bamboo planks

[adriano]

does anybody have experience in using bamboo strips for strip planking/epoxy
construction? Apart from being eco-friendly and low cost, expecially the "Moso" species seems to have exellent mechanical properties!
Does anybody knows advantages and disadvantages by using solid bamboo planks
in boat strip/epoxy construction?
Thanks in advance for any suggestion.
Adriano

[Hullaby]

You need to completly remove the outer skin as this stuff is like mold release!
However, whatever species you use the fiber density is best right next to that skin....so don't shave off a 1/4 inch trying to get flat strips...in fact, I would go against the natural inclinanation to put the curved side out when stripping. The inside of the culm is much softer and lower fiber density( easier to shape.). You can readily see this by closely viewing the end cut. Narrowplanks would also be good so you do'nt have to shape too much fiber off.
Very important: Bamboo has very little cross grain. You must provide a good cross grain for it. That means a directional glass layer on both sides of the stripping.
Finally Bamboo has a very high strength to weight( pound for pound stronger than steel in tension!) but it's pretty dense. So I think it would be very easy to over spec the core thickness and end up with a very heavy vessel.
Plan on lots of labor

[PAR]

Bamboo would make a pretty poor strip plank core material, for several reasons.

Originally Posted by PAR

Bamboo would make a pretty poor strip plank core material, for several reasons.

That was the nice reply, now comes the truth:
hands off! It is just not possible to use Bamboo in modern boatbuilding methods! (well, except you are willing to spend twice the money and labour you would need for a full carbon Epoxy boat)
When you search the Forum you probably find other opinions on that topic. And probably my final description, why not, too.

Richard

[adriano]

Thanks,
For sure more labor is involved in. Anyhow in my case labor cost is not a big headache.
I am assuming that you get short lengths bomboo planned planks (rectangular shape) since the thikness is decreasing with the height of the culm. In order to avoid too many joints I am thinking that we can laminate two bamboo planks together by the opposite ends (root side versus higher culm part) and by the planned skin side, in order to get more uniformity, then plan it to the desired thikness. I am looking to get laminated final plank dimentions at least of 15/18 mm. high, 30/35 mm wide (cove/convex) and 4 mt long to be joined together to achieve any desired length.
Apart from the labor intensive job, do you think there would be any major technical disadvantages in using such laminated planks as first skin of trip planking combined with a core of two layers red cedar veneer 6 mm. or 3 layers of 3 mm. with light fiber glass woven mats as final layer? Thinking here about 45 ft sail boat hull
I do believe that we can achieve somehow a lighter/stronger boat and cheaper in regards of material by replacing solid wood strips with an eco-friendly material?!
Thanks for any further comments
Adriano

[Hullaby]

Yikes!!
I thought you were talking about something fun and small....Kayak maybe.
Not a good idea. I agree with the others. Bamboo probably doesn't make sense at that size. The glue weight alone with your multiple cores and lams isgonna make it a beast.
And while your labor may be free....Just creating all the bamboo lumber you describe will be more work than building a composite hull..

Originally Posted by adriano

I do believe that we can achieve somehow a lighter/stronger boat and cheaper in regards of material by replacing solid wood strips with an eco-friendly material?!
Thanks for any further comments
Adriano

Definitely not! Neither cheap, nor eco friendly! And surely not sensible. As I mentioned, search the forum, do some legwork yourself. I elaborated somewhere on cutting off the humps, damping the stuff, pressing it, to get flat, glueing the insides together to get a sort of "sandwich" plank, and so on and on. At the end your eco balance is worse than carbon fibre and your cost is above of that. Do you see any advantage?

Richard

[adriano]

Well,
It sounds like you do not have much direct experienses with this material, nevertheless pls let me say this:
I do agree that such amount of extra job is frightening anybody despite lot of work is being done by existing simple machines for bamboo planks like splitting, planning, shaping etc., but once the labor factor (it doesn't need to be free) is not really a main issue I do not agree further!
Frankly when I was told for the first time about bamboo properties I was thinking of a conoe too. Believe or not, recently when reading a report on special magazine, reporting that a large modern sail yacht has benn successfully manufactured in Italy by using bamboo!, I made up my mind to further inquire on this subject. The way they use it somehow has been kept secrect, this is the key!
For sure I do not agree that bamboo material is not eco-friendly!
It's fast growing fibrous plant available in abundance on earth and supposed to be one of strongest building materials ( at least compared with any solid wood which may be used for epoxy strip planking) I am considering here the giant species which reach 30 mts and whose diamentions and wall thikness is suitable for the specific topic. It has extraordinary mechanical and physico-chemical properties!
Reports say: "THE CELLULOSE FIBERS CAN BE COMPARED WITH THE REINFORCING FIBERS IN AN ADVANCED CARBON/EPOXY COMPOSITE WHEREAS THE SURROUNDING LIGNIN CAN BE COMPARED WITH THE EPOXY MATRIX"
You may believe or not this is up to you!
I do not agree that epoxy laminated materials would make in this case (at least I understand like this)the boat heavier. There is no question that the machanical properties of a laminated material in place of a solid piece are far better and makes it lighter(ther shouldn't be a need to get deeper into the matter!)
By the way before you get a carbon fiber boat more eco-friendly and more cost accessable there is a long way to go! just think about the energy required to achieve the carbon stage! Do not think only about yr efforts on the boat premises!
I am of the opinion that nothing in life is served to you on "a golden plate"I mean with this that everyone has to sqeeze his own brain to achieve a goal/success!
Obviousely some kind of interest should be there to support the final goal which makes a lot of difference.
Personally I still believe that this material could have big potential and is worth to be further taken into consideration.
Hope haven't been boring you too much.
Thanks
Adriano

[Hullaby]

Is there a good, already invented, acronym for " One who posts queries he already feels he has all the answers for and ......"
Ah, nevermind. I'm done with this one.

[adriano]

I do not think it's like that, he rather doesn't give up at the first shot!
Thanks
adriano

[PAR]

Depending on which strip planking method you'd employ, you may gain some of the density disadvantages back, but generally, the material is too dense to be a good choice as a true core in a sandwich composite and has insufficient longitudinal stiffness (compared to other species for it's weight) in a more traditional strip role. If it was the only wood you could get your hands on, you might get favorable results with a Lord method scantling, strip plank build. You could get by with ~50% less core thickness, partly negating the weight penalty, though again, not compared to other species.

Part of the difficulty with bamboo is it's relatively an unknown species and looking up physical properties is difficult, in the traditional sense as it's not a tree, but a weed (actually a grass). Yes, it has some wonderful attributes, but as yet has found limited uses in the marine industry other then cabinets, flooring and trim in yachts.

It may be just a syntax issue, but laminated structures need to be engineered to be lighter then solid limber structures. You're seem to be under the impressions that a laminate is naturally lighter and this couldn't be further from the truth. Typically, a successful laminate combines a light weight core with a fabric sheathing, set in a resin system that closely matches its physical properties (typically elongation). The heavier the core, the more is must offer in the strength and stiffness, to the completed panel or the weight is just a burden the panel must bear, which serves no good.

For most small craft you're going to want strip densities in the 22 to 32 lbs. per cu. ft. range and larger yachts 32 to 46 lbs. per cu. ft. Interestingly enough most that I've read about bamboo compare it to red oak across several categories, but in this regard the density is the real issue and why, there are many alternate core possibilities that are superior.

I think it can be used successfully, but it would need careful engineering or a heavy structure will result.

[adriano]

Hi Par,
Appreciate yr comprehensive comments and for sure from someone who knows the matter better than me!
I may have to mention, to let better understand , that in the country where I have chance to achieve eventually such a “project”, red cedar mainly is available on spot and good quality Epoxy resin with a team of 20 people with over a decade of experience with solid red cedar strip/red cedar veneer and glass woven mat construction. All other high tech materials (for hull construction) are available but imported and at high price. Somehow I have to stick with the traditional wood strip planking/veneer contsruction. So my thought was to replace only the first layer of red cedar strip planks( not for core) both partly on permanent and temporary laminated frames. (sail cruiser)
This not only because of cost factor and environemantal reasons but also because I do not know for how long Red C. will be available there. (some restrictions for woods cutting are already in place) On top of that plenty of bomboo is locally available . Bamboo planks are already on the market but sofar I've seen only in short length.
There are lot of data curried out on bamboo, available even from us -institutions which are very encouraging (may be I am overestimate these?!).
Regarding the lamination I am simply going from the point of view that basicallly you can achieve same or even better mechanical properties with lower volume than the same solid wood you want replace.
The fact that somebody here in Italy has already build a large modern sail yacht with bamboo,
I think my thoughts are not out of this world!?
The key is how to use it in the best suitable way!
Thanks
Adriano

[Luckless]

I'm wondering how bamboo can hold up as thin veneer strips, not structurally strong 'plank' strips as usually found in boat building. Layered in three or four directions in epoxy, kind of like a straight up fiberglass hull, without the fiberglass.

Now, this isn't something you can do alone in a workshop with a few hand tools, but with the correct equipment to process the stuff, you could have a useful and cheap material.


Now, I really don't see how you can call bamboo not eco-friendly compared to other plant products. I'm not sure how yields compare on a per acre at harvest time, but I do know that you have a one or two year growing season for some of the best bamboos, meaning you can keep harvesting the same plot of land year after year, rather than waiting 20-80 years for it to grow again.

Of course, this is assuming it is milled to a usable product near harvest site, rather than shipped as raw bamboo for processing over seas.

adriano It sounds like you do not have much direct experienses with this material,

Be assured mate when it comes to boatbuilding in wood I can compete with your experience. And as a builder I´m always interested in new methods, and know the properties of Bamboo since ages.

However you like to cheat nature, at the end it comes on the table.
Bamboo is NOT as eco friendly as common boatbuilding wood species and not as nice as many like to believe! To get a useable and even quality strip of Bamboo you need a lot of processing. I am not willing to go deeper into that matter here. Do some legwork after removing the pink glasses! Search for the >disadvantages< of Bamboo, not for the well known advantages and you will soon find what I´m talking about. (the inner fibres for example are almost always full of funghi to name just one)

adriano

All other high tech materials (for hull construction) are available but imported and at high price.

In Italy? where do you live?

So my thought was to replace only the first layer of red cedar strip planks( not for core)

Do you know what the strip plank is meant to be???

The fact that somebody here in Italy has already build a large modern sail yacht with bamboo,

That unfortunately is only half of the truth! The boat you mention was built using Bamboo fibres! Thats a completely different world. And the price of those fibres is about the same as the price of a Carbon Kevlar fabric.
Processing the Bamboo fibres is consuming more energy than producing carbon fibre, so where is it eco friendly?

Originally Posted by Hullaby

Is there a good, already invented, acronym for " One who posts queries he already feels he has all the answers for and ......"
Ah, nevermind. I'm done with this one.

Dunno, but what about CUTY ??? Completely Unwilling To Yield

Richard

[Luckless]

I would like to hear the stats on the energy costs in producing carbon fibers vs bamboo fibers. Where are your sources for this?