I'm going to hazard a guess that it's leaking around your pivot bolt-and you may have to drop the keel to repair adequately. Remove enough trim in the area to find out exactly where it's coming from. If you, or previous owner, locked the keel in position then grounding could certainly have caused keel trunk damage. If the keel is free to swing because you don't lock it, didn't know it could lock, and has never been locked, you're probably looking at the pivot bolt as the source. You may be able to do a decent diagnosis on the trailer to determine whether the keel must be lowered out or not.
“Scientists are people who build the Brooklyn Bridge and then buy it.”
Wm. F. Buckley, Jr.