SOF Kayak - sugest some wood please! [how about White Pine?]

hi all.
I'm planning to make a Skin On Frame Kayak for recreational use.
I may not get just the wood that you guys get at your local store, I live in South India, and want to know what kind of wood would be right choice?

Please tell in what terms you people decide the wood? Like - should it be heavy or light weight? grains? knots? what is the criteria that decides the choice?

Why I ask this is because, here I may not get red wood or cedar that you guys get out there, or imported wood does not come in full length while I prefer full length over scarfing or butt join.

And the name varies a lot in local languages, so it is best to tell what specification or the scientific name for the same. I can source the closest match.

I plan to make the kayak with Marine ply cross sections and hence wood is needed for the gunwales and chine stringers only.


Here are a few timber I might get around my place and their density.

1. Aini/Aangili 595 Kg/m3
2. Bean Teak - 675
3. Jack 595
4. Saj/Lauraceae - 880
5. Red Cedar - 450 Kg/m3

How about Rubber-tree wood? It is very light, bends well and looks strong. It is usually used in packings.

I presume the wood has to be moderately strong, moderately packed, least knots or no knots, least or no bent/twisted and light weight.

[WRC] seems to be the best choice for you people, but I do not think I can get the same here, though some imported is available it must be short in length.

I came across the White Pinewood timber an hour before, it looked white/yellow little knots, close grain, light weight (real light) and available. If there is any thought about white pine please leave a message. [Pinewood is used in matchsticks making, packing heavy machinery, automotive loading in trucks[1 ton weights], chalk box making, and a variety of other uses, and some office furniture making, with varnish it looks nice and beautiful].

thanks,
MS

 

White pine is an acceptable boat wood, but like cedar or any soft wood, it is best used for planking rather than framing parts.
Soft woods also can be used for framing (stringers, etc.) in a light carry-type boat, however, although there may be some better choices at slightly greater weight (in the USA, fir might be used).
A skin-on-frame kayak depends almost entirely on the stringers for strength, so it is a good idea to use at least a medium/heavy-weight wood instead of a light wood, since so little wood is used in any case.
It is easier to bend a medium density or high density wood than a low density
to a curve; in other words, the light wood will need to be larger-dimensioned to get the same strength, and larger dimensioned woods won't bend as well as small-dimensioined woods.
What light woods offer is stiffness that either works for or against you depending on how you use it. You may wish for a certain amount of resiliance to allow the boat to bounce off of rocks without cracking a stringer (heavier wood).
Or, you may opt for greater stiffness to allow a reduction in weight at the cost of resiliance.
This all may sound a little confusing, but that's exactly why people buy plans rather than design boats themselves. It takes a lot of experience to have a "feel" for a structure that's light but strong. Stiffness is very important, but so is resiliance. A certain amount of give (resiliance) relative to the ability to resist deformation (stiffness) is a delicate comprimise in a lightweight craft. In a very light craft, that comprimise is a very delicate one.
It takes into account the interaction of every piece in the boat---- frame spacing, material, diagonal stiffness, and on and on. Finally, intended use is considered.
It would be impossible to say, in other words, what wood would be the best for your boat until a well-conceived dimensionally accurate design was presented to someone who knew wood properties very well. Then you would explain the intended use of the boat. At that point, a reasonable analysis of wood species could be done.

 

If it is only for the stringers, say 1.5x2.0 cm, why not bamboo? Light, strong, durable.

 

I was just about to suggest bamboo.

 

Bamboo is fine for some kayaks, but lashing bamboo involves a ready supply of fair or straight pieces and bamboo is limited in terms of how it's used. In other words, pieces are tapered and have nodes at regular intervals.
It's fine for those who are willing to limit their construction method to work within those parameters.
If I were to9 build a skin on frame boat, I might want a more refined frame. Ash would be my choice for framing longitudinals. I've built backpack frames that were nearly indestructible out of lashed ash. The lashings were of cotton twine first submerged in thinned weldwood glue. It dries rock hard and takes varnish well.
White oak would also be a good choice.
Bamboo is very, very stiff, due to its segmented tubular shape. This is good insofar as making a stiff frame goes, but I imagine breakage would be difficult to repair due to the tubular shape. Hardwoods like ash have more give, which allows bending instead of breaking.
So yes, suggest bamboo, recognizing that it isn't for everyone or every boat.

 

Nahh, please Sigurd, Bamboo is´nt the way to go. I would recommend "Paulownia tomentosa or elongata" for planking, it should be available in Indias northern regions. Teak for structure.
Tests by the University of Southern Queensland of Western Red Cedar and Paulownia showed that Paulownia had better compression and shear qualities. When this is coupled with the comparative density at 11% moisture of 275Kg/m3 for Paulownia and 450Kg/m3 for Western Red Cedar it makes Paulownia lighter but stronger.
DENSITY 10% MC (moisture content)
Elongata 17.91 pcf
N.W Cedar 18.65 pcf

SPECIFIC GRAVITY 10% MC
Elongata 0.265
N.W Cedar 0.29

SHRINKAGE COEFFICIENT % (Green to oven dry)
Specific Gravity ....... Radial ....... Tangential
Elongata 0.21-0.27....... 1.1-2.0....... 2.1-3.5
N.W Cedar 0.31 ........... 2.2 .............. 4.9

BENDING PROPERTIES AT 12% MC
MOR (Modulus of Rupture) MOE (Modulus of Elasticity)
MOR PSI ....... MOE X 10 PSI
Elongata 5740 ....... 0.858
N.W Cedar 6530 ....... 0.798

Regards
Richard

 

why not? I agree with alan it can be difficult to repair. but easy to replace? A lot of it in india.
Where are you 10^6words? I was in the national parks in kerala and tamil nadu. plenty bamboo for the elephants there.
In kerala I made a backpack from flame bent cane when the other was stolen. Don't use this, it will be soft when wet
Bamboo nodes can be carefully shaved but I don't know where it will break then. It usually splits between nodes if bent too much.

keep in mind there is not a question of planking only frame.

thanks for the palouwnia data. wish i could find here.

 

Thanks Sigurd..... jah, the ability to read is a godsend.........

DONT USE PAULOWNIA FOR FRAMING!

Go for SAJ then, is widely available in India, but have a look at the density!!! There are (over 300) some very light species of the cinnamon sort sold as SAJ too. Measure a bundle of planks, weigh them, calculate density. Down to 730 / 750 is acceptable. Watch for oil! Some species are rather oily, does´nt go with resin! Wipe the surface with a white cloth soaked in alcohol, let the cloth dry, you´ll see the oil! (or better not).
If "Mangifera caesia" is available in Chennai (should be) you have no oil issue, but a little less strength, doe´nt matter that much if you laminate cos it´s easier to work, but Saj is the better choice.

Regards
Richard

 

Where can I find your wood data base, Apex1?

 

At my office, right hand side, first cabinet, top shelve! Put the files and books back in place please!!!

Regards
Richard

 

Thanks! Your xerox machine stopped working, it ran out of paper so I gave it some bamboo fibers???

 

B A M B O O - WOW check my other thread in the past few months, Half way through building a complete Bamboo frame with hemp string lashing only! [A Johansen Replica?] http://www.boatdesign.net/forums/st...der-13-feet-stability-25323-6.html#post258256

Now I want to make a complete wood kayak, and not use any bamboo in this!
I might make a composite Ply frame-Bamboo longitudinals later, but now I want to make it in wood!

Thanks for the Bamboo idea though, I love to work with Bamboo!

 

aha. bamboo I think is no good with ply or wood skin because it can only be round - unles you split it for chine logs and then you need a very good bond tecnique because of the small contact area.
Then probably what Apex1 said, but also look up ancient kayaker's thread about wood for chine logs.

 

I get to see some used Pinewood Logs 20 to 21 feet long, which has been used to pack machinery, so there are minor nail holes in them every 4 inch or so. Would this do good? an i pack the nail holes with some sort of packing, and not worry about it and still use it?

It will be cheap and half the price of fresh timber. I get it in plenty and can make mistakes with it, not have the guilt of wasting nice timber. What do you people think?

 

cool. holes are no problem. pitch, epoxy, other glues... you probably already know of the stitched wood boats in kerala.
One of my threads are discussing making a kayak using this technique.
I don't know pinewood though.