Rakicevic anodes, any good?

stuartwineberg

stuartwineberg

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Recently did my annual service bits shop at keypart who I think are a good outfit. Decided to buy my hull anode here instead of a Macduff from the chandlers and it is made by the company in the thread title who turn out to be Serbian. The price is certainly good but interested in anyone’s experience of them
 
stuartwineberg said:
Recently did my annual service bits shop at keypart who I think are a good outfit. Decided to buy my hull anode here instead of a Macduff from the chandlers and it is made by the company in the thread title who turn out to be Serbian. The price is certainly good but interested in anyone’s experience of them
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What is the specification of the zinc from which they are made.
It should be US military spec 18001, or similar.

[table="width: 600, class: grid, align: center"]
[tr]
[td]Cu[/td]
[td]Al[/td]
[td]Cd[/td]
[td]Fe[/td]
[td]Pb[/td]
[td]Others[/td]
[td]Zn[/td]
[/tr]
[tr]
[td]0.005[/td]
[td]0.1-0.5[/td]
[td]0.025-0.07[/td]
[td]0.005max[/td]
[td]0.006max[/td]
[td]0.1max[/td]
[td]remainder[/td]
[/tr]
[/table]

The low impurity levels esp, I understand, of iron are important and the cadmium content allows even this much iron.
 
VicS said:
What is the specification of the zinc from which they are made.
It should be US military spec 18001, or similar.

[table="width: 600, class: grid, align: center"]
[tr]
[td]Cu[/td]
[td]Al[/td]
[td]Cd[/td]
[td]Fe[/td]
[td]Pb[/td]
[td]Others[/td]
[td]Zn[/td]
[/tr]
[tr]
[td]0.005[/td]
[td]0.1-0.5[/td]
[td]0.025-0.07[/td]
[td]0.005max[/td]
[td]0.006max[/td]
[td]0.1max[/td]
[td]remainder[/td]
[/tr]
[/table]

The low impurity levels esp, I understand, of iron are important and the cadmium content allows even this much iron.
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Is this spec actually justifiable? I make my own (propeller) anodes, simply by melting down zinc from old discarded anodes. The zinc is melted in an old iron ladle. Obvious floating impurities are simply skimmed off the molten metal, but there may well be others hidden from sight. The anodes behave in exactly the same manner as bought ones. The only obvious difference being that mine only cost a few pence, as opposed to about £40 for the bought ones. Obviously, I'm not counting my time.
 
NormanS said:
Is this spec actually justifiable? I make my own (propeller) anodes, simply by melting down zinc from old discarded anodes. The zinc is melted in an old iron ladle. Obvious floating impurities are simply skimmed off the molten metal, but there may well be others hidden from sight. The anodes behave in exactly the same manner as bought ones. The only obvious difference being that mine only cost a few pence, as opposed to about £40 for the bought ones. Obviously, I'm not counting my time.
Click to expand...

Impossible to say without scientifically controlled laboratory testing and carefully monitored field trials

You could probably do some comparison trails by setting up a rig with a number of props of the same type fitting some with anodes guaranteed to confirm to the quoted spec, others with your home made anodes that will have been made from zinc which you have had analysed and by way of a "control" some props with no anodes.

Over a number of years you should be able to accumulate some interesting results. I am unlikely to still be around when you report your findings but I am sure there will be others just a s interested as I would be.
 
VicS said:
Impossible to say without scientifically controlled laboratory testing and carefully monitored field trials

You could probably do some comparison trails by setting up a rig with a number of props of the same type fitting some with anodes guaranteed to confirm to the quoted spec, others with your home made anodes that will have been made from zinc which you have had analysed and by way of a "control" some props with no anodes.

Over a number of years you should be able to accumulate some interesting results. I am unlikely to still be around when you report your findings but I am sure there will be others just a s interested as I would be.
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Except that I already know that mine work. I have used them continuously now for several years. They get eaten away, just like the bought ones, and there is absolutely no sign of propeller decay. What's not to like?

I should point out that for a few years, I did buy and use "official" anodes, and they behaved in exactly the same manner.
 
stuartwineberg said:
Must be a world record for thread drift! Anyone actually got an answer to my question based on their experience
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Sorry, but I was pointing out that provided they are made of zinc, one anode is as good as another. If you don't think tthat is helpful, feel free to ignore it.
 
stuartwineberg said:
Must be a world record for thread drift! Anyone actually got an answer to my question based on their experience
Click to expand...

Sorry

Just pointing out that to be guaranteed to be effective zinc anodes should be made of high purity zinc which conforms to the spec quoted, or similar.
Just being made of zinc of unknown purity is is not good enough.
My understanding is that the very low iron content is important if they are to be effective.

A little investigation reveals that the anodes in question are made of zinc that conforms to the US Mil spec quoted

I dont suppose anyone has done a sufficiently detailed study of their performance to be able to pass judgement.
 
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VicS said:
Sorry

Just pointing out that to be guaranteed to be effective zinc anodes should be made of high purity zinc which conforms to the spec quoted, or similar.
Just being made of zinc of unknown purity is is not good enough.
My understanding is that the very low iron content is important if they are to be effective.

A little investigation reveals that the anodes in question are made of zinc that conforms to the US Mil spec quoted

I dont suppose anyone has done a sufficiently detailed study of their performance to be able to pass judgement.
Click to expand...

Good to hear about the spec. Thanks
 
Melting zinc in a steel vessel is pretty sure to add some Fe to the Zn. Fe is soluble in liquid Zn, variable with temperature. At 419C (melting point) to about 460 its not bad, but get the Zn up to about 500 and bad things happen.
Without measuring it, it's almost impossible to know what temp the Zn gets to in a DIY anode situation. That doesn't mean it should not be done.
 
I suppose one could compare the effectiveness of home made anodes using a voltmeter, some different samples of seawater and various bits of metal?
 
An anode is merely a small lump of less "noble" metal than the metal that it is there to protect. I don't believe that in the real world, a little impurity in the anode is going to make the slightest difference. My home made ones work exactly the same as the ones that I used to buy. I have to replace my prop anode every year, because it gets eaten away, just as I had to replace the bought ones.
 
lw395 said:
I suppose one could compare the effectiveness of home made anodes using a voltmeter, some different samples of seawater and various bits of metal?
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It may not be that simple
Apparently the problem is passivation of the zinc over time. Presumably if the zinc is being consumed steadily the anodes are remaining active.

A little more info here https://boatzincs.com/use_milspec_a18001k.html
 
NormanS said:
An anode is merely a small lump of less "noble" metal than the metal that it is there to protect. I don't believe that in the real world, a little impurity in the anode is going to make the slightest difference. My home made ones work exactly the same as the ones that I used to buy. I have to replace my prop anode every year, because it gets eaten away, just as I had to replace the bought ones.
Click to expand...

Paraphrasing VicS' link, that is not what the USA military found. I do not deny that you have had success with your method but maybe they are looking for more than a year in service?
 
I suspect any anode becomes 'impure' when immersed in our harbour.
Even genuine ones can acquire something of a 'crust'.
I tend to abrade them whenever the boat's out for a scrub or when diving.
 
VicS said:
It may not be that simple
Apparently the problem is passivation of the zinc over time. Presumably if the zinc is being consumed steadily the anodes are remaining active.

A little more info here https://boatzincs.com/use_milspec_a18001k.html
Click to expand...

There must be an awful lot of anodes sold that don't comply. Just looking round the boatyard, almost every anode on every boat has a white crust on it.
 
NormanS said:
There must be an awful lot of anodes sold that don't comply. Just looking round the boatyard, almost every anode on every boat has a white crust on it.
Click to expand...
More likely they're used in water which doesn't comply?
Maybe the US Navy didn't do the tests in a soup of copper-based antifoul mixed with Hampshire mud?
 
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