Starting thread on anodes to spread good information

Hi Guys,

Here is some basic advise on what anodes to be used where:

About sacrificial anodes


Magnesium has the most negative electro potential of the three and is suitable for zones where the resistivity of the electrolyte (soil or water) is higher. These are usually onshore pipelines and other covered structures, although they are also used on freshwater vessels and in water heaters. Sometimes magnesium’s negative ability can be a weakness: if the potential of the metal turns out to be excessively negative, hydrogen particles can develop on the cathode surface, causing hydrogen embrittlement or peeling of the coating.


Zinc generally has a low drive voltage, which means that it most likely cannot provide adequate protection in soils/waters with higher resistivity e.g. in freshwater. Zinc works perfectly fine in Saltwater or slightly brackish.


Aluminum anodes have advantages, for example, they are lighter and have a much higher capacity than zinc. In any case, their electrochemical properties are not considered to be as stable as zinc, and more consideration needs to be given to how they are used. Aluminum anodes are passivated when the chloride fixation is below 1,446 ppm.

[View Aluminium anodes]

I’ve found that anodes last a lot longer if you apply 5 coats of epoxy primer.


If you have some boats directly grounded to shore power around you, just leave off the anodes and do the same, you can use theirs :rofl:


Protip: For added protection, connect the shore side of the earth isolation transformer to battery positive.

Not mentioned are the impressed current systems such as CAPAC (Cathodic Protection Automatically Controlled) that provide automatic protection against galvanic corrosion from attacking submerged surfaces across a broad range of sea-going vessels and fixed floating structures.

I hope you are not being serious…

No, but you just passed the Turing test. Congrats.

Awesome. For your information, the anode won’t work if you paint it over? Hence, why I hoped you were joking around.

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My favorite is to connect one phase of the generator to the port drive shaft and one to the starboard. If you do that you won’t need to bother painting the anodes :wink:

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If the anodes aren’t covered prior to hull painting they will get coated with whatever paint is being applied. The painters do not care and will not stop for such minor details.

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Sorta brings to mind videos I’ve seen of that river in Ohio (?) with all the fish leaping into the air around the boat… You could include SCUBA divers in that, too…

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Anode dude is just trying to drive traffic to his site, but being serious for sec divers can die that way and swimmers too. I have a diver working right now actually and I have everything off.

How about if you use water based paint? :thinking: :laughing:

You need this kind of fish in those waters:


Yep - I know you were just having fun :slight_smile: Anode dude needs to realize this isn’t the place for “Boating 101” topics unless you want a lot of harassment :grinning_face_with_smiling_eyes: