[prairieschooner]

Thanks Tom, just trying to be helpful.
Todd, I haven't seen the rot in the bathroom floor so really don't know how bad it was. I do know that the plywood used in our tank bay appears to be a mahogany that hasn't fared well with water and turned black as described.

Some problems can be solved with a Penetrating Epoxy. I am not a big fan of using this in large areas where the wood obviously should be replaced but in some smaller areas that are hard to get to it does come in helpful. This is so effective that the US Coast Guard allows some repairs using a product like this.

Here is a link you might find helpful, look under wooden boat and then rot repair;
http://www.westsystem.com/ss/