Wednesday, November 2, 2011
Galvanic Corrosion 101
You may wonder why I'm holding a fish made out of zinc with such a dorky expression on my face. Well, the dorkiness is pretty typical, but the zinc fish is to combat galvanic corrosion - yet another new boating issue that I'm fascinated with because it involves metal literally dissolving on the atomic level. So cool, right? Unless it's happening to your boat, that is.
Ok, here comes a science lesson. When placed in an electrolyte solution like, ahem, salt water, a metal's electrons or ions can leave their original metal to hang out with a different, more attractive substance. If enough of the particles leave, you no longer have a working propeller or keel or other very important, very expensive boat part that you have to have to get to Tahiti.
Enter the zinc fish. If you're like I am, this little situation of all the metal on your boat deciding it would rather reside elsewhere is somewhat vexing, especially because it can happen quickly in a marina. But zinc, with its incredibly disloyal atoms, can save the day. When attached to another metal either directly or through a copper wire, zinc particles sacrifice themselves, leaving the particles in other nobler metals such as steel or bronze in place. In other words, the zinc will corrode instead of your bronze propeller. Here's a Seaworthy Magazine article that goes a bit deeper into the topic.