Bamboo as mast and spars

Discussion in 'Sailboats' started by mark hannon, Jun 22, 2011.

  1. mark hannon
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    mark hannon Mark Hannon

    Anyone know of a source for bamboo to be used for spars and masts? Up to 18 ft and 3 inch diameter, ect. Thanks, Mark.
     
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  2. Doug Lord
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    Doug Lord Flight Ready

  3. hoytedow
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    hoytedow Old Woodbutcher

  4. CutOnce

    CutOnce Previous Member

    I've used Tonkin construction grade bamboo as spars for my son's boat. It was a low cost design, with a projected life span of three to four years. The spars have held up perfectly. Checking and splitting can and does happen due to humidity changes.

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    CutOnce
     
  5. PAR
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    PAR Yacht Designer/Builder

    Bamboo would seem a terrible choice for spars on all but the smallest boats. Even on these you're paying huge weight penalty for the convenience of using bamboo.
     
  6. CutOnce

    CutOnce Previous Member

    Bamboo as a raw material is quite interesting and strong if processed carefully. The long, well dried fibers are incredibly strong and light in both tension and compression.

    During the build and rigging of my son's little boat, I had to purchase more bamboo than was needed (about 150% more) just to make up the minimum shipment ($35 I think?) required to deal with the vendor. Eric McNicholl, designer of my son's boat was building an excursion/challenge sail boat for a client at the time and he was interested in seeing what could be done with bamboo as a composite component material. Part of his interest was due to bamboo being a sustainable and cheap material - the other was the general satisfaction the bamboo delivered in the children's boat application.

    The client building the excursion/challenge sailboat (I think around 27', cat ketch rigged, open) was willing to try the bamboo composite mast and was so happy with it they built a second. The bamboo was ripped into fibres, assembled on a mandrill and then carbon epoxy wrapped (I could be wrong on details, so Eric should be contacted for accuracy). The resulting spars were light, incredibly strong and made both designer and client happy. They are well into their second season of heavy use with no problems as of my last contact.

    Although no material is perfect, it is kind of nice to find one that can regrow in a year or two. Given the pricing, bamboo as a raw material is dirt cheap.

    I'm not disputing PAR's position that raw, unprocessed bamboo would have many issues if scaled beyond a tiny, cheap and limited lifespan boat, but looking further than just using dried bamboo stalks was an interesting experience with a happy client in this case. I know Eric said they learned a lot about working with bamboo during the process, as it was completely new and foreign material.

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    Bill
     
  7. PAR
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    PAR Yacht Designer/Builder

    Using bamboo as Bill describes it seems reasonable, though I think there are much more cost effective choices then cabrom and bamboo fibers. How about Spectra strands and carbon?

    An 18' by 3" diameter bamboo pole will be quite heavy and fragile.
     
  8. CutOnce

    CutOnce Previous Member

    You'd be surprised how light bamboo is when dried. The Tonkin contruction grade bamboo I purchased is used in many parts of the world as construction scaffolding and (from memory, so could be off) an 18'x3" diameter span would weight around 6-9 pounds dry. Found a distributor here in Canada who brings over containers of bamboo and sells it to garden centers and landscapers as fencing material. Given Eric reduced the material to long 1/8" fibers and got rid of the section barriers, it was pretty light as a core filler.

    Spectra strands certainly would have great strength in tension, but effectively nothing in compression. Would be lighter though, but nowhere as cheap.

    When Eric first said he was going to try this, I thought it was a Kyoto-inspired bong hit thought, but the resulting spar was amazing.

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    CutOnce
     
  9. DESQ
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    DESQ New Member

    There's an ouftit on Lakewood NJ with great variety in bamboo species available; they may ship:

    http://www.bambooandrattan.com/

    I agree that bamboo not terribly suitable for a mast. That said I love it for sprit and boom on my Opti rig and also for boom and yard on my ACA lateen rig.
    Use dowels glued into the ends prior to drilling for outhauls, yard/boom connections, and the like. You can also lash/whip bamboo along its circumference to keep from splitting or binding together where you have splitting. It's amazing stuff. I also split some out with a froe and, after working the staves with thickness planer and crooked knife, use the bamboo for transverse ribs in a skin over frame kayak. They are light and robust. An Umiak with bamboo ribs would be a neat project.
     
  10. Ishmael2702
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    Ishmael2702 New Member

    I have been using bamboo here in Thailand for many years and find it perfect for small boat spars. First drill small a small hole in each section to allow steam to escape, then slowly heat till the color becomes a medium brown. For giant bamboo I use the same technique as for a hollow mast from cedar. Cut in half lengthwise after heating, cut out the baffles between sections, for wiring ducts to be placed, coat the interior with epoxy and re- seal.
    I am Working now on a Proa, that will have free-standing bamboo masts, and have every expectation it will work well.
     
  11. gonzo
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    gonzo Senior Member

    That is the same technique I remember for fishing rods. They last for years without splitting.
     
  12. Squidly-Diddly
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    Squidly-Diddly Senior Member

    I hear it doesn't last too long in marine environment, due to being an over-achieving species of grass rather than a wood, much less a hardwood.

    But I've got faith in chemical preservatives.

    I'd like to see someone combine a cheap, non-toxic chemical treatment of bamboo with shaping bamboo as it grows similar to what the English did for ship lumber, but much much faster than Oak.
     
  13. PAR
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    PAR Yacht Designer/Builder

    You'll still have the weight and node/ring weaknesses to work around. You can mash it flat and make a number of products, like flooring, etc., but a reliable dimensional material, well, good luck with that, as it's been tried for generations with no luck, compared to trees. It's only real advantage is cost, which is typical of 3rd world products. Another major disadvantage is bamboo needs to be pretty highly processed to get some uniformity, say with sheet goods or attempting to make dimensional lumber substitutes. And there's still the weight issue.
     
  14. Ishmael2702
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    Ishmael2702 New Member

    Yes,you must be right. The Pacific Islanders have only used it for spars for their free standing crab claw sailing rigs on ocean capable Prosa for a 1,000 years, maybe some more field testing will work out the bugs.
     

  15. PAR
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    PAR Yacht Designer/Builder

    Low aspect, relatively low load rigs, like those you mention can afford fragile and heavy spars. Plenty of testing on bamboo has been done and this is one of the reasons, you don't see it used in mainstream design and construction. The physical properties of both bamboo and the typical spruces, employed in wooden spar building are well understood and a decided advantage to the spruces is clear, making for the overwhelming majority of spar building choices. I'm glad you like your bamboo, but you're in a small minority, in regard to preference over the more common species choices, in spite of your perceived advantages.
     
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