Welcome to the "Learning Curve"

[Lou.Catozzi]

I recommend that you skin the outside surface of your foam before applying the epoxy/FG.

I glassed directly over a combination of foam, light weight spackle filler and guide coat primer, and had (am still having) troubles... small areas of lack of adhesion and some hand sized blistering (puffed out areas as if something was still out gassing... which I will need to drill and see if I can get to lay back down and adhere using the syringe method.

KC,

Thanks for stopping by and offering advice. If $50 worth of 1/8" ply is the answer to all the problems you have been having I am all for it - hang the weight. I am curious, though, if you know which bond layer(s) failed for you. Foam to spackle, spackle to primer, or primer to epoxy. What brands were you using? I am using Dow Blue Styrofoam and Raka Inc non-blushing epoxy resin and hardener.

Lou

[KCStudly]

I used the blue foam, West System, forget which spackle at the moment ("light weight" vynil... may have been DAP) and Rustolem rattle can. Not sure if the problem is related to sub surface GS or GG. I used GG for letting in all of my blocking and I used GS in a couple places for gouge filler. Unfortunately, as far as I can tell, neither of those directly correlate to the puffy areas. The strange thing is the puffy areas didn't show up until literally year(s) after I stopped working on it in earnest.

[Lou.Catozzi]

I used the blue foam, West System, forget which spackle at the moment ("light weight" vynil... may have been DAP) and Rustolem rattle can. Not sure if the problem is related to sub surface GS or GG. I used GG for letting in all of my blocking and I used GS in a couple places for gouge filler. Unfortunately, as far as I can tell, neither of those directly correlate to the puffy areas. The strange thing is the puffy areas didn't show up until literally year(s) after I stopped working on it in earnest.

I talked about your concerns with a friend of mine who restores small aircraft and has done quite a bit of fiberglass work. He does not use Dow Styrofoam but rather an open-cell foam. He agreed with you that another layer of 1/8" ply over the blue foam would be a good idea so that is the current plan. I've just got to seal it all very well since the 1/8" birch ply I have available to me does not have a waterproof binder.

[capnTelescope]

Howdy, crosstown neighbor. Congratulations on your retirement. Now that your time is your own, you'll have this project done in a teardrop-time jiffy.

Thanks for the major update. Looking good! You do nice work. I especially like the A/C ductwork. It follows the same approach I used, only done better.

[Lou.Catozzi]

I especially like the A/C ductwork. It follows the same approach I used, only done better.

It's always easier (and certainly quicker for me) to see what someone else has done and tweek it than it is for me to come up with a particular design feature on my own.

“Imitation is the sincerest form of flattery that mediocrity can pay to greatness.”

― Oscar Wilde