Keel Bolt Replacement in Lead Cast Keels

Do I need to replace the keel bolts?
Why? This is why. Safety.

The entire reason that a bolt needs to be replaced is safety. A corroded bolt can impact the safety of the boat and those on board. MarsKeel Technology has developed a proven and cost-effective methodology to replace them.

The Keel Bolt Replacement Process

MarsKeel is a North American leader in keel bolt replacement for cast lead keels. Our General process is as follows:

  • Transporting the separated keel to our facility for repair
  • Melting away a portion of the casting to release the bolt
  • Defining the bolt material, if there is no information on file for that keel.
  • Create new bolts, that are to be installed in the keel.
  • Positioning the 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

For more information about our bolt replacement process, click here.

How to Prevent Keel Bolt Damage?

Bolt corrosion usually occurs when water is left standing in the bilge of the vessel or if the hull keel joints are compromised in any way. Most damage can’t be seen as it occurs in the area between the top of the keel and below the internal washer plates in the bilge. Follow these steps to avoid corrosion:

  • Maintain as dry a bilge as possible
  • Inspect and maintain the watertight hull keel joint regularly
  • Look for signs of rust which occurs if water is allowed to stand in the bilge or to pass through the weak hull keel seal. Typically, these are rust stains on the outside of the keel starting at the hull keel joint.

How Rust Damages Bolts?

Once the damage reaches a rust-stain stage, there is no option but to replace the bolt. Even stainless steel rusts under the right conditions. Unfortunately, the keel bolts that pass through the FRP sump bottom are susceptible to rust. Always remember:

  • Water present + no oxygen = rust
  • Rust = weakened bolts
  • Weakened bolts = unsafe conditions

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, click here.


MarsKeel is North America’s largest keel manufacturer, supplying keels to the top production yacht builders and offering repair and modification services for over 35 years. Contact us today for your keel production, repair, and modification needs.