We learned the value of moisture meters (or lack thereof) and destructive testing the hard way, when we were told that we not only had significant moisture issues with the hull (likely water in the core) but also in the knees (that connect the chain plates with hull and deck). Luckily enough, our core samples of the hull proved that the core was in good shape and actually dry.
With the knees, we went through significantly more panic. We were essentially ready to take the mast down, transport the boat to Haverhill, remove most of the main cabin’s woodwork to have professionals replace the knees. This was on the advise of numerous experts. Inconclusive moisture readings and the strong suspicion of crevice corrosion were the reasons.
Luckily enough, Sean convinced us to not panic and to expose the chainplates to see what we were really dealing with.
Long story short, we removed the bolts on starboard and they were in good shape. We carefully cut the skin away from the aft knee holding the lower shroud’s chain plate. It also looked good. To be safe we pulled the plate out and it indeed did not have crevice corrosion issues. A metallurgist friend of Josh even looked at the plate with a 40x microscope and could not find any problems.
We therefore decided to put the plate back in and for safety sake replace the bolts with new ones. After looking into grade 8 bolts (which are harder but not stainless steel) we went with 316 stainless steel.
We sealed all the cracks around the plates and replaced the caulking and are good to go again. Good to know that the chainplates are in good shape before leaving for a transatlantic crossing.