Pete,
Thanks, that is a very interesting graph. I'm printing that one out and hanging it over our glassing station. Good for figuring out the potential strength of combinations of layers in different orientations.

I have become a fan of more layers of smaller weave set in different orientations. Then using a bigger fabric. By crossing orientations in multiple layers, it gives strength in broader range of vectored force.

Its been my experience that the part of the boat that needs that most strength isn't in the hull, but around the cockpit buildup. The transition ot the reces and deck. Building up that area with patches of tight weave 2 or 4 in 2 layers with a third layer around 11 nd 2 o clock layers of changing orientation gives the best strength. I think. I lay them up presoaked in X patterns. With a third layer I cross the X. I also am a fan of adding a fiberglass rib on the inside of any place I am likely to sit on the boat AKA just behind the cockpit. Usually they are just a layer or two of 4 with the long strands arching under the deck.

In my thinking the one exception to using tighter weave, is building skid plates and abrasion pads. For that the weave is not nearly as important as the depth of epoxy built up in the weave, just more to grind through. Typically, I will apply presoaked pads of #6 for abrasion pads.

Thanks for sharing the numbers Pete!

I guess they just look like they are made of glass.

!RUSS

: Given that we are limited by the width of our glass fabric and the length of
: the boat, and that most bending forces will be in the longitudinal
: direction, at first glance it would seem best to align the cloth with the
: long fibers parallel to the keel. But a twisting force, like hitting a
: rock on one side of the bow then would hit the glass at a weak point. So
: maybe the best solution is to use 2 layers of thinner cloth, laid up on
: opposite diagonals? Some strength would be sacrificed parallel to the
: keel, but gaining quite a lot in the off-center impact direction.

: An additional benefit to using thinner cloth is the ease of obtaining higher
: glass-to-epoxy ratios. Per unit of cross section, the glass is on the
: order of 10 times as strong as the epoxy. The resin does 2 jobs, sealing
: water out of the wood and transmitting forces to the glass. Beyond the
: minimum to accomplish these two goals, more epoxy does not make a
: significantly stronger composite.