Two Layers of 3/4 CSM versus One Layer of 1.5 CSM

[froggy1150]

Csm is like a "primer". Its hair like random structure is good for filling voids. The "hair ends" stick into all the valleys and crevasses. Then the woven goes on top for the real strength. Granted any glass will add some support but biaxis is stronger. That's what 1708 is..... a 2 in 1 hybrid. When I did mine I did csm then 1708 with the csm side up for sanding. If you sand into biaxial cloth it's not happy and gets weak.

 

[mickyryan]

CSM is strong in all directions. Not as strong as the equivalent weight of cloth, provided it's fibers are laid at a bias.

Clearly 5/8 plywood with CSM is stronger than 1/2 plywood with the same CSM layer.

The problem relating to str from csm is that theyvare short strand and dont transfer the energy along a long strand like woven or fabric , this is how it was explained to me as i always felt same way you do about csm but there was a guy on the forums for awhile that worked with glass all his life and he schooled me on it i have no proof either way just parroting what i was told also layers of glass fabric is where strength is built not just 1 pass but i reckon 1 pass is better then nothing

 

[76SeaRay]

I have started laying covering on the deck. I am working from the bow to the stern. The pics below are my V Berth. I laid one layer of 1708 and then one layer of the 0.5 CSM on the deck. I used only one layer of 0.5 CSM since once I put the "under cushion storage boxes" I will be adding 1708 tabbing and more CSM. I also plan to paint or gelcoat these. I am adding small peanut butter fillets in the "storage boxes" right now, then will finish these out before putting the cabin bulkheads in attached to the aft end of the boxes and the fiberglass dash above.