Sea Rat

Looking for help chosing the right fiberglass cloth for my project.
I am re-coring a 4ft by 6ft cockpit floor access panel. The plan is to remove the old core, put down one layer of fiberglass cloth, re-core with 3/4" plywood, and then put down two more layers of fiberglass cloth.
My question is which fiberglass cloth should I use (I plan ordering the materials from U.S Composites and also use their vinylester resin). Should I go with a 10oz or 18oz E-Glass, or go with the 1208 or 1708 Knytex Biaxial, or use something different like thier s-glass.

Thanks for the Help

glassdave

iTrader: (1)

the 1708 Nytex is all you need, in most glass shops that fills the bill for about 90% of repairs done.

Sea Rat

Thanks Glassdave, I'll go with the 1708. Just out of curiosity, is there a strength difference between the knitted cloths versus the woven ones (comparing same weight of course)?

glassdave

iTrader: (1)

yes there is, this is just a guess but i would suspect a 1708 would outperform a much heavier roving style fabric quite easily. The benefit of the uni and bi-ax style weave is in that the fibers do lot cross in and over one another and you are able to put the strength exactly where you want it. There is a crimping affect that is present in the heavier standard weaves and most are on a 0 - 90 degree bias which means half of the laminate is not doing much for strength (just along for the ride as a wise man once said ). 45-45 bias 1708 is also much more conformable then any roving by far.

glassdave

iTrader: (1)

one other thing if you are recoring with plywood you may want to cut it into squares about six by six and place them in individually and also use a filler like cabosil to do the edge work and blending of the joints. Two layers of 1708 should work fine.


Have you considered an end grain balsa core like Baltek?

Sea Rat

Thanks for the fiberglass tutorial.
As for using end-grain balsa, the original core was plywood so I assumed it was used for a reason. The panel I'm re-coring is in a high traffic area and where my bolster seats are attached, how would the end-grain balsa compare strength-wise.
As for cutting the plywood into squares, is that for added strength, to contain rot if it develops again, or for some other reason.
I was planning on using West 404 Filler for any edges (also planning on over-drilling, if thats a word, any screw/bolt holes and filling that with filler), mainly because I have some in the garage and I can by the West stuff from my local boatyard.

SUE C Q

S/R the #404 - will be just fine.