After retrieving both ends of the keel cable, we were able to look at them and try to determine what caused the cable to fail. Some ideas came from details when I ordered the new cable. After looking at the two pieces, I am fairly certain that I know what the issue was, and how to prevent this from happening again.
I purchased the entire keel system replacement kit from Catalina Direct two year ago when I was looking at repairing my first boat. That boat never made it in the water. When I purchased my current boat, Odin, the keel seemed serviceable for at least a season. We sailed for a season, but the next spring I decided to replace everything.
The kit from Catalina Direct comes with a new volcano tube, a new cable, and a new turning ball. The install was fairly easy, and I even replaced the winch at the same time. When I went to order the new cable though, I noticed a warning on the description that does not exist when I ordered the cable with the kit.
Whenever I am at dock, I have always lowered the keel, and have never bothered to take the slack out of the cable. It seems like in forums, this is the preferred way to sail, as it avoids the cable hum that happens on Catalina 22s. Right away I had a suspicion that this was what happened. But I would need to pull the boat to know for sure.
Now that we have pulled the boat and retrieved the attached piece from the keel, I am almost certain that this is the cause of failure. At the tip of the swag fitting was a shiny section. This area has clearly been warn down from where the cable was rubbing against it. The cable is a fairly flat cut, and the frayed cables were not there when the cable was first pulled up after breaking.
As far as preventing this from happening again, I will be following the suggestion on the Catalina Direct website, and removing slack after lowering the keel. Hopefully this will increase the longevity to have the cable last more than a season. Inspection of the entire lifting system is one of the most important that needs to happen on any swing keel.