Thick is not necessarily strong and vice versa.
You are using 1700 which has no mat so it wont be as thick and you are using epoxy (I have been very happy w Raka) which is the right answer for biaxial without mat. I used alternating layers of 1708-1808-1708-1808-1708-1808 on the inside of my 1.5" thick Coosa core and it was almost too thick and caused fit problems. Plus it was heavier than I needed and expensive. I wish I had used glass without mat (1700 or 1800) as it would have been lighter, cheaper (much less resin), thinner and almost as strong (mat is not strong but it provides a good adhesion layer and separates the biax layers; kinda like core).
You should do a small test layup - maybe a foot or two square on something like cheap 1/4-3/8" plywood if you want to understand how strong the glass is. Rotate alternating 1700 layers by 45 degrees for a more uniform directional strength. Jump up and down on it and watch the plywood separate if/when you finally get it close to failure - that's one reason you are using Coosa. 6 layers of 1700 is ~0.180(vac layup) - ~0.20(hand layup) and scary strong. A 1.5" core separating the inner and outer layers is like an I beam with strength in all directions.
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