Anodes

Sandy said:
Its a lot cheaper just buying a new anode.
Click to expand...

Your probably right but in this throw away generation I would get a kick out of making my own out of what would otherwise be waste material

Having just replaced the rear bearings on a car involving buying more tools in Portugal (I have them in UK!) A friend remarked it might have been easier and cheaper to just put it in a garage. Problem is I have the time and the capability and I enjoyed it!
 
Last edited:
NormanS said:
Written by a real Practical Boat Owner (not). :rolleyes:
Click to expand...

Roll your eyes as much as you like but these forums should be a place where people can get sound good advice on practical issues ........ Not the bad advice you seem to be so expert in giving
 
Sandy said:
Its a lot cheaper just buying a new anode.
Click to expand...

NormanS said:
Written by a real Practical Boat Owner (not). :rolleyes:
Click to expand...
Not sure how to take that. Do you have the kit to safely heat up a bunch of old anodes and cast new ones. If so fine, the majority of us don't nor know anybody who does. I'd be interested in the amount of energy it would take to melt 1 kg of zinc against the cost of buying a new anode.

Hey ho, I am just the son of a time served Clydeside marine engineer who had those skills, I've just got an engineering degree and a lot of practical boat ownership who knows their limits and it is not heating up lumps of metal.
 
Sailfree said:
I assume a plumbers lead melting pot would do on a propane gas ring?
Click to expand...

Not if it contains any traces of lead.

Maybe not if it is made of iron because you don't know the extent to which the molten zinc will dissolve iron. It appears from the phase diagram that the solubility of iron in molten zinc rises steadily from the melting point of zinc. (See below.)
Vyv , I believe, advises using a ceramic vessel

Fe-Zn-phase-diagram-for-stable-equilibrium-18-some-parameters-used-in-the-current.png
 
Iron dissolves readily in zinc (but to a limit of course). I'm not at all sceptical about the impurities issue.
In hot dip galvanizing we micro-alloy the zinc, and different galvanizers do this differently. Common elements to micro-alloy into the zinc are:
Lead: increases fluidity, dissolves to about 1% max, and the rest just sinks to the bottom. Typical level in zinc 0.5%
Bismuth: used as a replacement for lead, similar features, but expensive. Used by those who want to eliminate the use of lead.
Nickel: changes the reactivity of zinc and iron. Some steels of certain Silicon levels are quite reactive forming a thicker alloy coating on the item being galvanized. Ni modifies this rate (the rate is known as the sandelin Curve which could be googled for further info). Typical levels 0.01 to 0.05% Ni
Aluminium: used to produce brighter galvanizing (as people mistakenly think that shinier is better). Dissolves to many% if added, but in ordinary batch galv is typically 0.001%.
Iron: not wanted but gets there anyway as a result of the kettle (tank that holds zinc) slowly dissolves in its contents. These tanks are typically 50mm thick steel, and after about 10 years are down to 30mm at thinnest point. That's a lot of iron dissolved in the zinc. Even a steel ladle used in pouring some molten zinc into a mould for spectrographic analysis picks up some iron. This is what convinces me that melting in a steel vessel for anodes for boats would pick up some iron.

I tries an experiment last summer with a home made anode on my propshaft. Unfortunately no result as it fell off! I'll be trying again this summer. My anode was Zinc with 5% aluminium. Not the usual recipe, but a trial.

I think home made anodes are eminently possible, but with certain precautions about the chemistry of the zinc, and the influence of the equipment used to make them.
 
VicS said:
Roll your eyes as much as you like but these forums should be a place where people can get sound good advice on practical issues ........ Not the bad advice you seem to be so expert in giving
Click to expand...

As I said earlier in this interesting thread, I laugh in the faces of those poor unfortunates who have been brainwashed into believing that for a zinc anode to work, it must conform to the exacting requirements of some USA Military specifications. It's an eroding anode, for Goodness's sake. It gets eaten away. That's how it works.

I'm not advocating that anyone makes their own anodes, but the OP asked if anybody did, and I responded because I do make mine. I am a practical boat owner, and have built and maintained boats throughout my life, and have the practical ability to do all my own general maintenance, which in this particular case, includes making my anodes. Where's the bad advice?

Just a thought, did nobody else on here melt old bits of lead in a tin can, using a blowlamp, to make weights for fishing when they were younger? Making an anode from zinc is not that different, albeit at a higher temperature.
 
NormanS said:
As I said earlier in this interesting thread, I laugh in the faces of those poor unfortunates who have been brainwashed into believing that for a zinc anode to work, it must conform to the exacting requirements of some USA Military specifications. It's an eroding anode, for Goodness's sake. It gets eaten away. That's how it works.
Click to expand...

But as Vic's post#3 details, the presence of iron and maybe other elements passivates it. It may well appear to be doing something but the protection offered by a zinc anode containing iron may be totally illusory. All anode manufacturers produce to the same specification and I doubt that they keep these trace elements to a minimum purely so that they can charge extra money for the pleasure.
 
NormanS said:
As I said earlier in this interesting thread, I laugh in the faces of those poor unfortunates who have been brainwashed into believing that for a zinc anode to work, it must conform to the exacting requirements of some USA Military specifications. It's an eroding anode, for Goodness's sake. It gets eaten away. That's how it works.

I'm not advocating that anyone makes their own anodes, but the OP asked if anybody did, and I responded because I do make mine. I am a practical boat owner, and have built and maintained boats throughout my life, and have the practical ability to do all my own general maintenance, which in this particular case, includes making my anodes. Where's the bad advice?

Just a thought, did nobody else on here melt old bits of lead in a tin can, using a blowlamp, to make weights for fishing when they were younger? Making an anode from zinc is not that different, albeit at a higher temperature.
Click to expand...

Out of curiosity any opinions on whether you can melt the old anodes in an old SS saucepan. I have a number that don't work on induction hobs now!!
 
Sailfree said:
Out of curiosity any opinions on whether you can melt the old anodes in an old SS saucepan. I have a number that don't work on induction hobs now!!
Click to expand...

Sorry, don't know, but I doubt if it would get hot enough. I use a butane gas torch and an old iron ladle, enclosed in bricks. But as you can see here, the experts pour scorn on my methods. :D
 
vyv_cox said:
But as Vic's post#3 details, the presence of iron and maybe other elements passivates it. It may well appear to be doing something but the protection offered by a zinc anode containing iron may be totally illusory. All anode manufacturers produce to the same specification and I doubt that they keep these trace elements to a minimum purely so that they can charge extra money for the pleasure.
Click to expand...

Well Vyv, all I can say is that my home made anodes behave in exactly the same manner as the proprietary ones from Bruntons. They erode, and there are absolutely no signs of anything happening to the propeller, which is as new, after twelve years use (summer).
 
Sandy said:
Not sure how to take that. Do you have the kit to safely heat up a bunch of old anodes and cast new ones. If so fine, the majority of us don't nor know anybody who does. I'd be interested in the amount of energy it would take to melt 1 kg of zinc against the cost of buying a new anode.

Hey ho, I am just the son of a time served Clydeside marine engineer who had those skills, I've just got an engineering degree and a lot of practical boat ownership who knows their limits and it is not heating up lumps of metal.
Click to expand...

Yes, I have the modest equipment needed for melting a small batch of zinc.
Re the energy required, it is surprisingly little. Check out the specific heat of zinc, and also bear in mind that the anode in question is not 1 kilo, but a mere 1lb (454grams). I'm sure that someone with an engineering degree would be readily capable of calculating the energy required, making a guess about the efficiency of the system. Me, I just heat it til it melts.
 
I have melted lead to make weights for my home made don buoy using my handheld GAZ soldering burner.

My mold was s piece of stainless steel tube that became part of the weight.
 
Rogershaw said:
I have melted lead to make weights for my home made don buoy using my handheld GAZ soldering burner.

My mold was s piece of stainless steel tube that became part of the weight.
Click to expand...

I cast the weight for my lead line in a cardboard tube ( ex toilet roll) . Lead melts a much lower temperature than zinc though.
 
Rogershaw said:
You must have better quality loo roll cardboard tubes than we have.
Click to expand...

It would not have done a second one but was Ok for single use ... just!

It was over 40 years ago ... i guess in those days cardboard loo roll tubes where built to last. ...... People used to re-roll their own from the jumbo rolls in the works toilets ... until someone invented single sheet dispensing holders
 
You must log in or register to reply here.

Share this page

Top