Join Date: Apr 2006
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"Marine bronze is a bronze. I don't think it's a stainless steel."
My point exactly. (I have a good poker face online, don't I?)
Bear in mind that the lead used in "lead" keels is not 100% pure lead, it has substantial amounts of other materials, some by intent, some by accident. As I understand it, keels aren't considered a critical alloy and that means recycled lead, tire weights with antimony and other content, etc., may all be in there. I'd want to look into exactly what alloy was being tested/used before taking any test as "substantially" correct. (Perhaps you'd know?)
I know lead isn't totally inert, but who runs around with a bare lead keel anyhow? There's usually a heavy layer of old paint and more copper-bearing bottom paint over the lead, which essentially jackets it in sacrificial copper versus any stray current to other parts of the boat. And only a fool (or a prop saft salesman?) would be running a metal shaft and dissimilar metal prop without some zincs up there...wouldn't that make the lead keel a "distant" issue? Literally?
Keelbolts are theoretically embedded dry, solid, "bonded" by the lead cooling around them as they are cast in place. Galvanic corrosion in there shouldn't be a problem unless you like to keep a wet bilge. Heck, the classic way to build wrought iron fences was to pour molten lead into the ground (or masonry) and then stand the wrought iron in the lead, cast in place. When fencework is done that way it lasts hundreds of years, versus rusting out in a decade when the same ironwork is simply embedded in concrete or cement (the modern way). Lead and iron manage to live together very nicely.