Each year when I haul out, my lead keel has patches of creamy coloured calcium carbonate adhering to it. They look rather like patches of bubbles clustered together, but they are solid and can be removed bit by bit using one's fingers. their underside is flat where they adhere. Various members of a chemistry faculty have looked at the problem but cannot solve it. I have had the material identified under an electron microprobe, so there is no doubt about what it is. A good clean and a coating of epoxy makes no difference. I don't see this phenomenon on other boats so what is happening. Nobody believes it is electrolysis, but I wonder -- lead is sometimes hardened with calcium carbonate, and perhaps one part of the keel becomes anodic to another part...but IS THIS POSSIBLE....HAS ANY OWNER HAD THIS SAME EXPERIENCE?
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Not very good in chemistery but
Not very good in chemistery but can antimony be confused with calcium carbonate? The reason I ask is as far as I know when you cast a keel the preferred additive is antimony. Of course a lot of small shops use scrap lead so you don’t know what you are getting but still I haven’t heard of using calcium carbonate in a keel casting. Is this used if the lead is being cast for other purposes? But to answer your question, no I haven’t seen this before and I have looked at a lot of cast keels. Maybe you should talk to Mars Metals. They specialize in casting keels and might have some ideas. All the best, Robert Gainer
Not very good in chemistery but can antimony be confused with calcium carbonate? The reason I ask is as far as I know when you cast a keel the preferred additive is antimony. Of course a lot of small shops use scrap lead so you don’t know what you are getting but still I haven’t heard of using calcium carbonate in a keel casting. Is this used if the lead is being cast for other purposes? But to answer your question, no I haven’t seen this before and I have looked at a lot of cast keels. Maybe you should talk to Mars Metals. They specialize in casting keels and might have some ideas. All the best, Robert Gainer
Calcium carbonate? isn't that Alka Seltzer?
Maybe your boat gets seasick, and drops a few tablets?
Maybe your boat gets seasick, and drops a few tablets?
I'll take a stab at this
Do you moor or keep your boat in a slip? In a slip someone elses electrical faults can induce stress on your hull through the water. Maybe a nearby neighbor has an electrical leak into the water. How often do you have to replace your zincs? Is the lead keel grounded along with the engine to the zinc? I assume you winter your boat on the hard but if you over winter in the water at a slip you could really be getting someones electricity leak attacking your lead keel. If you keep your boat on a mooring then could there be some electrical leak from your boat that is getting to the keel to induce the precipatate forming by one part becoming anodic with the other? Otherwise go with Robert Gainer's advice. He's been across the pond a few times.
Do you moor or keep your boat in a slip? In a slip someone elses electrical faults can induce stress on your hull through the water. Maybe a nearby neighbor has an electrical leak into the water. How often do you have to replace your zincs? Is the lead keel grounded along with the engine to the zinc? I assume you winter your boat on the hard but if you over winter in the water at a slip you could really be getting someones electricity leak attacking your lead keel. If you keep your boat on a mooring then could there be some electrical leak from your boat that is getting to the keel to induce the precipatate forming by one part becoming anodic with the other? Otherwise go with Robert Gainer's advice. He's been across the pond a few times.
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