Well I liked to tell you it's just simply tightening the keel bolts. But I would be worried of additional issues like corrosion of the bolts causing leakage and/or possible failure of the bolts. Seepage of salt water by the keel bolts means the seal between the hull and the keel has been compromised, failed, or the bolts have loosened or are separating from the keel. All potentially very serious stuff. I would recommend doing some serious investigating with a good qualified professional which will not be inexpensive. Find a good boat yard you trust and good luck. Bad things happen when a sailboat loses a keel.
Curtis Johnson
S/V Aurora
2002 Hylas 46 #41