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Maximum Plank Width

Discussion in 'Wood and Canvas' started by Bruce Whittington, Sep 17, 2018.

  1. Bruce Whittington

    Bruce Whittington Curious about Wooden Canoes

    After a guitar-making hiatus, this summer I returned to the restoration of my old 17' Chestnut cruiser. I am pushing to get ready for canvas before the bad weather sets in in earnest (with no warm dry place to work.) I have been replacing planks, renailed rib tops etc. and was planning to replace the top tier all around. I would like to use planks up to 7" in width at widest point for the top tier at either end. In the photo, I would replace the existing top plank on the near side that tapers to a point, and the one below it, from the filler compound forward with one wide plank to go all the way to the stem. (Two planks below at the stem would be infilled.) Maximum width is near 7", less most of the way. I have some excellent fine edge grain redcedar for the purpose. Is there any reason not to do this? There are no serious curves in this area. (Don't know what the black bar is below the scarf joint in new inwale tips . . . ) IMG_6369 copy.jpg
  2. Dan Lindberg

    Dan Lindberg Ex Wood Hoarder

    Waiting to hear what the pros think.
    I wouldn't because when I process planking stock (for a given project), it's all the same width.
  3. MGC

    MGC Paddlephile

    To be clear, this is not a "pro"'s an armchair quarterback opinion.
    You may make the boards as wide as you want to...there is no reason that you have to use narrower boards other than to duplicate the original construction. Keep in mind that Rushton canvas boats all have a 9 inch sheer plank...and many builders run a wider board up to the tips of the rails. The reason many of us would not do that is that we don't have a good way to make such wide planks..on my saw I'm happy to get 4 inches...never mind seven.
    I'd be a bit leery about using such wide red cedar..I think it would give you more trouble (as it's pretty brittle) than white cedar. For that reason alone I would probably stick with the narrower planking.....
  4. rbudge

    rbudge Curious about Wooden Canoes

    Don't do it. Wider board will be exposed to more movement due to changes in moisture content than narrower board. The result will be cracking and splitting. A thicker plank than a canoe plank might have a better chance to survive as it can possibly be fastened in such a way as to reduce the amount of wood between rows of nails. If it is installed dry, the plank could expand enough to cause bulges at edges and even in the middle of the plank after it has taken up water in use. I have a canoe built with 4" plank that does this. When dry, there are gaps between the planks. When wet, the seams bulge and are visible under the canvas.
    My opinion is that a canoe plank should be no more than 3" wide. Edge grain will help reduce the problem some, but 7" is still too wide.
  5. Fitz

    Fitz Wooden Canoes are in the Blood

    I once worked on a big, 20 ft, old Huron canoe. Some of the flat sawn, white cedar planking on the canoe was very wide. I seem to recall up to 9 inches. There was a great deal of cupping going on in the planking on that canoe.
  6. Just1moredave

    Just1moredave Curious about Wooden Canoes

    You can look up the radial expansion of western red cedar. I would try just measuring the planks you have. Measure the dry width. Soak for a while. If you can soak the plank vertically, you can mark the height it floats to at first, then soak it until it stops losing height, when it will have absorbed as much water as it can. Measure again. The sheer plank allows you to leave room for some expansion.
  7. Dave Osborn

    Dave Osborn LIFE MEMBER

    What Fitz said....
    Wide, flat sawn white cedar cups, in my experience.
  8. Dave Osborn

    Dave Osborn LIFE MEMBER

    Cupped planks on a Bob’s Special.

    Attached Files:

  9. OP
    Bruce Whittington

    Bruce Whittington Curious about Wooden Canoes

    Thanks for the replies. For the record, the cedar I have available is fully quartersawn, old growth heartwood, 24 - 30 growth rings per inch. It is good enough that I am thinking about cutting some of it for guitar tops. So I do think it is less likely to cause problems than younger or flat sawn woods. But bearing your comments in mind, to be on the safe side, I will use narrower widths, even if it means cutting large pieces and fitting them and then ripping them into two pieces. I don't want to have to redo this . . .
  10. Gary Willoughby

    Gary Willoughby Boat Builder

    Guess I don't understand why you just don't do it the way it was built. Why would you change something that works ? But than again it's your canoe do what ever you want.
  11. OP
    Bruce Whittington

    Bruce Whittington Curious about Wooden Canoes

    Initially I was going to do that, keeping the old pieces as patterns. I wasn't clear enough in my initial post that I came to think I could improve things by eliminating the small filler pieces that taper to a sharp point along the gunwale (see photo), where the pointed tip is difficult to nail, and also gets stapled into when the canvas goes on, which risks splitting. Maybe that is standard practice--this is the only canoe I've ever worked on--but I was looking for a way it could be done better. I might add that I am a little surprised at some other bits of pretty sloppy work at the factory (I am improving or replacing those where I can) and I wonder if the pointy filler pieces are an example of that inferior quality. I have read elsewhere on the forum that Chestnut quality did decline near the end (this canoe was bought new in early 1972).
  12. Just1moredave

    Just1moredave Curious about Wooden Canoes

    I did my own science experiment like I mentioned in post #6. I measured the width of a dry cutoff plank, soaked it in water for a day, then measured it again. It expanded exactly the amount an edgegrain piece should expand radially, 2.4%. That should allow you to predict the required planking gap.
  13. OP
    Bruce Whittington

    Bruce Whittington Curious about Wooden Canoes

    Thanks for sharing your observation, which is very helpful. In my case I have proceeded with a set of compromise solutions, mostly involving narrower and/or shorter planks. I kept running into problems originating in the way it was built in the factory. For example, on one side, the gore planks ended more than two inches lower at one end, i.e. further below the gunwale, than at the other end (distance from the centre, or the ends of the canoe was equal). That meant a sheer plank of about three inches at one end, and over five at the other. So I took some more of the original apart and replaced it in a more balanced way so I could move ahead in a more straightforward way. I do have a few small planks that are as much as five inches at one end though, and your observation helps me to feel more certain that they will be okay.

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