by cutting a kerf half way through the panels, they are very flexible, as well as fragile, and they can be angled easily without stitching. No alignment problem is possible this way, and there is no seam on the outside.

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    Default Re: Plywood Canoe Concept - Birchbark Style

    There was one builder who brought some boats to the Mid Atlantic Woodenboat Show in St Michaels a couple years that were built that way. Even though he did a good job making them as fair as possible, I never liked the look. As long as the bottom has a compound shape, I suspect that either there will be kinks at the end of the dart or the darts will go all the way to a flat part of the bottom or the keel.
    Tom L

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    Default Re: Plywood Canoe Concept - Birchbark Style

    I made photos of the build of another paper model (slightly modified version). With paper itís an easy build and even though it will be much harder I am optimistic that it will be possible to build the canoe full scale with 4mm plywood. The sequence of assembly will be the same.

    Cut pattern:


    Panel alignment:

    The hatching marks the scarf-joint. The elongated rectangle along the keel line stands for a glass reinforced butt joint.



    So all panels are connected:


    Closing the slots bends the panel in a curios way:


    Attaching the gunwales:


    Ready for taking the final shape:

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    Default Re: Plywood Canoe Concept - Birchbark Style

    An astonishing transformation takes place as soon as the gunwales approximate:


    Transformation accomplished:





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    Default Re: Plywood Canoe Concept - Birchbark Style

    The shape of the canoe is due to the cut pattern and the material properties of the plywood/paper – no stations needed.

    To bend 3mm Okume will be easier (lower bend radius - the bilge will be quite firm) but I think for a canoe of this size (LOA: 15' 4", beam: 35", centre depth: 14") even if the hull is sheathed inside and outside with 6 oz. cloth it will still need reinforcement (ribs or something else).

    With 4mm Okume bending will be a struggle (higher bend radius - the bilge will be softer) but if you succeed to persuade the plywood to do what you want to, the structure should be quite rigid and sheathing the hull inside and outside with 6 oz. cloth might be all there is to do.
    Last edited by flo-mo; 07-30-2013 at 09:55 AM.

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    Default Re: Plywood Canoe Concept - Birchbark Style

    I think that you will find that sheathing the inside with glass is not necessary, at least for a canoe up to 16 feet long. I don't know where to draw the line, but it should be fairly obvious once the outside has been glassed. Since you glass the outside first, you will be able to evaluate the need for an inner layer of glass easily enough.

    One layer of 6 oz cloth on the outside only of the 3mm hull was more than adequately stiff on the 11 1/2 foot Dusk. There is 2" wide a strip of tape on the inside of the darts. The Dusk does have a 3 inch wide strip of ply laminated to the hull at the shear, call it a 'shear streak' for lack of a better term. A slightly heavier gunnel would compensate for the shear streak.

    4 mm is about twice as stiff as as 3 mm, (64:27), but considering how easily 3mm conforms, it might not be too difficult to work with. From what I have read, nothing thicker than 3 mm can be deformed successfully. Considering the amount of effort that has apparently gone into developing that opinion, 4 mm might work pretty well. It will be interesting to find out how it works out. I would expect that the weight penalty on a smaller hull would argue against 4 mm. For a larger boat, the extra stiffness will be needed, and the gentler curvature will make the thicker plywood easier to work with.

    I question the center scarf idea. It might be problematic, but the best way to find out is to try it. Good luck, I think a lot of us are anxious to see how well you work this out.

    OK, 4mm works ...and 3/16" (5mm) which may be close to the limit Tortured-Plywood-Hulls.html
    Last edited by MN Dave; 03-06-2014 at 09:30 PM. Reason: no point posting whole new reply for one more line

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    Default Re: Plywood Canoe Concept - Birchbark Style

    A canoe design form the Sixties with more or less the same concept (there is also a nice story connected with this design: How we fell in love, built a canoe and got a house):





    More photos of the build: http://cozybookbasics.wordpress.com/...y-8-steps-pix/

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    Default Re: Plywood Canoe Concept - Birchbark Style

    A light weight rowboat maximising two sheets of plywood based on the same concept:














    Length: 489cm (16’)
    Beam: 124cm (48 7/8”)
    Design Displacement: 135/225kg (300/500 lbs)
    Waterline Length: 477.5/482cm (15’ 8”/15’ 10”)
    Waterline Beam: 74/85cm (29 1/4“/33 Ĺ”)
    Draft: 10.3/14.2cm (4“/5 5/8”)
    Wetted Area: 2.35/2.89m^2
    Surface Area: 6.00m^2
    Approx. Bare Boat Weight: 30kg (67lbs)
    Prismatic Coeff. : 0.54/0.56
    Block Coeff.: 0.37/0.39
    Bow/Stern Height: 58.5cm (23”)
    Midship Depth: 35.5cm (14”)

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    Default Re: Plywood Canoe Concept - Birchbark Style

    That one's enticing.
    "A man builds the best of himself into a boat- builds many of the memories of his ancestors." -Steinbeck

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    Default Re: Plywood Canoe Concept - Birchbark Style

    Love those shapes.

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    Default Re: Plywood Canoe Concept - Birchbark Style

    Very interesting. It is somewhat similar to Gib Etheridge's Chris dory and the Adirondak guideboat but with slacker bilges and more flare. It would be interesting to row.

    One way to flatten the hull at the darts is to add butt blocks on the inside about 3" wide made of the same plywood as the hull. The grain should run the same direction as the hull panels. It does depart from the extreme conservation of plywood concept though. The butt blocks flatten the humps and allow for considerably more stock removal when fairing the hull. I clamped them on a similar canoe by running a drywall screw through short blocks inside and out. The screw passes through the dart so the holes are not obtrusive when filled.

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    Default Re: Plywood Canoe Concept - Birchbark Style

    I have just come across this thread and found it very interesting I was looking to build a canoe as I am on a budget and have only a borrowed space I could build in, this concept appeals has it been tried full size and will it work? Would 4mm ply take the shape easily?

    Dave
    Last edited by bbdave; 03-17-2014 at 11:50 AM.

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    Default Re: Plywood Canoe Concept - Birchbark Style

    The idea of cutting darts comes from the technique used by the birch bark canoe builders. But plywood, even 4mm plywood, is much stiffer than birchbark. When each dart is closed up for gluing a hump is formed at the point of the vee. If you try to sand it down you may go thru' the ply or ,at least, develope a weak spot.
    The designer of the ultralight canoe, Sweet Dream, Marc Pettigill, had to use four darts in his design. They don't show because he planed thru' two of the three veneers and strengthened the spot with the fiberglass tape that seals the chine seam.
    And, so far, no one has said they have built the design you are interested in. By the way, it's a double ender rowboat. It's much wider than a canoe.

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    Default Re: Plywood Canoe Concept - Birchbark Style

    Darts may not be a huge deal out on the real water. Remember the original Sportspal and Radisson canoes. They used a one-piece aluminum sheet to make the skin with welded darts in it and then lined the hull with ethafoam and a few aluminum ribs. They weren't exactly zippy by cruising canoe standards, but did the job and were popular with hunters and fishermen.


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    Default Re: Plywood Canoe Concept - Birchbark Style

    Zero plywood torturing experience here, so take this with a few grains of salt.
    I'm wondering if the dart joints could be slightly smoother if the joint was a zig-zag "finger" joint, instead of the straight line shown. You would still have a point to be faired, but no butt joints. You'd probably have to use ratchet straps acting on hot-glued blocking to pull the joints together...

    Another (probably worthless) thought was to use the 4mm material, but plane or sand away 1mm of material along the path of the inside of the tightest bend. I think you'd have to be pretty consistent in path and uniform in both thickness and transition, as inaccuracies would probably "telegraph" thru.

    I can see how the "simplicity" of single-panel building is both alluring and tricky.

    Chip

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    Default Re: Plywood Canoe Concept - Birchbark Style

    I was thinking if I put ribs where the darts are they could be sanded pretty fair I'd probably use 3mm then glass inside and out.
    My main concern was if the idea works in full size I have built a couple of paper models which seem to work a ply model is next so fingers crossed.

    Dave

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    Default Re: Plywood Canoe Concept - Birchbark Style

    Quote Originally Posted by Chip Chester View Post
    Zero plywood torturing experience here, so take this with a few grains of salt.
    I'm wondering if the dart joints could be slightly smoother if the joint was a zig-zag "finger" joint, instead of the straight line shown. You would still have a point to be faired, but no butt joints. You'd probably have to use ratchet straps acting on hot-glued blocking to pull the joints together...

    Another (probably worthless) thought was to use the 4mm material, but plane or sand away 1mm of material along the path of the inside of the tightest bend. I think you'd have to be pretty consistent in path and uniform in both thickness and transition, as inaccuracies would probably "telegraph" thru.

    I can see how the "simplicity" of single-panel building is both alluring and tricky.

    Chip
    OK, limited experience here. I'm on my second tortured boat. The Stillwater Dusk is downright zippy for 11 1/2 ft, so don't put too much stock in the comparison to the aluminum thing.

    The darts do more to relieve compressive stresses as the panels are wrapped around the molds in the Stillwater Dusk. The gunnel end of the dart fairs in nicely. The hump is at the point of the dart near the turn of the bilge. You can flatten it some by adding a piece of plywood on the inside and clamping while the glue sets. Doubling the thickness for a few inches around the dart allows for plenty of fairing, but also results in a bulls eye if you finish bright.

    It might be possible to flatten the hump by cutting some wood away at an angle to the dart, whether a perpendicular cut, or 2 cuts at 120 degrees, I don't know. It could just get worse. On the whole, the humps are not pronounced. If you are looking for perfection, this is a darned good compromise, but not perfect. Who is it that says perfect is the enemy of good?

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    Default Re: Plywood Canoe Concept - Birchbark Style

    The idea of this approach was to create a "simple" method of construction. With all the input about how to remove the distortions (looks like 16 distinct humps)and talk about glassing and clamping the technique appears to be anything but "simple". And not cheap if it is glassed inside and out.
    And introducing the need to "torture" the panels to get the desired shape introduces an element that is not well understood. Chris Kulczycki, who designed the two most well known tortured ply kayaks, Yare and Severn, posted an account of what he went thru to get the hull he wanted. He found there was no easy way to reproduce the hull on the plans because toruring did strange things to the ply. In the end he used trial and error, building about 6 hulls 5 of which ended up on the scrap pile. I built the Yare from Kulczycki's book and just getting thru' the process with a complete set of instructions was a a head-banger. In the end I caused a hook in the keel and had to open the rear half of the keel seam to get things straightened out. It was a sweaty proposition caused by my use of an 8' straight edge instead of a flexible batten. The difference on each plank was only about 1/4".
    If you want Simple, Cheap and Fast-to-Build a three panel pirogue like "Cheap Canoe" is the way to go. The plans are free.You need 2 sheets of 1/4" ply,a bucket of epoxy, 50 feet of 4" glass tape,a small roll of 18 ga.copper wire about a pound of wood flour. A little dimensional lumber for rub strips and breasthooks will make it look better. Not sexy but no head banging required.

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    Default Re: Plywood Canoe Concept - Birchbark Style

    To my eye, Stefan has achieved an elegant use of material. The 16 humps will be quite small, but as any irregularity in a smooth shiny surface is easy to spot, there is plenty of opportunity to critique the technique. Some small humps vs lots of chines? If you hate little humps, this isn't your dream boat. Then again, nightmares are dreams too.

    If you want Simple, Cheap and Fast-to-Build a three panel pirogue like "Cheap Canoe" is the way to go. No argument. If that is your only priority. If you want something more sophisticated, there are many alternatives, and tortured ply is one of them. This is a discussion about one way to build a boat, and there are other threads about skin on frame, strippers, stitch and glue, traditional Adirondack Guide boats, etc. None of them s the holy grail. All of them have their place.

    The 11.5 ft Dusk has 4 darts and a midsection join. It is built in two identical halves and then butted at the center. The center joint is smooth, and the rest of the hull is no more difficult than any other stitch and glue hull, except for a lot less stitching. Everything goes together as designed with no difficulty, except for a minor problem with the stem profile. If you trim the stem back 1/4 inch where the turn is sharpest, it is much easier. I think that Lewis put a lot of effort into getting it just right. The design was well thought out and is easily assembled. You will be hard put to make a better round bottomed hull from flat sheets.

    The Stillwater kit had 4 panels. There is a dead straight joint along the keel, which needs to have something of a crease (shallow V) set with a fully cured fillet before wrapping the panels around the forms. When I built from the plans, I did not separate the two panels along the keel. I cut a kerf to avoid having to realign and stitch the 3mm panels while still taking a sharp bend. Point is that I only stitched a total of 10 feet of seam and none of it took much stress on the wire.

    My second hull is an attempt to get another foot or two out of the 2 sheets of plywood. Starting form scratch is an interesting exercise. We tried some things and tried to estimate new dart locations based on the way the panels buckled as the plywood was wrapped around the forms. The darts are narrower than you might expect. The dart towards the end is not perpendicular to the gunnel in the Dusk, and how Lewis settled on that angle is not obvious, but it worked. I tried some experiments to reduce the minor humps. It isn't complicated, and if it ever warms up, I will get back out to the garage and finish the boat and see how well it worked. Is the development of a new design using this technique a head banger? You betcha! Can the bugs be worked out? Yeah. Is it worth it? To each his own.
    Last edited by MN Dave; 03-19-2014 at 11:24 PM. Reason: wordsmithing

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    Default Re: Plywood Canoe Concept - Birchbark Style

    https://www.facebook.com/photo.php?f...7&l=cfa0433363

    Interesting discussion. I just finished a canoe like this from 2 sheets of 5mm okoume marine grade flexoply. My first boat ever, so plenty of room for improvement. And yes, there are some humps where darts end, but frankly, my dear, I don't give a a damn

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    Default Re: Plywood Canoe Concept - Birchbark Style

    Eliminating the bump is one of the constant torments of tortured plywood.
    I have tried putting a 1" diameter hole at the end to relieve the stress concentration.
    Not a whole lot of joy with that. I wonder, in this case, if a stringer glued inside the skin at the time of installing the gunwales would serve to straighten out the bilge bumps. Otherwise it's pretty topugh to build something that is a compound shape and fair within the .1mm thickness of the plywood veneer without some sort of jig.
    SHC

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    Default Re: Plywood Canoe Concept - Birchbark Style

    After many models in different materials and sizes, the biggest 240cm I feel confident and am soon starting my full scale canoe. A slightly edited version of Flo-mo's plans who deserves all credit. Exciting times!

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    Default Re: Plywood Canoe Concept - Birchbark Style

    Quote Originally Posted by Thestripper View Post
    After many models in different materials and sizes, the biggest 240cm I feel confident and am soon starting my full scale canoe. A slightly edited version of Flo-mo's plans who deserves all credit. Exciting times!
    Welcome to the forum. I am looking forward to your build.

    Lofoten Islands -- that sounds like a remote but awesome place with quite some boat building history.

    A few results from a quick google search:











    Last edited by flo-mo; 07-21-2014 at 12:08 PM.

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    Default Re: Plywood Canoe Concept - Birchbark Style

    Back to the plywood birchbark-style canoe:

    Corresponding with the gentleman from Norway induced me to update my website.
    Under the name of "Gorewood 16' Canoe" you can find a PDF-download with the offsets for this design.

    I started the build of a variation of this design, a light weight 14' solo canoe and a build thread will follow soon.
    Last edited by flo-mo; 07-21-2014 at 12:04 PM.

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    Default Re: Plywood Canoe Concept - Birchbark Style

    Interesting discussion her about all these plywood concept canoe - birchbark styles.
    Take a look at these guys one in Germany, the other in the United Kingdom.
    Judge for yourself, but for myself I have still to see better plywood concept canoe-birchbark styles.
    http://www.open-canoe-journal.de/jou...agnercanoe.htm



    https://www.facebook.com/NorthernSou.../photos_stream ....... the Englisch guys


    https://www.youtube.com/watch?v=x1KdAdTh5CY

    https://www.youtube.com/watch?v=D5zVWh5lCls

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    Default Re: Plywood Canoe Concept - Birchbark Style

    Might I take this opportunity to offend all by suggesting this design could be readily built in .100 aluminum plate.

  32. #32

    Default Re: Plywood Canoe Concept - Birchbark Style

    What is your point?

    Sears made a nice aluminum canoe back in the 80's and they didn't need to cut darts into it to make it. Grumman too.

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    Default Re: Plywood Canoe Concept - Birchbark Style

    Quote Originally Posted by trent hink View Post
    What is your point?
    Only that this ingenious design can be built in a variety of panel stock. Of course, a boat slathered in epoxy and fiberglass, but with a plywood core, is generally regarded as an honest to goodness real wooden boat.

    I've built several wooden boats and do appreciate the materials and the process. I've also helped build a variety of aluminum boats, many originating from designs intended for wood construction.

    I do appreciate the unique characteristics of aluminum as a boatbuilding material. However, the process of putting together an aluminum boat is generally less than pleasant. For a canoe that will see severe service and little or no maintenance, and be kept out in the weather for years on end, aluminum would be worth considering.
    Last edited by TerryLL; 08-19-2014 at 06:38 PM.

  34. #34
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    Default Re: Plywood Canoe Concept - Birchbark Style

    Herr Wagner's poducts are exceedingly pretty. They should be high quality because it is known he has been practicing for 30 years. Herr Wagner seems to want the technology kept a secret because the technique involved has only been shown in a film that was reduced in time to about one minute. From what little Ive seen in the picture the hull has somehow been planked on the inside and a layer of ribs added. I do not see the technique as a worthwhile pursuit until someone knowledgable comes up with video or still photos that show the important parts of the process.

  35. #35
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    Jul 2011
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    Default Re: Plywood Canoe Concept - Birchbark Style

    I think that Herr Wagner would be baffled by the criticism. He put a lot of work and information into the video. It was not intended to teach you how to substitute thin plywood for birch bark, but it does show that a very similar process will result in a very similar boat. He was showcasing his art, that's all. The lack of useable instructions may be disappointing, but that wasn't the intent.

    Wood and canvas construction was another way to substitute 'modern' materials for the dwindling supply of birch bark. By substituting a heavy complicated mold and a much more flexible skin for the bark, the loose planking and bent ribs shape can be by stabilized and waterproofed by a stressed skin to form a similar structure. In the case of wood and canvas, the planks are not captured between the skin and ribs, so they have to be tacked to the ribs until the skin is applied. The plywood skin is much closer to the original bark in most respects. Unlike wood and canvas, if you can build one of these, you could transfer those skills to bark. If you can build with bark. you can build with thin plywood. It is a good way to substitute modern materials to make a very similar boat. The traditional construction techniques for birch bark canoe construction are preserved and can be learned even where good bark is unavailable.

    The shape of a birch bark canoe is determined by the way ribs and planks work against the skin to form the boat. It looks to be considerably heavier and more robust than a tortured plywood canoe. Both shapes depend on removing darts from the skin to warp it to the desired shape. the tortured plywood forces you to figure out what to remove without the benefit of a form to hold the shape while you cut away the highly compressed bits.

    Aluminum? This is the wooden boat forum, and the rampant use of composites is bad enough.

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