Freshening up anodes

galeus

galeus

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I was working on my boat in the boatyard yesterday and observed one of the mechanics working on the props of a motor cruiser with a angle grinder/wire brush.
I noted that he didn,t touch the anode on the hull which looked quite scaly (something I always have done- to get a fresh surface on it).
I asked him why he left it alone and he told me you should never work on them with anything metallic, not even a scraper, only sandpaper, something Volvo had taught him.
Is he right; it does not make any sense to me.
 
I have read this instruction before and, like you, I fail to understand the logic of it. I have seen it suggested that particles of the steel from a wire brush would become lodged in the zinc, but suppose they do? I cannot see any downside in that, they will soon go. I wire brush mine and file them when they become really pitted.
 
The attachment fittings are steel. So the presence of steel itself cannot be harmful.

Now zinc, although essential to life in a small quantity, is poisonous. I wonder if the instruction is garbled advice not to raise a cloud of zinc particles, and ingest them.
 
I have seen the same explanation as Vyv but unless you embed so many bristles from the wire brush in it that it resembles a hedgehog I cannot believe they will have any effect.
As he suggests the zinc around the odd one or two will some corrode away and they will fall out.
 
Other than making sure that I don't paint them I've never done anything with my anodes. I've not filed them, not sanded them and not wire brushed them. I've played the pressure washer on them at the end of the season but that's it. They've never built up much by way of a thick white coating but just slowly fade away and they are eventually replaced.

From the comments here, I'm beginning to think I should do more. Or am I just fortunate with my boat?
 
Rigger Mortice said:
Other than making sure that I don't paint them I've never done anything with my anodes. I've not filed them, not sanded them and not wire brushed them. I've played the pressure washer on them at the end of the season but that's it. They've never built up much by way of a thick white coating but just slowly fade away and they are eventually replaced.

From the comments here, I'm beginning to think I should do more. Or am I just fortunate with my boat?
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Don't think you need to do more. I don't touch my anodes either, just replace them when required.
 
I believe that exposure to fresh water is what causes a zinc anode to build up a white coating. As the water is not particularly saline either in Southampton or the Hamble, many of us locally have to chip off the crud.

Rob.
 
rob2 said:
I believe that exposure to fresh water is what causes a zinc anode to build up a white coating. As the water is not particularly saline either in Southampton or the Hamble, many of us locally have to chip off the crud.

Rob.
Click to expand...

Maybe worth trying aluminium anodes in place of zinc then. Equally suitable in salt water but more suitable in brackish water.
 
I was told as an apprentice that wire brushing anodes with steel brush could transfer steel particles to the anode as the brush wore down and that it could reduce the effectiveness of the anode? In any case there is no need to really do anything to the anode until it needs replaced.
I did once work for an ROV company offshore who insisted that the anodes on the cage system were wire brushed. They had occasional problems with corrosion which in my mind justified what I had been told as a cadet. I'm certainly no expert in metallurgy though.
 
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