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Old 30th January 2008, 04:54 AM   #21
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Poster #20, I'm not sure you got the distinction. One claim is that faster "reflex speed" is due to lower weight primarily. Another claim is that is is properties of the carbon fiber itself that causes the faster reflex.

Under the first clam (which is what I believe in): if you build one mast in 100% carbon fiber and another one with identical weight and stiffness using less carbon and more glass, they will have virtually the same reflex speed (and if you compare say a 55% standard diameter freeride mast with a 100% rdm wave mast you in could in practice come out with rather similar stiffness and weight data).

People that believe in the second claim will think that the 100% carbon mast will have a faster flex response in this case.
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Old 30th January 2008, 06:08 AM   #22
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Hi Ola_H,

It's my thought that comparing SDM masts with RDMs might be taking certain liberties on the scheme of things, regardless of differing carbon contents. As I'm sure that you're aware, different sail designers taylor their designs around different diameter mast types, and that doesn't even begin to address preferred bend curves.

To be fair in a broad sense, I'm inclined to think that comparing SDMs to SDMs and RDMs to RDMs makes for more sound comparative data. I still have an interest in SDMs (with different masts of carbon fiber contents), and I know without a doubt, that much thought considered right is truly subjective in nature, especially considering varying sailing interests and respective design formats.

If one starts contrasting apples with oranges, its my thought that things ultimately have to get much more complex when considering different disciplines and preferences out there.

Last edited by steveC; 30th January 2008 at 11:51 PM.
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Old 30th January 2008, 12:33 PM   #23
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The SDM/RDM thing was just to indicate that it _could_ be possible to build masts with different materials but similar weigh properties, not meant to be a real basis for comparison.

In practice it is of course impossible o build on glass mast and one carbon mast and have both weight, stiffness and geometry identical (since carbon is stiffer in the same weight).

The argument from the start is that it is the is is the weight difference that is responsible for the reflex difference, not the the material choice per se. In theory this is a clear distinction, but in practice the two effects get kind of hard to isolate (and keeping everything except geometry the same is probably the closest you gonna get towards isolating material choice).
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Old 30th January 2008, 04:10 PM   #24
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Posts: 459
Default Hysterisis ??

Hope you havent got it ?? (Hysterisis)
Anyway ; it was me that mentioned it and I agree I dont think it has any real effects in this case.Inernal damping differences between C and glass will be tiny. ( I would imagine)

I cant see how it woul be possible to build two masts of equal stiffness; equal weight ; one of 100%C and other 50% C (yet same reflex ???)

Lighter masts of equal stiffnes must have quicker reflex.
The equal weight lower carbon would be softer.

I just think for sails under around 8 metre 100% masts are too stiff (Unless they are RDM)
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