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PostPosted: August 10th, 2005, 7:02 pm 
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If you're following Vaclav's advice you're on the right track..... he's VERY knowledgeable and won't recommend anything without knowing everything about it first. If he likes the Raka you've made a good choice.

On the cloth....... most glass fabric (hybrid or S/E) will be woven either on a 0/90 axis or on a bias axis (45/45).

What I was trying to explain is that if you are running the entire length of the boat with a 0/90 you'll add stiffness and strength if you can run material on a 45/45 so in effect you end up with material running on all 4 axis along the boats length.........
If you can add a 45/45 hybrid to a 0/90 hybrid you'll get a VERY strong laminate and it will be counter linear torque better along the boats length. If you've yet to purchase material you could inquire if the 45/45 is available and order a 30" wide long enough for the waterline (football), save you a bit.

You'll have some off-cuts that you can use in the bow and stern when you pop it off the mold.


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PostPosted: August 10th, 2005, 8:23 pm 
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Location: Saginaw, Michigan, USA
This is the type of cloth of which I was thinking (one like the first fabric on the page). I may not use this vender, however, I figured other vender’s hybrid fabric would be similar.
http://www.shopmaninc.com/hybrids.html

If I were to purchase the same fabric for both layers one running bow to stern the other layer port to starboard (in direction not necessary extending to either gunwale) would this do what you are talking about? The width of the port to starboard layer does not matter since a more narrow fabric would just mean it takes more strips to reach from bow to stern.
The pattern would be something like this.
Layer 1:= = = = = = Bow to stern
Layer 2:| | | | | | | | | | Port to Starboard
Thus the second layer is perpendicular to the first (or rotated 90 degreees)


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PostPosted: August 10th, 2005, 8:32 pm 
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The fabric you linked to is a 2x2 twill weave...II - - II - - II etc.

What I meant by a 45/45 bias is this... / \ / \ / \ / \

so together you get...... II / \ - - II / \ -- .............. :lol: :lol:

Clear as mud ???


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PostPosted: August 10th, 2005, 8:38 pm 
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Joined: July 12th, 2005, 7:46 pm
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Location: Saginaw, Michigan, USA
I have not found any hybrid fabric that is not a twill except that near the bottom of the above vender and that is not even 5.5 0z.. If I understand rotating the twill fabric for example would not help?

I guess I just do not understand enough about the fabrics; maybe I should dump the idea or just go with the Kevlar as in the book. I only have $201 US into the project.


Last edited by deleteriousone on August 10th, 2005, 8:42 pm, edited 1 time in total.

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PostPosted: August 10th, 2005, 8:42 pm 
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On the top of the page of the link you sent you'll notice a heading, "Specialty Fabrics" it mentions bi-axials. Take a look at the pic's of the fabric and you'll get the picture..... :wink:

Even if you can't find the hybrid in bi-axial you should be able to get it in S glass which would also add a lot of extra stiffness to the boat without adding extra weight..


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PostPosted: August 10th, 2005, 8:49 pm 
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Location: Saginaw, Michigan, USA
Okay,
I see the difference in the +/- 45 degree and the +/-90 degree. I have not found any carbon/kevlar with this type of orientation. This vender does not say if it is seem to have even s-glass in such a layout.


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PostPosted: August 10th, 2005, 8:55 pm 
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Location: Saginaw, Michigan, USA
Just to be clear. Would rotating the twill fabric give any benefit or is adding the extra layer just more weight and money? Obviously it would not be the same as using +/- 45 degree and +/-90 degree fabrics if I understand correctly


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 Post subject:
PostPosted: August 10th, 2005, 9:05 pm 
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Hi again, rotating the twill would only turn the weave and simply give you another layer at 0/90 unless you were to lay it on a diagonal. The idea is to add some diagonal strength with the bi-axial and even E-glass will accomplish this although not as strong as S glass.

If you were to do the waterline (football) with the twill as well as a complete layer of twill stem to stern off set with bi-axial will get the strongest laminate because you will have fiber running in all directions.

Even with a twill if it is folded along it's length is reduced to the strength of 1/2 the weave. i.e. / 0/90 folded along one axis means there will only be 1/2 of the weave functioning along the fold.

Got to run to a meeting. I'll log in later and see if there are any questions I may be able to help with.


Cheers,


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 Post subject: Raka
PostPosted: August 10th, 2005, 10:18 pm 
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Location: Grand Marais, MN
For what it's worth, I've used RAKA on 5 boats now and a couple of paddles. It seems to have held up well and was easy to work with. I used 350/127, I believe, and I will be using it on the kayak I'm currently building. I just ripped the strips today.


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 Post subject:
PostPosted: August 10th, 2005, 10:44 pm 
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Location: Saginaw, Michigan, USA
Komatiq wrote:
Hi again, rotating the twill would only turn the weave and simply give you another layer at 0/90 unless you were to lay it on a diagonal.

Thank you for being patient with a newbie.
Given the above statement if I were to rotate the second layer on the waterline at a 45 instead of the 90 degree angle this would accomplish the task - or - does the fact that it is a twill negate the effect.
If so why even make a twill fabric?
Would a plain weave fabric". . . combining 3K-Carbon(Warp Direction) and Kevlar(Fill Direction) . . .” be better?

Bryan Hansel wrote:
For what it's worth, I've used RAKA on 5 boats now and a couple of paddles. It seems to have held up well and was easy to work with. I used 350/127, I believe, and I will be using it on the kayak I'm currently building. I just ripped the strips today.

Thank you for your reply.
I am glad to hear someone has experience with Raka. I am further glad to hear it is easy to work with, as I need an epoxy which is a bit forgiving. I was thinking that if I have enough scraps of whichever cloth I use I might try to make a couple paddles as well since the materials will have already been purchased.


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PostPosted: August 10th, 2005, 11:50 pm 
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No problem on helping out, in fact I'm glad to offer what I can.

Twill is made to lessen the number of strand overlaps and give more surface area between the overlaps. With normal weave each strand along the 0 axis is crossed with a strand along the 90 axis. You therefore have the "one-over, one-under laminate structure of typical weaving. With twill you have "two-over, two-under" so it doubles the strands between overlaps.
The weakest link in typical weave is the point that one strand crosses the other and it's normally here where the laminate will fail first on impact. Twill spreads the impact over a slightly larger area yet maintains the strand count of the fabric.

Hope that isn't too complicated.......... :oops:

If you do lay a waterline shape in on a diagonal to the hull laminate you will gain strength across all the axis of the laminate. Helps stiffen the boat a LOT.

To gain the strength and thickness you would be better to use the twill hybrid and run the diagonal in the waterline area. That means you may have to butt the diagonal strips to manage the length so keep in mind that an overlap would be best rather than just butting the pieces.

I'll look trough some of the references I have and see if I can find you the 45/45 in C/K and get back to you with any results.



Cheers,


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 Post subject:
PostPosted: August 11th, 2005, 12:50 am 
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Location: Saginaw, Michigan, USA
*** Warning **** long post
You are very generous with your knowledge and it is appreciated. I hope that others can use this tread to their advantage as well.

I Think I got it the gist of this Biaxial thing.
Please correct me if I am mistaken.
Bi = 2 (two layers) stitched together not woven
So a biaxial +/- 45 is a two layer cloth like this:
layer 1 with a strand direction: //////////
layer 2 with a strand direction: \\\\\\\\\\
thus giving you XXXXX as a the fabric.

So a biaxial 0 / 90 is a two layer cloth like this:
layer 1 with a strand direction: _ _ _ _ _ _
layer 2 with a strand direction : | | | | | |
thus giving you ++++++ as the fabric.

I guess you could have a tri or quad axial fabric as well if you used 3 or four layers of cloth (0/+45/-45 , 0/+90/+45/-45). Cloth would not be the correct term since it implies woven strands.
Therefore a plain weave would be a 0 / 90 biaxial using two material (one for 0 degrees and the other for 90 degrees) except for the fact that it is a woven not a stitched and layered cloth.

I am still unclear where a twill weave would fit into the picture.

In theory a stitched strand fabric should be stronger than any woven fabric do to the slight bends in any given material needed to interlace the weave. This brings up the following questions (which you need not answer)
If this is true why have any woven cloth at all?
Would a twill weave be inferior to a plain weave?
edit ** I see now you answered about that it would be just the opposite, I started to compose this reply before you made the previous post.

Given theses assumptions my canoe might best be constructed thus:
Hybrid inner layer bow to stern
Hybrid football layer at a 45 diagonal (port to stern) to inner layer.
Biaxial 0 / 90 S-Glass bow to stern on each side overlapping on the keel.
A biaxial +/- 45 S-Glass bow to stern over the keel covering the side 0 / 90 biaxial cloths

The none of the biaxial fabrics I have found are billed as Kevlar, Carbon, Hybrid, E-Glass or S-Glass. They are just X oz. with or without mat. Why you would want it matted I have yet to figure out unless the mat is just to hold the strands in place better than the stitching alone.

That smoke you smell in just some neurons frying. :o If I could only program a canoe into existence, I fear my PC is just not powerful enough.


Last edited by deleteriousone on August 11th, 2005, 1:24 am, edited 2 times in total.

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 Post subject:
PostPosted: August 11th, 2005, 1:20 am 
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Quote:
Given theses assumptions my canoe might best be constructed thus:
Sounds like you are on to it now, that laminate schedule would be the strongest option.

They do have tri's and quad's already, good call to see the potential. Here's a link to a leading laminate manufacturer just for your reference.
http://www.vectorply.com/default.asp
We use their product a LOT because they will custom weave just about anything we can suggest and their infusion specific laminates work well for the large infusion projects we work with doing yachts.

As you realized stitched material is stronger becasue there is no overlapping of the strands but it's more expensive to produce. Strange as it may sound the machines used to weave are far simpler than those required for stitching.

Twill is a stronger version of a standard weave and would work very well for what you are doing.


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 Post subject:
PostPosted: August 11th, 2005, 1:27 am 
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Location: Saginaw, Michigan, USA
Will wonders never cease, I understood a concept.
Thanks for the vender tip, I will check them out.

Komatiq wrote:
That means you may have to butt the diagonal strips to manage the length so keep in mind that an overlap would be best rather than just butting the pieces.

Would not overlapping the diagonal instead of butting the sides of the strips give me a washboard effect down the hull? I understand it would be stronger since where the strips butt together would be a weak spot (a fault line if you will), however I would think that overlapping would give me a 'hilly’ hull with each layer of S-glass accentuating the effect


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PostPosted: August 11th, 2005, 1:39 am 
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Yes it would tend to give a raised edge which is why I suggested the 45/45 axis material to accomplish the diagonal stiffener.

If you haven't purchased the materials yet it may be worth the effort to try and source some 45/45 even in S glass as that would add a lot of strength. You could then do the twill in the 2 alternating layers and end up with a strong boat and still be light.

This thread got me thinking because I've wanted to build another stripper for some time now but also wanted to use some C/K that was custom woven for me some time ago. I'm thinking I'll do 2 boats, one strip and the other a super light hybrid using the stripper as the mold.

Thanks for starting the thread, now there is smoke on this end as well..... :lol:


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