Quote:
Originally Posted by Boonie23
My question is the previous owner used two sheets of 3/4” marine ply but did not glass inbetween the sheets. He used thickened polyester resin with cabosil. It seems very well bonded but I’ve been told usually there should be glass inbetween the sheets. Do we think it is good with just the thickened resin?
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Glass between the plywood sheets dose little to aid in strength and is not necessary at all. I sometimes use CSM mainly to hold extra resin as the wood will wick it up. Thicken epoxy will not absorb into the wood as well and I actually thin my resin instead of thicken it when bonding ply. But I use VE or poly not Epoxy between them. Thicken epoxy is fine and honestly the original way they boat was built the ply were just stapled together with no bonding resin. The transom strength is in the outer and inner layers of glass on either side of the core. The middle of the core dose little for strength and the outside layers build an "I" beam type structure. If you add glass in the middle it is really just a waist and adds unnecessary weight with little strength benefits. I use thinned resin between mine mainly just to make the wood soak up as much resin as possible to aid in water proofing the wood. I used to add several layers of glass in the middle many years ago but learned that it is better to keep it on the outer sides of the core. (some old wise men up here taught me better) You can rest at ease long as the outer core lay ups and tabbing have good thickness.