: Good stuff Sam! And for me at least, your data has an interesting surprise.
: If I have interpreted figure 6 correctly, lay-ups with more of the total
: glass placed on the impact side were stronger. The notion that, since
: glass is stronger in tension, the heavier part of the lay-up should be on
: the inside is not supported by your tests. This could mean we get to have
: our cake and eat it too. By that I mean we can put more glass on the
: outside to increase strength while at the same time benefitting from extra
: abrasion resistance.

: Since my current project is only glassed on the outside, I will be thinking
: about alternatives to my plan of continuing with 6 oz satin s-glass for
: the inside.

: Ted

Ted,

Things get pretty complicated as soon as failure initiates, but up to that point the impact side is mostly in compression. Since glass is stronger in tension than compression, that means failure should tend to happen first on the impact side. So having more glass on the outside should delay the onset of failure.

I do have some results (to post sometime soon) that show what happens with enough impact energy to cause damage, but not perforate the sample. In that case there is damage on the impact side, but slightly more damage on the inside! So, thicker outside appears to delay the onset of damage (more energy to peak load) and give us a surface that is harder to ding and scratch. An interesting question is, what if we put all the glass on the inside? I suspect that a boat made this way would be very resistant to puncture, but would sustain all sorts of other damage.

Sam