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matt_colie

wrote:
I am to the stage of casting the keel for my project. Please comment
on my proposed method of making the mold:

--make a male plug out of styrofoam with a thin coat of bondo for
fairing and smoothing.

--coat the plug with half a dozen thin coats of no texture drywall
mud.

--suspend the coated plug in the mold box and surround with cement.

--burn out the styrofoam and bondo, leaving a smooth female mold for
pouring the lead into.

note: I have never cast with sand and have no desire to learn
another new skill.

TIA mm
You are setting yourself up for a disaster that includes violent steam
explosions and running streams of molten lead.

Sand and molasses because it could be baked dry.
For a keel mold, the mold box work has to be extremely strong as the
molten lead (~600*F) will exert approximately 11 times the hydraulic
pressure of water.

Look up a magazine article that was about a decade ago in either Wooden
Boat or Good Old Boat about the well meaning guy that tried to recast
his keel.

Good Luck Guy

Matt Colie
Third Generation Boat Builder, Lifelong Waterman, Licensed Mariner