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How thin could I go..?

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  • How thin could I go..?

    Well, I have the bug to build another board, I have researched Balsa, Cedar and Paulownia until my eyes bled. I really want to build with Balsa and Paulownia but it is so expensive and has to be shipped, which leads me back to Cedar. It is a little heavier but its also a beautiful, inexpensive wood. I also like to buy locally and the hunt for nice wood is fun. I have found 2x6x12 ft cedar to boot, which really makes it attractive because I am building a SUP. My 8 ft board ended up being about 3/16's and with one layer of 4oz, a hot coat and a gloss coat of epoxy, I have to put a lot of pressure on the wood to get it to give even a little. It weighed in at just under 20lbs. If I can keep a SUP under 30lbs I will be fine, even a little over won't hurt me at all. I'm seriously thinking of going to 1/8 and maybe a heavier cloth, maybe 6 oz. I don't see why this wouldn't work. Any thoughts or has anyone tried this? All I have to lose is a broken board, a bunch of time and some epoxy.

  • #2
    No experience but it sounds thin. Maybe if you decrease your rib spacing and glass inside & outside but then you will lose your weight savings.
    But I say try it!
    Kook on a wood board.

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    • #3
      Check out the post of huck, either here or on tree2sea. His idea is using a lot of light ribs and a thin deck to keep weight down. It makes sense because the decks are the majority of a hollow board. As for your particular problem with SUP weight. My second board was a 10'6" paddle board about 30" wide and 4" thick. It had plywood ribs space 12" apart and around 1/4" thick decks. It weighed around 45 lbs after a pretty heavy glass job.

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      • #4
        i sawed the skins for my twinfish 3/16" and after sanding they are thinner than that. made the board very light, my lightest one so far. after a few months and a dozen or so sessions i have started to split the deck where i have hit with my knee or heel. i am going to have to ad another layer of cloth to reinforce. i would keep the skins thicker at least where you are going to stand. or double up the glass. i glassed my board with a single layer 4oz. ribs 8" spacing
        Old enough to know better, young enough to do it anyway.

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        • #5
          I have seen an idea somewhere about using 1-2mm aircraft ply for skin, it bendy and supposed to be super strong but gonna guess it’s a bit expensive

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          • #6
            a layer of glass adds more strength per specific weight than wood, but only to longitudinal forces, tensions. With balsa you need a certain height, but a composite of glass,balsa, glass should be the lightest combination possible, resulting in an H-Beam, where the height of the beam relates directly to strength (if not x² or even x³) If you replace the balsa by cedar, the height will be less at a given weight, which would be a disadvantage.
            It may look nasty, but if you like experiments, the way to compensate could be holes in the cedar, like you do in ribs usually. If you remove half the weight of the cedar plank, by drilling holes or better lasercut a nice pattern you will be able to increase the height of the cedar plank and remaining with the same weight as a lower plank. (For example a 1/8inch or 3mm cedar, may weight 200gr/m² and a 1/4inch or 6mm plank where 50% of the surface is holed, may weight the same) combining this holed wooden plank with an inside glass layer, will be the strongest sandwich achievable.
            The best surfer is the one with the biggest smile on his face...

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            • #7
              Sounds Complicated. I was thinking 3/16cedar which will be less than that by the time I get it sanded flat, then space my ribs 6 inches, double up on the glass where I will be standing. I wouldn't mind going 4 inches between ribs if I could find some light 1/8 plywood. I've seen 3mm paulownia ply on the web but there is nary available down here in Florida. Although, for ribs I could just have it cut down and mailed that way. I like that idea.

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              • #8
                1/8'' or 3mm does not leave much of a glueing surface.
                Kook on a wood board.

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                • #9
                  I've thought about using the the 3mm paulownia ply as an underlayment and then using 1/16'' thick planks on top. Total thickness would be around 3/16''. Might even allow for a bit of heavy exotic woods to be mixed in.
                  There's a company out there that does custom balsa ply but it's very pricey.
                  Kook on a wood board.

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                  • #10
                    This stuff is within easy driving distance in south Florida and looks to be a good wood for the ribs. It wont be as light as Paulownia, but it does come in 3mm. Any thoughts?

                    http://www.worldpanel.com/_p/prd2/11...marine-plywood
                    Last edited by Breadfan; 10-13-2017, 03:35 PM.

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                    • #11
                      Originally posted by kevin keith View Post
                      1/8'' or 3mm does not leave much of a glueing surface.
                      No, it's not much at all!

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                      • #12
                        Originally posted by Breadfan View Post

                        No, it's not much at all!
                        Just glue some strips to your ribs and stringer to make them thicker where the skins will be glued on
                        Old enough to know better, young enough to do it anyway.

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                        • #13
                          I made a set of frames for a 10'6 SUP out of 3 and 4 mm Okoume marine ply. There was only about 300 grams difference. The 3mm is quite flimsy where as the 4mm is much more rigid. I leave 20mm of wood around the lightening holes.I also put stregnthening strips of 4mm ply under where you will stand. I don't think saving 300 grams is worth it. You will save alot more on your skin. Maybe use 6oz on the deck and 4oz under.
                          If you could use some balsa or other wood in none crutial areas it will keep the weight down. You might be able to get model aeroplane balsa. It comes in 1M lengths. I have used this before.

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                          • #14
                            The front part of the deck and a lot of the bottom of this board is model aeroplane balsa. 6mm thick. the deck is glassed inside and out 4oz, the bottom is just 4oz outside. Its about 13kgs for a 12'6 board. Its still going strong years later.

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