Denise,
This is correct, the Keel is encapsulated, I had an O'day 28' and 30'. I struck a obstruction last year with the 30. Took a monster chunk off thr bottom, and partied all the faring and gelcoat around the trunk of the keel. The boat started taking on watr through the base of the keel and filling up the bildge every 20 minutes. The
pumps were able to keep up and she was hauled that night at the shipyard.
After the surveryor was finished looking at her they replaced the missing lead, at the base of the keel, and glased everything, next the work began at the trunk. They ground everything out where the crack was and refilled and applied some gelcoat, sanded, painted and bac in the water she went.
So to answer your question, JUST A LITTLE FILLER.
She was a great sailing boat won alot of races with her, I sold her last season and bought a C36
Good Luck