Cleaning up anodes

[tinkiewinkie]

Apologies for the fact that my very first post on this forum is looking for help rather than giving it but I need advice about the anodes on the mobo I have recently purchased. Probably magnesium as its been used in fresh, brackish water, no significant erosion but they are covered in a hard rough coating. Possibly calcium or other mineral salt???

Anyway, can I just clean them up ie back to bare metal? Will they then be serviceable? Opinions among my boating cronies varies significantly.

Thanks for looking.

 

[RichardS]

Apologies for the fact that my very first post on this forum is looking for help rather than giving it but I need advice about the anodes on the mobo I have recently purchased. Probably magnesium as its been used in fresh, brackish water, no significant erosion but they are covered in a hard rough coating. Possibly calcium or other mineral salt???

Anyway, can I just clean them up ie back to bare metal? Will they then be serviceable? Opinions among my boating cronies varies significantly.

Thanks for looking.

Welcome to the forum.

No problem with cleaning them up to "revive" them but do not use a wire brush. I just scrape the white deposit off with an old screwdriver. You don't need to be too precise about this - just remove the large / deep lumps and a quick scrape of the rest.

Richard

 

[gordmac]

I would think cleaning them would be fine, you maybe need to watch you don't get bits of steel in them though from say a wire brush though.

 

[dombuckley]

If she's been in fresh water, and there's calcification on the anodes, it's far more likely that they are zinc. Magnesium is much more active and usually stays clean in FW.

If you are keeping her in fresh water, I would change them for magnesium equivalents. If in seawater, scrape / chip them clean and continue to use.

 

[tinkiewinkie]

Many thanks. Is wire brushing a no-no just because of the possibility of leaving bits of steel embedded? Or is it the combustible nature of magnesium, if thats what they are, thats an issue? I had half-thought of gently taking an angle grinder to them. Is that a very silly idea?

 

[tinkiewinkie]

If she's been in fresh water, and there's calcification on the anodes, it's far more likely that they are zinc. Magnesium is much more active and usually stays clean in FW.

If you are keeping her in fresh water, I would change them for magnesium equivalents. If in seawater, scrape / chip them clean and continue to use.

Thank you. Is there some way of positively identifying which metal they are made of, like a marking on the anode itself? I havent been able to spot one but wonder if its hidden under the coating itself. The anodes are of the McDuff 78B variety. Advice regarding magnesium noted. Seems I might have to buy new anyway.

 

[KellysEye]

>If she's been in fresh water, and there's calcification on the anodes, it's far more likely that they are zinc.

If they are zinc you can get calcium of with Muriatic acid but don't get it on your skin.

 

[Avocet]

Ours is in fresh water at present and uses magnesium anodes. They corrode very quickly when working properly. I agree Dom and Kellys - those sound more like zinc (or maybe aluminium). Just scrape and replace.

 

[tico]

Zinc anodes are heavy
Magnesium ones are very light

 

[tinkiewinkie]

Zinc anodes are heavy
Magnesium ones are very light

Doh, why didn't I think of that. They are extremely heavy for their size, ideal weights for holding down the corners of tarpaulins.

Many thanks