Used anodes

[VicS]

If the OP has not already done so, has he thought of fitting a galvanic isolator that ought to slow anode erosion.

Only if he leaves the boat connected to a shorepower supply for much of the time and only if the shorepower earth is bonded to the DC negative/hull anode.

In any case the 25% loss of hull anode is nothing to worry about... unless it has lost that much in significantly less than a season...... It should last a good while yet. There is no need to replace it until it has lost nearer 75%.

Sail drive anodes are a different kettle of fish. They must be replaced if down to 50%.
However, they should not come into the shorepower/ galvanic isolator equation. At least not if the sail drive is isolated from the engine.

 

[PTB]

Hang the old anode over the side for the winter ( if youre afloat !) on a wire to a crocodile clip to the engine , or prop shaft if you prefer. This will save wastage on your new anode. Phil

 

[VicS]

Hang the old anode over the side for the winter ( if youre afloat !) on a wire to a crocodile clip to the engine , or prop shaft if you prefer. This will save wastage on your new anode. Phil

The OP has sail drive ! Connecting a hanging anode to that could be worthwhile while afloat and a good use perhaps for a partially depleted hull anode

We do not actually know what his hull anode is connected to and intended to protect!

 

[vyv_cox]

Vic, if you use SS studs, won't they corrode the thing they are supposed to protect in a case like this?

Carbon steel studs corrode most after the boat has been lifted. Stainless ones won't do this. Both are well protected by the anode when they are immersed.

 

[mdonnelly]

Dont know what a galvanic isolator is! Got a new engine installed last year. Engineer fitted the hull anode and the two bolts are connected to the engine. Previous saildrive was a volvo 120s. It had a large saildrive anode and two small anodes on the prop. New saildrive only has single anode.

 

[VicS]

Dont know what a galvanic isolator is! Got a new engine installed last year. Engineer fitted the hull anode and the two bolts are connected to the engine. Previous saildrive was a volvo 120s. It had a large saildrive anode and two small anodes on the prop. New saildrive only has single anode.

Oh dear.

A galvanic isolator is a device that should be fitted in the earth connection of a shorepower installation.
It blocks current from low voltage sources, such as dissimilar metals, which can cause galvanic corrosion but allows current from high voltage sources to flow thereby maintaining the safety aspects of the earthing.

What is the new sail drive. Most have an anode on the drive leg and another on the prop .

What is the new engine for that matter.

What other metal underwater fittings are there. Are any of them connected to the engine or the DC negative.

Your hull anode may not be doing anything at all. Just sitting there slowly corroding on its own.

 

[GrahamHR]

I have never understood the function of a hull anode on a non metallic boat. Unless it's connected to something metallic, then it's doing nothing. If there's something metallic to protect, isn't it better to fit the anode directly to it?

 

[VicS]

I have never understood the function of a hull anode on a non metallic boat. Unless it's connected to something metallic, then it's doing nothing. If there's something metallic to protect, isn't it better to fit the anode directly to it?

Commonly fitted to protect the stern gear .. it is not always possible to fit a shaft anode and their use is not without pitfall even when they can be fitted.

Frequently fitted completely unnecessarily.

Poor bonding via the gearbox and shaft may render them ineffective.

Sometimes even fitted and not bonded to anything!

However "They" lead us to believe that anodes are vital.
Once fitted, necessary or not, effectively bonded or not, everyone, especially the anode manufacturers, is happy.

 

[SHUG]

Hang the old anode over the side for the winter ( if youre afloat !) on a wire to a crocodile clip to the engine , or prop shaft if you prefer. This will save wastage on your new anode. Phil

I often thought of doing that properly by melting the old anodes down, moulding a cylinder and fusing in a length of wire rope to do a proper job.
BUT I was put off by scare stories.

Has anybody cast zinc or got a sensible article on how to do it.?

 

[barnaclephill]

Has anybody cast zinc or got a sensible article on how to do it.?

Attached are both my PBO article scans on the subject. They are in full resolution at:
http://s1136.photobucket.com/albums/n491/barnaclephill/

 

[mdonnelly]

VicS, saildrive is a Seaprop 60 attached to a 20HP Beta. I Have shore power but only use it several times a year. The sail drive has a single circular anode between drive and propeller hub. The hull anode is near the saildrive and there are two wires internally attaching fixing bolts to the engine.

 

[Tranona]

VicS, saildrive is a Seaprop 60 attached to a 20HP Beta. I Have shore power but only use it several times a year. The sail drive has a single circular anode between drive and propeller hub. The hull anode is near the saildrive and there are two wires internally attaching fixing bolts to the engine.

That anode is not doing anything as there is nothing for it to protect. The engine has an anode in the heat exchanger which does need regular checking. The engine will also be insulated electrically from the saildrive, which as you know has its own anode.

 

[VicS]

VicS, saildrive is a Seaprop 60 attached to a 20HP Beta. I Have shore power but only use it several times a year. The sail drive has a single circular anode between drive and propeller hub. The hull anode is near the saildrive and there are two wires internally attaching fixing bolts to the engine.

Thanks. I had a quick look at the installation instructions, but did not learn the things I wanted to.
I thought that perhaps it wasn't but if Tranona is right and the sail drive is insulated from the engine the hull anode, as he says, is not doing anything.
For it to supplement the saildrive anode there must be a good electrical connection from it through to the sail drive leg. Something you could investigate with a multimeter.

Whether or not the prop has an anode depends on the prop. Many do, some dont.

Be sure to replace the saildrive anode before it is totally depleted. Once thats gone the leg itself starts to go, but you know all this already.

As Mr T says there is an anode in the engine heat exchanger that will require regular replacement.

If you should ever leave your shorepower connected ( not necessarily in use) you must investigate the galvanic isolator issue. The shorepower earth should , according to current wisdom, be bonded to the DC negative although it may not be. If it is then the GI is next to essential.

 

[mdonnelly]

Thanks for advice. Engine now on its 3rd anode since last Feb when it was installed.

 

[electrosys]

Attached are both my PBO article scans on the subject. They are in full resolution at:
http://s1136.photobucket.com/albums/n491/barnaclephill/

Interesting articles - but it is not mentioned that anodes recycled using such methods will be less effective than the originals, due to an increased level of dissolved iron originating from the steel crucible/ ladles used.

To avoid such contamination, simply use a ceramic crucible to melt the zinc and pour into a non-metallic mould straight from it.

Also - if the anode feedstock is contaminated (it probably will be) it would pay to make up a simple chloride flux to help separate the dross during melting. The use of a flux covering will also allow higher temperatures to be reached without the inconvenience of ZnO fuming.

These are just two of the more basic precautions taken in commercial zinc recycling.

 

[alahol2]

Thanks for advice. Engine now on its 3rd anode since last Feb when it was installed.

If you are using Beta anodes, speak to zincsmart. Much, much, much cheaper.

Only a customer etc...

 

[mdonnelly]

If you are using Beta anodes, speak to zincsmart. Much, much, much cheaper.

Only a customer etc...

Just ordered 6 at slightly cheaper cost than the 2 I bought from the beta engineer. Thanks for that.