Green Bamboo: No Problem?

[PeteCress]

Just found a stand of nice-looking bamboo: straight, tall, some stalks are 2+ inches....

Looks promising for replacing a boom and some pola spars on my canoe.

My knee-jerk reaction is to just cut the stuff and use it green - letting it dry out in use.

Or so I need to let it dry before use?

[Mrleft8]

It crushes very easily in it's green state, but dries very quickly.
If you cut a few canes now, they'll be ready by mid may. Cut them a couple of nodes longer than you want.

[Bobby of Tulsa]

http://www.lewisbamboo.com/moso-bamboo.html I don't know why this doesn't work when I post it.

[ChrisBen]

Bamboo Plants | Lewis Bamboo

[Bobby of Tulsa]

Show off. Thanks.

[PeteCress]

http://www.lewisbamboo.com/moso-bamboo.html I don't know why this doesn't work when I post it.

Rack up one more way this forum is weird.

But I copied the link and pasted it into another browser window and it worked.

Go figure....

Thanks for the link.

[Bobby of Tulsa]

Hope that helps.

[seedy]

http://www.lewisbamboo.com/moso-bamboo.html

[kenjamin]

My experience is that when it's dried out, it's harder, lighter, and takes epoxy better. Sometimes I apply fiberglass sleeves to bamboo to make it stronger and to weather better. It only takes a couple of months to dry out.

[PeteCress]

Sometimes I apply fiberglass sleeves to bamboo to make it stronger and to weather better.

First intended use is to replace the boom on a sunfish-style rig - and I will probably do the fiberglass-re-enforcement thing where the main sheet attaches and where it attaches to the mast. I've got some 1" and 2" tape. How wide would you make the wrapped areas? Or would you do the whole section from joint-to-joint?

Is there anything to be gained by applying spar varnish?

[St.J]

There's a Wharram build and sail blog somewhere that shows fibreglassing over a bamboo spar.
Underneath is a fantastic fungal growth. I'll see if I can find it.
St.J

Here it is:
http://alunaboat.wordpress.com/2011/...te-technology/
Don't know how much you want to trust the science.

[WX]

When it is dry run it over a flame till it sweats, wipe off the sweat and it will look polished. When you cut the stems make sure they are mature as in no younger than two years. The older the better...not dead though.

[kenjamin]

First intended use is to replace the boom on a sunfish-style rig - and I will probably do the fiberglass-re-enforcement thing where the main sheet attaches and where it attaches to the mast. I've got some 1" and 2" tape. How wide would you make the wrapped areas? Or would you do the whole section from joint-to-joint?

Is there anything to be gained by applying spar varnish?

Tape should work but you'll probably want to overlap the edges as you wrap it. I would do the whole piece because it will be much stronger that way but most importantly it will keep the boom from getting that ugly black fungi that bamboo always attracts when it weathers. Spar varnish will provide UV protection for the cured epoxy. It will degrade faster without the UV protection.

I use fiberglass sleeves for my bamboo. A sleeve can be applied to the full length of a piece of bamboo without any overlaps so the layer of fiberglass is smooth and lighter than wrapping with tape. I use a bar-b-que rotissoire meat turner to constantly rotate my bamboo piece as I apply epoxy. This allows me to put on one single thick coat with minimal drips. It works great. Here's some pics:









As you can see, the sleeves also come in hybrid cloth like the above fiberglass/carbon fiber. My source for the sleeves is Soller Composites. I gain nothing by you using them as a supplier.

http://www.solarcomposites.com/

[WX]

Tape should work but you'll probably want to overlap the edges as you wrap it. I would do the whole piece because it will be much stronger that way but most importantly it will keep the boom from getting that ugly black fungi that bamboo always attracts when it weathers. Spar varnish will provide UV protection for the cured epoxy. It will degrade faster without the UV protection.

I use fiberglass sleeves for my bamboo. A sleeve can be applied to the full length of a piece of bamboo without any overlaps so the layer of fiberglass is smooth and lighter than wrapping with tape. I use a bar-b-que rotissoire meat turner to constantly rotate my bamboo piece as I apply epoxy. This allows me to put on one single thick coat with minimal drips. It works great. Here's some pics:









As you can see, the sleeves also come in hybrid cloth like the above fiberglass/carbon fiber. My source for the sleeves is Soller Composites. I gain nothing by you using them as a supplier.

http://www.solarcomposites.com/

Very interesting. I had heard of the sleeves but I had not looked into them...I will now. Thanks.

[PeteCress]

Bump....

viz: http://tinyurl.com/82mo868

This stuff has been stored horizontally on the top rung of my kayak rack for a couple months now.

Ultimate destination: spar replacement on my outrigger canoe, which is currently using a muy expensivo skinny windsurfer mast for the boom.

Looks to me like there's no way I'm using this stuff without some sort of coating/covering as in kBenjamin's FG tubing.

This one was dead when cut, but the others were green when cut and are showing similar splits.

Is this recoverable? i.e. if I coat the bamboo, whether just with resin or with FG tubing is it going tb OK? Or is it a symptom of something deeper?

[Mrleft8]

I'm guessing that the bamboo you cut was this year's growth..... See if you can get some of last year's stalks, and try again. I just burned a bunch of stuff that got knocked over in the storms last year, and it had no splits at all..... In fact even though they were wheat straw colored, and therefore (I assumed) completely dry, they exploded like M-80's when the fire heated them up and the air chambers expanded.....
But yes..... The new stalks will crack badly as they dry if they're new growth.

[PeteCress]

...See if you can get some of last year's stalks, and try again.

Is there a way to visually differentiate this vs last-year's stalks?

[upchurchmr]

The price of the carbon fiber and epoxy would be more than an aluminum tube and weigh less with less assurance of adequate strength.
Somebody show that I am wrong, please.

[JimConlin]

Combining carbon fiber with glass fiber is purely decorative. Glass is stretchier than carbon, so if the carbon and the glass fibers are parallel, the glass will carry no load. A braided sleeve like that is a good way to restrain splitting and buckling, but save a lot of money and don't combine carbon with glass. Double up the glass if you like.

[WX]

Is there a way to visually differentiate this vs last-year's stalks?

The younger the greener and glossier the stem will be. I am assuming you are cutting Phyllastachys aurea running bamboo which is identifiable by a groove just above the Nodes and on the same side as the branchlets. Look for pale green stems that have turned yellow towards the tops, these are usually over two years old. Don't cut dry dead stuff.

[Mrleft8]

Right.... The newer growth will be dark green, and might have a slightly abrasive quality to it.... The year old stuff will be lighter in color, and be harder to the touch... IE: you won't be able to make a mark with your thumbnail, where as with new growth you may be able to leave a small mark with your thumbnail.... This stuff gets really hard...
I'll try to get a picture of both today if I get a chance....

[Thorne]

Most 'boo used for construction is treated by drilling through the center with a LONG bit, then soaked with borax. This keeps it expanding equally and lets moisture out thru the drilled nodes in the culms.

[upchurchmr]

What is the Borax for? Keeping out roaches?
Does the drilling help it dry more evenly? Less splitting?

Most 'boo used for construction is treated by drilling through the center with a LONG bit, then soaked with borax. This keeps it expanding equally and lets moisture out thru the drilled nodes in the culms.

[kenjamin]

Combining carbon fiber with glass fiber is purely decorative. Glass is stretchier than carbon, so if the carbon and the glass fibers are parallel, the glass will carry no load. A braided sleeve like that is a good way to restrain splitting and buckling, but save a lot of money and don't combine carbon with glass. Double up the glass if you like.

What's wrong with decorative? The red and black "decorative" piece in my pictures above is my boomkin for Xena. Years after coating it, it's still going strong and I really like the way it looks. A more efficient use of materials would be to use a single layer of natural (clear) fiberglass so the beauty of the bamboo would show through but I like the color of the red sleeves (also available in a dozen other colors) and the resultant stick is very very strong. Two layers of natural fiberglass sleeves just gives you a cloudy, milky colored stick of irregular shape.

[upchurchmr]

Nothing is wrong with decorative. Just let everybody know that strength/weight or cost reduction is not your goal.

Very, Very Strong is not much of a comparison to an equivilent aluminum or carbon fiber or even a birdsmouth cedar hollow pole (with or without reinforcement).

I've seen a lot of discussion about bamboo, but never a straight comparison to an aluminum pole. Lets say for a given stiffness, whats the weight?

If you just want "character" thats OK also. To each his own.

I actually don't pretend to know the comparison, but would like to see one.

[kenjamin]

I'd like to see a strength comparison too but not enough to go out and buy a carbon fiber or aluminum stick to compare it to. All I know is that bamboo does not do well at all in the marine environment because of black ugly fungi that love bamboo. The decorative sleeves solve the fungi problem and seem to at least triple the strength of the bamboo. I don't know exactly how much stronger it makes bamboo because in six years of composite bamboo use, I've never been able to break any of it. And the sleeves/bamboo combination makes for a very light stick. I'm not trying to sell anything, just relate my experience with it.

[upchurchmr]

Kenjamin,

How big is your stick? How much does it weight? Could you support it at the ends and hang a 10# weight from the center (any weight that gets it to bend would work)? Then if you could get the deflection one of the bright boys could figure out an equivalent stiffness aluminum tube. We would need the distance between the supports. This is all just to get a little information.

[kenjamin]

I'll try to get that done for you in the next few days. I understand your frustration with my vague comments about it's strength. I'll measure the length between supports, diameter, wall thickness, deflection amount for a specific weight and get back with you on that but I'll need a little time to get that done. I'll explain later. Cheers, Kenjamin

[kenjamin]

upchurchmr,

I was up in North Carolina so couldn't make any measurements until I got home. The measurements I made are not terribly accurate but I did the best I could in a reasonable amount of time. The piece I used is my boomkin for Xena, my Caledonia Yawl. It is 6' long and weighs about 2 or 3 lbs. but I didn't have a way of accurately weighing it. The span was 59 inches. I had four 25 lb. lead bricks that I used for the weights and put them in a bucket ( about 4 lbs.) to load the piece. Keep in mind that this piece already has curvature in it and is not curved downward as the result of the weight just its natural curvature. It works well as a boomkin because it curves around the rudder action and gets back near the centerline to control the mizzen.

When I put 50 lbs. of lead in the bucket the piece sagged 1 and 1/4 inches in the middle of the 59 in. span. When I added another 50 lbs. of lead, the piece sagged only another 1/4 of an inch. The bamboo itself was 1 and 3/8 ths of an inch in diameter and has a wall thickness of 3/16 ths of an inch. The sleeve material was about $4 a foot and the bamboo was free. I think the epoxy used was about $7 or $8 dollars worth. So the boomkin cost me about $40 to make. In the last picture, all the weight of the piece is balanced on the side of my little finger. Don't exactly know what that weight is but it isn't much.