Join Date: Apr 2006
Thanked 189 Times in 185 Posts
Rep Power: 13
"The broker said that water from the bilge can seep down from the keel bolts and if it freezes in there, it can cause a bulge."
If there was sufficient water in the keel bolts to blow out the keel, the keel bolts need to be replaced.
Lead isn't a problem if you work with a fresh surface and roughen it up so whatever you are putting on it can get a grip. If you want to fo the repair the traditional way...you build a clay dam around the void, fill it with molten lead after preheating it, and it will bond in just fine. Basically you are soldering, that's all. (That's how dents in cars were fixed before fiberglass come out.)
After it cools, you file it down and finish overcoating it with epoxy, bottom paint, whatever suits you and matches the rest.
Lead is easy to obtain, you can get used tire weights often free from a local tire store, melt 'em down in a tin can over a propane torch, scoop off the dross (iron FLOATS on molten lead) and then just add some plumber's soldering flux and pour it into the void. (If you do this, do it outdoors and stay upwind of the solder, lead isn't healthy for you.)
Molten lead is fascinating, it looks very much like icy cool water, which of course is exactly what it isn't.