You didn't happen to own a 26D did you? My 26D has about 2 bags of ready mix fiber glassed in the front of the water ballast! Who ever did it tried unsuccessfully to seal it in. So I figure there is about 75-80 lb given the density of concrete in water.
Some PO's are just plain crazy.
Pic is the patch I found in my V berth. It was leaking so I opened it up. Surprise! Concrete!
