CPES
From what I have read, the CPES is thin enough to saturate and encapsulate the rotted core fibers. I've done some deck repairs by removing the top skin, replacing the rotted core with epoxy-saturated 1/4" marine ply, then returning the upper skin with more wet epoxy to bond the upper and lower skins. It was a messy, fussy job. I have another small soft spot on deck, and have been considering trying CPES (West Marine also carries a similar product, but they didn't know they carried a product like this until, after asking about it and being told that they did not, then I found it on their shelves). The idea is that the epoxy would harden and be strong but with voids in it similar to lava. Friends have drilled holes through the top skin, much as described above, then chasing the water by squirting acetone in through the holes until it showed up at the outer holes, then letting it sit for maybe a week, which allowed the acetone to evaporate. MAS Epoxies makes a less toxic acetone that I'm sure is compatible with at least their epoxy, if not the others. They don't make a REALLY thin resin like CPES, but their thin epoxy used for wetout of glass cloth and chopped fiber might work.
From what I have read, the CPES is thin enough to saturate and encapsulate the rotted core fibers. I've done some deck repairs by removing the top skin, replacing the rotted core with epoxy-saturated 1/4" marine ply, then returning the upper skin with more wet epoxy to bond the upper and lower skins. It was a messy, fussy job. I have another small soft spot on deck, and have been considering trying CPES (West Marine also carries a similar product, but they didn't know they carried a product like this until, after asking about it and being told that they did not, then I found it on their shelves). The idea is that the epoxy would harden and be strong but with voids in it similar to lava. Friends have drilled holes through the top skin, much as described above, then chasing the water by squirting acetone in through the holes until it showed up at the outer holes, then letting it sit for maybe a week, which allowed the acetone to evaporate. MAS Epoxies makes a less toxic acetone that I'm sure is compatible with at least their epoxy, if not the others. They don't make a REALLY thin resin like CPES, but their thin epoxy used for wetout of glass cloth and chopped fiber might work.