bamboo spar

[Carlos Estevez]

Hi all
Please be patient with me, english is my third lenguage.
I have my boat´s foresail gaff broken.
She is a schooner made in Belgium in 1947 and I use to take passengers around Bombinhas, Santa Catarina state, south of Brazil.
Actually I have no time nor disposition to glue light wood planks together, wait to cure, round it, sanding, etc, mainly because we are starting the summer season in southern hemysphere.
So I went to Porto Belo, and cut a couple of bambú açú (big bamboo) but it is not straight enough.
Please would you mind telling me how to unbent the spars?
As far as I know, some bamboo furniture makers used to apply heat with a torch wich makes certain sorts of bamboo to be bent easily, like a thermoplastic pvc pipe. Can I use the same procedure?
I have alredy seen Craig O´Donnel´s cheap pages and several others but I couldn´t find an answer.
Fair Winds and merry Christmas for everybody!

[Donn]

An electric heat gun will probably work. All you want is enough heat to soften the lignin in which the bamboo fibers are embedded. Apply the heat evenly along the length to be bent, taking care not to discolor it (too much heat). Have a bending jig already assembled before you heat the 'boo. Let it cool in the jig, and it should stay where you want it.

[Old Bingey]

Bamboo bends wonderfully when heated. I think you could use any method to heat it but the traditional way is to do it in a fire. Professional fishing pole people use a long pipe with holes drilled all along with an LP gas/air mixture flowing inside to make a flame at each hole. They rotate the bamboo in the the flames by hand until it gets shiny and dark from the caramelization of the sugar in the wood. That process not only allows them to straighten the poles by eye but seasons the bamboo immediately. There is sort of an art to it. I heard that you could do the same thing with a long fire built of straw or leaves. Anyway, hot, green bamboo gets as limp as anything. The boiled PVC pipe analogy is accurate. I know you have seen those bamboo walking sticks with the handle bent in an almost complete circle less than six inches diameter.

[Bob Cleek]

While bamboo has been used for spars for centuries in the Far East, finding straight pieces may be a problem. Why not consider a similarly sized piece of PVC pipe until you have time to make a new spar?

[Lucky Luke]

Hi Carlos
Bamboo makes nice ligth, stiff and rot resistant spars. However, you will find difficult to attach fittings. The big hollow "female" bamboo is better for that purpose than the strong, smaller in diameter, "male" bamboo, used only for battens.
Straightening them is no problem with fire, which is done here commonly, but that leaves an unpleasant blackening on the bamboo. A hot air blower like Donn suggested is probably best, although I don't know if you will find one delivering enough heat. One necassary precaution is to drill a small hole in each section (chamber?)of the bamboo to prevent it from cracking - which it will to anyway after some time.
Bob's suggestion of using PVC pipes is not good since they are not resistant/ rigid enough - by far.
What I would recommend, however, would be to use some of the nice, light pines you have in Brazil - a solid piece I mean - easy to shape approximately enough if you have no time, and far easier to put the fittings on it....
Have some nice sailing with your "Belgium-Brazilian-bamboo-sparred-gaff-schooner" tongue.gif

[ 12-25-2004, 01:51 AM: Message edited by: Lucky Luke ]

[Carlos Estevez]

Thank you all guys for your points of view.

We have here in Brazil only fast growing pine trees resulting in a light but soft, low density wood.
Also it is hard to find solid poles. All you can get easily are 3 meter long planks that you have to glue together to create a solid piece, then you need to fair the edges and round it.
And worst of all, it is not dry wood, so you have to wait for it to dry or take it to the oven.

In 2000 I tried a slightly better kind of pine named araucaria. Araucaria pines grow in the intermediate plateaus of Paraná state, where the winter season makes a little more dense wood.
The pieces I used lasted 3 years, some others 4 years before falling apart.
Fortunately, the masts and the booms still are original Riga pine from the Baltic regions and are in good shape.

Well, I took my bamboo and switched on a small heater with a built-in fan blower and made a chamber around the spar of several layers of newspapers. After four hours of heat and jig force, all I get was a lighter green area and the same sine form of the bamboo.

So I decided to try to make the curvature work for me in such a way that when I haul the peak halyard, it will (hopefully) pull hard against the wave unbending the spar.

Fixing the gaff fittings was not so awful as they are made of galvanized iron. Some wedges of hard wood and a big hammer where enough to open it up, then it was a simple matter of sliding it in place and close it with c clamps to cope with the bamboo´s circumference, and tighten the screws.
It looks now like a pretty weird gaff, but I think it will do.
Fair winds
Carlos

[Chayco]

Not familiar with bamboo in Brazil, but in Southeast Asia there is a bamboo that is solid.
The Thais refer to it as 'mai pai'.Very strong,commonly used as tool handles. It does get large (mast potential). Might be worthwhile knowing if similar grows in Brazil.

regards...Ken

[Carlos Estevez]

Hi guys, my bamboo gaff was tested today and it worked pretty good. I am happy and I expect a gaff life of at least three months. I am affraid the bamboo will rip along at some extent as it dryes under a sun that shines with all it might, but I will keep the whole pack serving a tight worming around the spar when needed. Tourists may think it is simply fancy work.
Ken, I never heard before about solid bamboo here in Brazil so I will take a look at it.
Cheers
Carlos