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  #16  
Old 12-05-2010, 01:29 AM
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On panel stiffness:

If this is what works, I would not worry too much. There is a balance between striving for perfection, and making it commercially viable.

I would say: Get these commercially rolling if you can, even with the "carbon in the middle" layup.
You can always make a new version with improved layup, if your tests prove that a new layup indeed is better (better in stiffness, impact resistance, etc)

And also remember: We are looking at panel stiffness only. There is also overall stiffness. It might well be the case that you need the carbon for overall stiffness (where the panel is in tension) but do not need it for panel stiffness, to keep the panel slightly flexible for impact resistance.

About the 911: My father and uncle have a '73 911RS 2.7 (injection). Quite a beast. However those certain wanted types are expensive. If it is just about the shape, a 912 would be best.
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  #17  
Old 12-05-2010, 08:28 PM
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Thanks again Herman, My comments are in red.

On panel stiffness:

If this is what works, I would not worry too much. There is a balance between striving for perfection, and making it commercially viable.

I would say: Get these commercially rolling if you can, even with the "carbon in the middle" layup.
You can always make a new version with improved layup, if your tests prove that a new layup indeed is better (better in stiffness, impact resistance, etc)

I appreciate your comments. I have been messing with this too long and plan on infusing the next boats with the only three modifications:

1. Using a hybrid carbon/kev reinforcement.
2. Turned the reinforcement 45 degrees to my grid. Do you agree with this idea?
3. Using a silicone vacuum bag

I would like to try using 4oz. (or lighter) biaxial S glass for my 2 outer lams, but I haven’t been able to find a source.

Does anyone have any suggestions?


And also remember: We are looking at panel stiffness only. There is also overall stiffness. It might well be the case that you need the carbon for overall stiffness (where the panel is in tension) but do not need it for panel stiffness, to keep the panel slightly flexible for impact resistance.

One of my test plans is to set up a series of 3 axis accelerometers (probably 6 to 9) to accurately measure hull flexure while the boat is being paddled at full speed, and then repeat the identical test with a few composite racing canoes to learn what I can learn by simple comparison. Do you think that this would be worthwhile? It would at least be a learning experience and fun.


About the 911: My father and uncle have a '73 911RS 2.7 (injection). Quite a beast. However those certain wanted types are expensive. If it is just about the shape, a 912 would be best.

I have attached another photo to better explain where I got the composite 356 idea from. I sold that particular car a few years ago. I still miss it. Your right about the cost benefits of 911 vs. 356, but after looking at this photo again, I think I like the idea of the brite finished comp 356. The 356s nick "Bathtubs” suit them well. All I need is the woody 356 and a clown suit, a big shoes and a large red rubber nose.

Thanks again for your time and advice.

Allan

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Last edited by variverrunner : 12-05-2010 at 08:34 PM. Reason: mi lousy spellling
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  #18  
Old 12-06-2010, 12:47 AM
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Your modifications seem doable. People will still need to convince me on the silicone bag, but do try it.

I have no source for S-glass, it is not popular in Europe.

About testing: You will learn from all testing. So why not?

About 356/911. You might be right. Anyhow, both options are appealing. Subscribe to www.bringatrailer.com newsletter. Bangers in your mailbox every day...
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  #19  
Old 12-06-2010, 11:50 AM
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Here they are in your neck of the woods and sell small quantiles,I used to get Spectra from them years back.

http://sweetcomposites.com/Fiberglass.html
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  #20  
Old 12-06-2010, 03:22 PM
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Herman, Thanks again. The bringyourtrailer site has lots of possiblities


War Hoop, I am looking for 4 oz biaxial S glass. I checked with Sweet Composites and they dont carry it or uni.

Their site does include a nice bit of tech history and nomenclature : fabrics

The link is here

http://sweetcomposites.com/Fabric.html


Allan
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  #21  
Old 12-07-2010, 11:23 AM
idkfa idkfa is offline
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Put me down for a 964
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  #22  
Old 12-07-2010, 11:25 AM
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I do have a 944 on offer.
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  #23  
Old 12-07-2010, 12:10 PM
War Whoop War Whoop is offline
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They have a 4 oz S Glass 24 X 22 Twisted Yarn fabric.
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  #24  
Old 12-07-2010, 07:11 PM
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Thanks War Whoop,

It is my understanding that biaxial is stronger because the fibers are straight instead of woven through. Is that correct? I might try two layers of light Uni S glass at alternating 45 degrees angles, if I can not find 2 or 4 oz. biaxial S glass.

I normally cut my reinforcements in one piece using a template. The biaxial would be way faster to cut and install, instead of a bunch of little pieces.


Allan
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  #25  
Old 12-08-2010, 03:38 AM
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not particularly stronger as it is the same fiber. A bit stiffer because there is no slack in the material, so you only have the elasticity modulus of the material itself. I don't know if you'll notice it with your layup though.
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  #26  
Old 12-08-2010, 09:32 AM
War Whoop War Whoop is offline
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That material is 6 mils thick I doubt there will be any movement,it is not like a 24 oz woven roven
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