I am new to the sailing community and at the end of last year I purchased a 24' sailboat that I was told has a "swinging keel." The boat was dry docked and I recently went to check on it before it gets put back in the water. My first impression was that it was a fixed keel. However, I noticed that the bottem of the keel has a slit where it appears another keel would drop down. What kind of keel is this? Also, it appears that this piece is missing. Is this dangerous to sail? Do I need to replace this? Can I easily find a piece that would work? If it doesnt need to be replaced should I seal it up? I apologize for what are probably obvious questions, but like I said- I am new to sailing and trying to learn. Any help would be appreciated.