That section of the hull is a recessed area where a cast bronze keel hanger mounts into the hull.I'm finding it difficult to get perspective on what I'm seeing. Is this where the cast iron meets the fiberglass?
The hangers bolt into metal "weldments" which are encapsulated into the fibreglass hull on either side of the keel trunk.
C22 New design versions have much easier access to this from inside the hull, due to a removable wood panel already being in the hull liner.
Reference:
FYI: When searching for this drawing, I found a website where someone fixed and rebuilt a C22 keel. It has a great photo of the keel hangers and weldments at the bottom of this page :
https://capnrehab.wordpress.com/category/catalina-22/page/2/