It is the wood at the keel on which the compression post sits that I was thinking about above. If so, it is either rotted or it will rot; either way, whoever thought that putting wood, encapsulated or not, in this location, should have his sanity questioned and buy up all the C30s so constructed on his own nickle.
Funny, Hull #10 has no problems there.
Previous owner(s) had drilled holes in the deck that caused the deck to collapse under the mast, but the compression post and bilge block are still sound after 35 years.
There is no reason not to use wood here, or in deck cores or anywhere else. Dry wood does not rot. Most rot is owner inflicted.
Most surveyors will know what to look for. If the wood is punk, get a repair estimate and have the owner either repair it to pass survey or deduct the cost from the purchase price.
The boat is 20+ years old. You are going to want to pull the mast and do a good inspection of rigging and wiring anyway unless the owner has done so within the last 5 years and can provide the report. While the mast is out, fixing any problem with the bilge block is not a big deal. Many C30 owners have done it themselves.
Randy