Though Id post up this repair as it might help folks with weight gain… 
Someone dropped of a Rawson fish with a busted FCS plug. The guy just asked to get the plug replaced.
The board was badly neglected, seemed like 10 years worth of seaweed imbeded into wax. The board felt “greasy”. I dislike working on “dirty” boards, so I cleaned it up, removed the old wax from the deck and some from the bottom.
While I was removing the wax I felt one area on the deck was kinda squishy. No visual defects, but definetly the glass was not attached to the blank. Way to big to leave as is. Said it to the guy, he said to go ahead and repair it.
So I went ahead and as carefully as I could cut out the defect area:
The cut section still had about 1/8-1/4" layer of foam attached to it. So that made the equivalently deep hole in the deck.
There was no way I was filling that with resin and filler. Thats just waistfull and adds weight.
So instead I hotwires a few EPS panels (1/4 thick). Because the panels were shorter than the hole, I hat to use a few of them to span the lenghts.
Using the cut out section of old glass I marked out the shape of the hole as accurately as possible:
Then a bit of sanding and test fit (note I also sanded the floor of the hole flat):
I then used woodglue to attach the EPS foam to PU blank section by section. Spread it out evenly over both surfaces:
Waited a day for it to dry and then sanded the whole thing with P100. The gap between the foam and deck was later filled with resin filler mix. (RR epoxy obviouly)
I kept the old cut out section of glass and just glued it back over the repair with epoxy. To stop the epoxy from draining into EPS I loaded it up with q cell filler:
Then glass over with 4 oz:
Hotcoated after that (no pic sorry) and voila.
Thanks for tuning in!