Prior to 87 or 88, Catalina used wood in the keel stub. It was encapsulated with epoxy but a common practice in bilges is to mount bilge pumps, pump switches and hoses to the bottom of the bilge with screws. If the screw penetrates into the wood, water can seep in and rot the wood.
Correction - CTY used no epoxy in the keel buss or on the compression post support. If it had encapsulated the mast support it wouldn’t rot (water attacks it from the outside.)
The rotting of the keel buss wood plank and the smile aren’t exactly as described. Been there, removed/rebed my keel in 5200 and got the tee shirt.
Unlike the mast support, encapsulating the keel wood (reportedly both planks and plywood had been used) in anything would not have much effect because of the way it is attacked. Bilge water travels down the keel bolts threads, not a tiny, tight threaded hole from a pump mount. The margin between the thread crest and valley, creates eight long continuous “open tunnels” for water to get to the keel buss and joint bedding.
My plank was not bad, damp but not rotted, but my keel joint was nearly half gone. Meaning punky and like wet chalk when the fairing was ground off and I got into the joint bedding. It’s just a polyester chopped mix bedding which is the cause. Polyester resin is hydophyllic (attracts) and degrades when remaining soaked (same reason hull blisters occur.). Epoxy resin is not.
Interestingly the worst point was the aft 1/2 of the joint, not the typical smile area (my aft keel bolt nut was finger tight, which undoubtedly contributed to the joint attack.) The forward 1/2 of the joint (smile area) was competent.
The joint and any crack/drips that manifest themselves when on the hard (water leaked down from a 1’ portside crack in the fairing) are from the inside out, not from water getting in from below. In my case (former northern boat) the joint deterioration was no doubt accelerated due to freeze/expansion/thaw over 10 years while she was pre loved.
Anyone interested in more info/fixed on the keel buss or compression post support issues, there’s hours of discussion on the IC30A forum there for a search. Also on the C34.org forum and techwiki site.