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Case Study: MarsKeel Yacht Bolt Replacement Project For Lead Keels

Bolts are used to secure a keel to the base of a boat. If the bolts are damaged, the safety of the vessel can be compromised. MarsKeel, a North American leader in keel technology, recently worked on a keel repair project for a Virginia-based client who owned a Hunter yacht.

The Challenge

Cobbs Marina contacted MarsKeel to replace the bolts for a Hunter Yachts 42 wing keel. MarsKeel then arranged to have the keel picked up at the yard and brought to their facility for repair. The main reason that a bolt needs to be replaced is corrosion.

Since it was difficult to ascertain the extent of damage to the bolts with the keel attached to the boat, engineers separated and lowered the keel a few inches from the fiberglass hull for a closer inspection.  As is generally the case, the bolts were corroded. The corrosion was located in areas where the bolts passed through the fiberglass sump or hull bottom. The presence of water and lack of oxygen leads to corrosion. Even 316 Stainless Steel will still corrode in these conditions.

Our Solution

MarsKeel Technology has developed a proven and cost-effective methodology to replace bolts. The general process for keel bolt replacement is as follows:

  • Melting away a portion of the casting to release the bolt
  • Defining the bolt material and manufacturing the new bolt as per the original material used
  • Positioning new bolts into the recess left by the original bolt and re-fusing the lead over it
  • Painting the re-fused keel with an Interprotect 2000E barrier coat
  • Reinstalling the keel to the vessel at the yard

So, whether you’re repairing your old keel or looking for the best keel technology to power your next voyage, MarsKeel Technology is here to help. For information about the maintenance and repair of keels, read our blog.


MarsKeel is North America’s largest keel manufacturer, supplying keels to the top production yacht builders and offering repair and modification services for over 40 years. Contact us today for your keel production, repair, and modification needs.