Crack at joint?
If it is the crack that develops between the f/g keel stub and an external keel, what worked for me was:
1. Clean up any loose material and let it dry comletely.
2. Fill gap with 5200 and let dry
3. Put a 3" piece of f/g tape over the the gap with epoxy resin (I used West epoxy and tape)
4. Fair and paint.
Heading back to Lake Ontario for this summer. Relatively few stops along the way from Grenada. Martinique, Guadeloupe, St. Martin (must have something to do with the French food), then Bermuda, New England and up the Hudson/Erie Canal. We were going to go via Newfoundland and Labrador but June remembered that one of the kids is getting married this summer - details, details!