This refers to a problem exhibited by all the Catalinas built prior to mid-1988. With time a separation occurs between the keel and the keel stub, usually at the leading edge of the joint. The defect was attributed to the use of a wooden insert in the bilge between the top layer of fiberglass and the keel stub proper. The keel bolts pass through this insert, and it's thought that compression of the insert allows the keel to pull away from the stub, leading the to separation.
The problem first showed up on Wahoo about a year ago. Usually it's addressed by cleaning out the gap and caulking it, but you get to do that every time the boat is hauled. I didn't want to have to hassle with that and so went the route recommended by Catalina. The top layer of fibreglass was removed from the bilge and as much of the wood insert as possible was removed. The bilge was built back up using West System epoxy fibreglass. The keel bolts were cleaned, recaulked, and retorqued with new washers and nuts. The forward bolt failed when torqued, likely due to crevice corrosion from water getting around the nut, and was sistered with a 10 inch long, 1/2 inch diameter stainless steel lag bolt. The keel joint itself was ground out, covered with West System epoxy and fiberglass cloth, and refaired. I did most of this work myself, but got professional help on the fiberglass.
All the work was done according to the factory recommendations. A good summary of these is found here.