This will give you an idea of how a cast lead keel with embedded "J" bolts is repaired;
• The damaged bolts are identified when the keel arrives.
• The bolts are removed through one side of the keel. This is done with a great deal of skill with a torch taking
the upper surface of the lead away.
• The old bolt is used as a pattern for the production of the new bolt. Most keel bolts are J hooked or bent in
• Once the old bolt is removed there is a “saddle” of lead remaining, creating the position for the new bolt to
• The new bolt is fabricated from new matching material.
• The new bolt can even be welded back into the bolt cage right in the keel.
• The new bolt is fused into place. Lead is melted back on top of the new bolt, fusing the original lead and
the new lead, making the repair as strong as the original keel.
• The entire surface of the keel is faired, both sides.
• The root cord is cleaned.
• The remaining original keel bolts are cleaned and readied for installation on the boat.
Disclaimer: No affiliation with MarsKeel etc...