After removing the chock we countersunk the screw holes to provide extra area for the sealant
Ocean sailing is incredibly hard on a boat. Every one of the hundreds of thousands of waves we’ve encountered causes a loading/unloading cycle on the rigging, the sails, and the hull. When the wind picks up, the forces just get higher – the force of the wind on the sails increases as the square of the wind speed, so going from a 10 knot breeze to 20 knot winds means that the forces have increased 4X.
Mike hard at work repairing the chock
What this means in practice is that all of the fittings and attachment points for gear on the boat gets a real workout. A perfect example is the chock for our midship cleat – we use this to run the afterguy for our whisker pole. The chock itself is a beefy chunk of stainless steel, and it’s attached to the boat by three 3/8″ stainless bolts.
Butyl sealant around the screws below the chock
The constant cycling loads broke down the sealant between one of these bolts and the hull, and we started to get a small trickle of salt water under the fitting. Our first attempt at fixing this was to remove the offending bolt and add more sealant from the top. This slowed the leak, but didn’t completely stop it. So, we had to completely remove the chock, create some new rebates to accept more sealant, and then reinstall it.
Reinstalling the chock
For the boat nerds out there, our sealant of choice for a job like this is butyl rubber. It sticks tenaciously to most dry surfaces, but it sticks to itself even better. So, it’s relatively easy to clean up after a job just by using a small ball of butyl to pull away any stray sealant. The main drawback of the stuff is that it doesn’t really have good adhesive properties – but it’s perfect in an application like this where bolts provide all of the clamping force.
Removing excess butyl after installation
