: Sam,

: The point I raised, and it is moot because it is proven to be wrong, was that
: it was my understanding that CF had a certain strength per weight ratio
: that favored it to FG. Ted's testing was very useful in that we now know
: that CF and FG of equal fabric weights will not result in equivalent
: weight when epoxy resin is applied (4x the weight is hard to explain
: away). The point I raised was that it may be possible to reduce the weight
: of the CF, by using reduced weighted cloth (which you are indicating may
: not be available, I was only speaking hypothetical, though I thought it
: might come in lighter weights) and still acheived the same strength. Now
: that Ted has posted the numbers, I was wrong, FG is actually stronger,
: which means you can use less FG to get the same strength boat as one made
: from CF, but with a penalty in reduced stiffness.

: However, now we have an interesting set of facts. CF results in a stiffer
: structure, albeit with a penalty in weight and loss of ultimate strength
: and resiliant strength (a term that I am still unfamiliar with). However,
: perhaps for those building a FG boat, they can go lighter on the FG layers
: by using one layer of lightweight CF which would add the stiffness
: allowing a reduction in the amount of FG used. The builder could use a
: weight of FG that will add the strength needed, although it would not have
: provided sufficient stiffness had that weight been used in a FG only boat.
: Whether that kind of construction results in a weight reduction or not, I
: don't know, I'm inclined to believe not.

: Paul

Paul,

You were correct, careful use of carbon fiber can provide strength-to-weight advantages over glass, even S glass. That is one reason CF is used in spite of its cost.

I initially responded to Jay's post by pointing out that 6 oz CF would be heavier than 6 oz glass (at the same fiber volume fraction) to encourage careful thought about concepts that are fundamental to a topic which consistently draws a lot of interest in this forum.

What Ted's sample weights show is that it is possible (I think probable) that woven CF does not "soak up" less resin than woven glass.

Cheers,
Sam