Zinc Anodes

[johnseattle]

I have just seen an online ad for a Universal Zinc Anode, one that's on a wire that you hang over the side while moored. Presumably you connect the wire to your propshaft, I'm not sure.

On this site I have read Don Casey's words "There is an unfortunate misconception that a sacrificial anode can be mounted anywhere, even hung over the side on a string, and it will still perform its appointed duty. That is dead wrong! For an anode to provide any protection, it must be in electrical contact with the metal being protected."

My question, if anyone can please help, is this: will a free hanging anode work in this way if it is connected by an electrical wire instead of a string? Is anyone using one? (I've tried attaching a photo but keeping getting "invalid file name")

[nickmerc]

John,

I have one of the "fish on a wire" type anodes in addition to the prop shaft zincs. It has a copper clip on the other end which allows me to connect it to my back stay. My back stay is bonded to my engine, all other stays, and all thru hulls. I also have a galvanic isloator installed for when I am on shore power. For two years I have hung the fish over the side when at dock. The first year I did not have the galvanic isolator and all I noticed is some white scale forming on it. This past year it actually had growth on it. I do not think that it really did anything since the currents had to travel through stainless rigging and down a suspect wire. I think that these "fish" anodes are not very effective, but they do offer peace of mind.

[johnseattle]

Is it possible to avoid the need for anodes by simply disconnecting shorepower and batteries while at the dock? Or is the mere presence of dissimilar metals in water enough to case a problem? Thanks, all advice greatly appreciated.

[Fstbttms]

Originally Posted by johnseattle

Is it possible to avoid the need for anodes by simply disconnecting shorepower and batteries while at the dock? Or is the mere presence of dissimilar metals in water enough to case a problem? Thanks, all advice greatly appreciated.

While most corrosion issues are due to electrical issues aboard the boat in question; your neighbor's boat can have problems that affect you whether or not you are plugged into shorepower. And disconnecting your battery means no bilge pump, thereby risking the entire boat. And yes, galvanic corrosion is always an issue. So the short answer is, "No, unless you have no underwater metal parts, you cannot avoid the need for anodes."

Zincs are relatively cheap insurance. Why would you even consider trying to forgo that small expense?