leak from skeg

I have a 1980 Swan 57 ketch.  We are experiencinga salt water leak of about 2 gallons per day.  The water is coming from aft, 12 inches forward of the rudder post.  At that location there is a structural fiberglass box beam with limber holes fore and aft.  The water is exiting the forward limber hole.  The aft limber hole is dry as is the hull back to the rudder post.

I am wondering if anyone has had a similar problem and what the resolution might be be.

Thanks

Joe Fantasia