Join Date: Feb 2006
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A good solution
Many years ago we had a terrible time keeping bottom paint on our lead keel. We bought the boat used and the patchy texture of the keel paint was a racing no-no. I ground the paint away and went to bright lead before painting. The paint sloughed off in patches. I did this for two years and one day an old gent on the boatyard crew walked over and asked me what I was doing (actually he added some adjectives).
His response saved me a lot of work and money from then on. The gist of what he said is when you brighten the lead, you improve the chances for electrolysis between the lead alloy and the metals in the paint which leads to flaking and peeling.
My keel lead was alloyed with tin and antimony. The bottom paint had copper and tin.
He had three recommendations:
First let the keel oxidize to flat dark grey before painting. The lead oxide coating prevents the electrolysis. Second, use a paint without tin. Third if I was in a hurry use epoxy tar on the lead.
Since I had brightened the lead and I was in a hurry (it was mid season) I used the epoxy tar. In the remaining 15 years I never had to give the keel extra attention again.