I follow battleship New Jersey on YouTube. One of the recent topics is how the hull around the propellers can corrode more than other areas of the hull. Because of this, the navy installed sacrificial anodes.
Why would a large ship corrode around the propellers more. How to anodes prevent this?
In: Chemistry
Different metals protect each other from corrosion depending on where they fall on the [galvanic scale](https://en.m.wikipedia.org/wiki/File:Galvanic_series_noble_metals.jpg). Propellers are a copper alloy like bronze and the hull is steel. Steel protects bronze because it’s higher on the scale. Zinc protects steel because it’s higher again on the scale again. The zinc annode is sacrificial. It protects the other metals from corrosion by itself corroding. It is simply replaced periodically to maintain protection.
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