Strengh of 24 oz woven vs 15.2 oz Bi-axe

Hi

Does some body can inform me if 24 oz woven roving in epoxy is stronger of 15.2 oz 0-90 Bi-axe in epoxy too ?

I can have a roll of 24 oz woven roving at very low cost.

 

The roving should be stronger, but do not forget to account for the extra weight/cost of the extra epoxy you will need to wet out the roving.

My guess is that it will take about 3/4 pound more in epoxy per square yard. With epoxy at say $58 you spend more than $4 a square yard more to wet out that "cheaper" material - not to mention the boat now weighs more than it needs to. Very rough math done in my head, so it could be off - but even if its far off, you see the point

 

the cloths you're comparing have 60% weight difference,,but with the better engineering of biax ,I'll think the 2 cloths are pretty comparable in their strengths............PLUS the weave in the roving also absorbs more resin per it's strength,,,,,so I'd say you're quite possibly going to double your resin consumption ,,price of resin,,,AND weight.,for the same strength.

.......a good supplier will be able to specify what biax would compare with the roving.

 

Jean-Francois,

If the two fabrics are made with the same type of glass, the tensile strength is proportional to the weight of the fabric. However, if you pull an individual strand of glass from the edge of a roving fabric, you'll see that it has little wiggles from being woven. But, if you pull a strand from a biax fabric, you'll find that it is straight.

That difference has two effects. The roving will be less stiff, because when you put a load on it, the fibers tries to straighten out first before they begin to stretch. And, because of the roving being woven, the fibers aren't as efficiently packed together as in the biax, and consequently it ends up being thicker and with more resin in it than a layup with the same weight of biax.

This explanation is of course quite simplified, but I don't have all night.

Yoke.

 

Thanks for this topic as it appears I will have to lay up my own 1/4" ply for hull skins to get a thick enough inner and outer skin for sanding, staining and varnishing. 1/8" inner and outer plies with a rigid cloth in between for glueing and puncture resistance to allow enough time to safely abandon ship.

 

What Yoke said. It depends on what you mean by "strength".

 

Tom, tensile strength of dry glass along the fibers. As stated, a very simplified explanation, especially the bit about the roving fibers only straightening before stretching in a laminate, but I hope you get the drift.

Yoke.