combing different fibers and weights a waste?

[punasurf]

Someone mentioned mixing fiberglass and carbon was not a good idea because the carbon and glass have different failure rates.

 I would love to hear what you people think about this.  I'm thinking about trying some new fabrics but combining with some fiberglass cloth that I already have.

Or should I stick with one type of fabric?  I am leaning toward some carbon/spectra cloth but it is very expensive.  I like strong boards but need to cut down some weight.

Mahalo

[Dwight (DW)]

Taking cues from windsurf construction, the mix of carbon and (kevlar or spectra) is done to survive 20 foot jumps and not snap. Those fabrics also require vacuum bagging. The are unfriendly for hand lamination.

Unless you've been snapping your SUPs, I'd say its not worth the hassle.

I think carbon is insane for stopping heel dents. Use some small carbon patches hidden by the deck pad. Upgrade to S glass and you've got a nice board.

I might go with Vector Net if you've been snapping boards.

[Beasho]

Strong and light = Carbon.

Mixing Carbon and Fiberglass is dicey because of the 'failure rate' you mentioned.  Its actually the modulus of elasticity.  Think of combining a rubber band with aluminum foil in a matrix.  If you pulled the matrix the aluminum skin would bear all the load and break before the rubber band did much of anything. 

Then, without the aluminum foil the material would likely just deform to failure. 

This is what happens with fiberglass and polyester resin.  The resin is stiffer and cracks before the fibers fail leaving spider cracks.  Eventually the fiber, now not supported by resin, fails too.

Epoxy has a modulus closer to fiberglass cloth than the Polyester Resin.  The epoxy stretches more consistently with the cloth which is why it is apparently tougher and doesn't spider crack.

[getsupngo]

I use carbon/Kevlar with S glass on mostly windsurf boards. It does help out with the big jumps and stuff but I primarily apply it to help protect the board from the mast slams. It does that very well in combination with the sandwich.  Sometimes I use it on SUPs, especially if it will also be sailed.  It can be applied without vacuum bagging but it's not as easy as glass. Spectra might need to be bagged on as I hear it really likes to float.  

[punasurf]

Hammertest.mp4

http://www.witchcraft.nu/wave.php#5

You guys might find this interesting.  First link shows a demo of different fibers.  The second link shows the lam schedule of Whitchcraft windsurf boards and has an interesting chart near the bottom.

[getsupngo]

A fiber strand of direct size S glass behaves almost exactly like those of dynema in the video's hand tug test. I've never taken a hammer to it but its some pretty tough stuff too with nice tensile properties.  Much tougher than the regular twisted and washed S glass.  Much cheaper than dynema, carbon, and its fairly easy to work with. Some really sharp scissors helps to cut it.  In fact, just used some DS S glass today under a deck sandwich and its still forming up in the vacuum bag.

 

[punasurf]

Where do you get DS S?  I've never heard of it.

[NLCHAWAII]

Do it . Mix fibers until your heart content , just take notes on what you do for future reference ! Glass when used over carbon can help considerably against dings and impact damage and can also be used as a burn layer or sand layer when sanding . Be fearless and try it . I will say that fibers such as kevlar , dyneema , spectra and other nylon/polyester based fibers are difficult to get a good epoxy to fiber bond . I've tentatively used braided spectra successfully but I've generally had bad results with most fibers that fall in the UHMWPE family .

[getsupngo]

Where do you get DS S?  I've never heard of it.

I got it from a friend a couple of years ago.  I used to get it many years ago from fiberglass supply before it was called fiberglass supply.

Do it . Mix fibers until your heart content , just take notes on what you do for future reference ! Glass when used over carbon can help considerably against dings and impact damage and can also be used as a burn layer or sand layer when sanding . Be fearless and try it . I will say that fibers such as kevlar , dyneema , spectra and other nylon/polyester based fibers are difficult to get a good epoxy to fiber bond . I've tentatively used braided spectra successfully but I've generally had bad results with most fibers that fall in the UHMWPE family .

I've done several boards using 5 oz Kevlar 4HS (285)weave and always happy with the results.
The plain weave 5 oz might be another deal. I've also used 1.7 oz and it's nice and light but so expensive.