bamboo boat, launch their first small test boat a double outrigger

Discussion in 'Multihulls' started by Corley, Dec 8, 2013.

  1. tmark
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    tmark Junior Member

    We use bamboo to build longboards (of the type you surf pavement, not waves). By the time we're finished they are as much glue as they are wood, or more properly, grass.

    From a cost perspective a bamboo core is 10x's that of birch, 5x's that of maple. It's hell on tools and prone to failure without any warning signs. Could be argued that it's more green but the amount of petro-chemicals required to keep it together puts a lie to that pretty quickly. Also, at least locally it's getting harder to source. It used to be a sexy item for cabinets etc but the bloom has left the rose and designers and builders aren't speccing it the way they did five years ago ... thus suppliers aren't restocking.

    The only reason we use it is because the market wants it. Ride profile, material weight, longevity, all can be just as easily engineered out of other materials.

    None of which is to say that bamboo isn't a sustainable crop and shouldn't be explored as a building material ... it's just to say, that as of right now there's a round peg square hole thing going on ...
     
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  2. JosephT
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    JosephT Senior Member

    You've got some good points tmark. Materials that are hard to work with can be expensive. My contact on the paddles builds them by hand using flat bamboo plies and they are light, strong & very durable. He's not applying outrageous amounts of epoxy on them either to keep them strong. No question working with the bamboo flat stock has advantages, but perhaps other uses are not so good.

    A good friend put in bamboo flooring on the main floor of his entire house. It was very solid & durable. It continues to sell well so whoever is making it must be doing something right...and the supply isn't running short by any means.
     
  3. tmark
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    tmark Junior Member

    Should probably say too, that the most interesting research has to do with using bamboo as a structural fabric ... surfboard makers are probably the most progressive in adopting it, but I think I remember something about a 30+ keelboat being constructed from it 3 or 4 years ago ... a search will also bring up ski helmets, skis etc that use woven strands ...

    I can see paddles built from laminated bamboo being light and having a nice feel to them ... does your buddy have anything posted online?
     
  4. JosephT
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    JosephT Senior Member

  5. upchurchmr
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    upchurchmr Senior Member

    You really need to understand some basic enigineering.
    Tubes have lots of good reasons but putting them into tension is not one of them, unless it is used as a wire, then a wire is easier.

    Tubes are great in torsion where they are the most efficient use of the material.

    Tubes work good in bending, but they are not the most efficient - that would be an I beam. A tube in bending has tension away from the bend and compression in the direction of the bend. So the material needs to be relatively good in both tension and compression.

    Tubes also work well in combined bending and torsion.

    Mostly tubes are easy to get in a manufactured form. That is one of the best features.

     
  6. Baltic Bandit

    Baltic Bandit Previous Member

    A tube in bending compression has one side in tension and has the advantage over Ibeams in offaxis loads
     
  7. Baltic Bandit

    Baltic Bandit Previous Member

    Well I use bamboo as a tiller extension for my skiffs. Its light, cheap, and most importantly, if I captsize and break it, it actually continues to work at about 75% efficiency whereas an FG extension doesn't.


    On the "structural fabric" side - I think that's what the Univ in Nantes is trying to do, to come up with a way of turning it int a structural fabric that with the same resin rates as GF, can be used to build a boat.
     
  8. ancient kayaker
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    ancient kayaker aka Terry Haines

    Given the rate at which bamboo grows it would be great news if it could be made into a useful form. I recall the split-cane fishing poles of my youth, priced far beyond my reach these days, but beautiful and incredibly flexible and strong. Given that these were made by hand back in the 19th century, I wonder why it is such a challenge to process bamboo into a functional and cost-effective material.

    The process of manufacturing plywood doesn't look all that easy either at first glance, given bark, knots, variable size and geometry, variations from sapwood to heartwood, the need for careful drying and the challenges of handing fragile veneers but it was done with massive investment in plywood processing machinery. Glass is scarcely the first material that would come to mind as a boat building material either, but it's here. At the very least bamboo may be a source of cheap and readily replaceable fiber for building materials. Edison even managed to make it into a light bulb.

    The biggest problem exploiting it may be difficulties growing it in North America and the location of most sources beyond the political grasp of Westerners. Those who have it seem to find it adequate in its natural form, and by the time that finds its way to us it is ridiculously expensive.

    BTW the claim that "High-quality bamboo is stronger than steel" can be found at Bamboo at Wikipedia though I have some doubts myself.
     
  9. upchurchmr
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    upchurchmr Senior Member

    Bamboo stronger than steel.
    The first reference in Wikipedia is a magazine article. No points for credibility there. The quote refers to toughness, not strength.
    The second reference is supposed to be from some university - not known to me.
    They compare one specific species and size to A37 steel - sorry I can't compare that to anything I know, and there are no indications as to how it was tested - again not good enough to believe.

    It makes a great mantra for true believers.

    Fundamentally there are lots of different tensile strength steels, not just one to compare to.
     

  10. ancient kayaker
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    ancient kayaker aka Terry Haines

    Difficult to get consistent results from searches of bamboo tensile strength but there's no doubt based on several sources it is at least comparable with many grades of steel. On a strength to weight basis it is 1.6x that of tool steel based on http://en.wikipedia.org/wiki/Ultimate_tensile_strength

    I think titanium has it beat though, and I'm sure it doesn't match carbon fiber for strength/weight ratio; cheaper than those though.

    The wiki result was the highest strength value of any source I found in a brief search but not wildly more than other sources. The comparison was not helped by the use of several different units however; if folk aren't going to use internationally agreed metric units why the hell didn't they just stay with imperial ones? But I digress.

    I found tensile strength values about 50% of the wiki values in another source, still very high, possibly lower because of test method, the highest strength outer fibers were removed to improve bonding for the preparation of test pieces.

    Conclusion; this is by a long way the strongest plant material, at least in tension. Of course it is less strong in compression but still respectable. Makes oak and doug fir look rather pathetic . . . if they can find a way of making it economical and available it's going to change some opinions.
     
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