I don't discuss my member
Join Date: Feb 2003
Location: Under a boat, in a marina, in the San Francisco Bay
Thanked 34 Times in 33 Posts
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Of course it is possible to over-protect a boat with zinc. When creating a galvanic cell (such as when protecting an underwater metal part with an anode) the water around the part becomes alkaline. Many anti fouling paints are softened and blistered by alkali. Hydrogen bubbles may also form under the paint surface, causing it to lift off. The more anodes you use, the worse the effects. I have seen many, many examples of anti fouling paint being damaged like this.