Originally Posted by EXCS_CT
OK. I guess rational reasoning and practical thought (yours) have overridden gut level emotional reaction. I will be patching the hole and soft spots and not trying to replace the entire floor. The attached photo shows the first replacement in place. It will get another coat and the underside will also get fibergalssed. The soft section in the rear will get a similar treatment. I am thinking I will then put down a layer of underlayment to level out the floor prior to laying down a new vinyl floor.
Nice work and QUICK!. At the risk of pointing out the obvious, all that protects the plywood from rot is the fiberglass coating. When ever I put a hole in my floor, I drill the hole oversize, tape the bottom, fill with resin, let it cure, then drill the hole size I need in the resin. The result is a sealed floor. The vents I used were about 3/4" in diameter.
Here is what I used for a drain in my floor.