What you gain on the roundabouts (anodes) you lose on the swings (shipping)!

[Fr J Hackett]

That was always my understanding as well...but things have changed

Electro chemistry hasn't changed since the days of Faraday as far as I am aware.

 

[Kwik Decision]

I'm sure Vyv Cox will be along to give chapter and verse, but in layman's terms modern aluminium anodes are not pure Al, they contain small amounts of zinc and other metals, which mean they have the same potential as pure zinc. Therefore they are as effective as zinc, and are intended to be used in salt water. For fresh water magnesium anodes are usually used.

I guess our understanding of electrochemistry has improved greatly since Faraday, hence the ability to produce mixed metal anodes of the desired potential.

Further info here:
Anodes

 

[rogerthebodger]

Electro chemistry hasn't changed since the days of Faraday as far as I am aware.

It hasn't it that there is little understanding of what electro chemistry is all about

You need 2 different metals (anode) and cathode) and electrolyte (sea water) and an electrical connection.

If any one is missing there will ne no electro chemical action.

On my steel boat all the metal in the sea water hull have a very close anodic potential with Zinc anodes but I have eliminated as mush electrical connections as possible with a well painted hull. This all reduces the anode wastage.

At one time the earthing of all underwater metal parts was a common action. This introduced am electric path thus creating electro chemical corrosion where non wouls take place

 

[PeterBoater]

I'm sure Vyv Cox will be along to give chapter and verse, but in layman's terms modern aluminium anodes are not pure Al, they contain small amounts of zinc and other metals, which mean they have the same potential as pure zinc. Therefore they are as effective as zinc, and are intended to be used in salt water. For fresh water magnesium anodes are usually used.

I guess our understanding of electrochemistry has improved greatly since Faraday, hence the ability to produce mixed metal anodes of the desired potential.

Further info here:
Anodes

Aluminium also for brackish water.

 

[Fr J Hackett]

It hasn't it that there is little understanding of what electro chemistry is all about

You need 2 different metals (anode) and cathode) and electrolyte (sea water) and an electrical connection.

If any one is missing there will ne no electro chemical action.

On my steel boat all the metal in the sea water hull have a very close anodic potential with Zinc anodes but I have eliminated as mush electrical connections as possible with a well painted hull. This all reduces the anode wastage.

At one time the earthing of all underwater metal parts was a common action. This introduced am electric path thus creating electro chemical corrosion where non wouls take place

You don't say

 

[Fr J Hackett]

I'm sure Vyv Cox will be along to give chapter and verse, but in layman's terms modern aluminium anodes are not pure Al, they contain small amounts of zinc and other metals, which mean they have the same potential as pure zinc. Therefore they are as effective as zinc, and are intended to be used in salt water. For fresh water magnesium anodes are usually used.

I guess our understanding of electrochemistry has improved greatly since Faraday, hence the ability to produce mixed metal anodes of the desired potential.

Further info here:
Anodes

Your understanding may have improved but the electrochemistry hasn't.

 

[zoidberg]

Er, thanks.

As a matter of fact, I wasn't seeking advice on how to leave the site, but drawing attention to what seemed like an unjustifiably high shipping cost tacked onto an apparently bargain price for the item.

I will try to make myself clearer next time.

I've just had a peek on Amazon.co.uk. There's a huge range of anodes on offer, and many offering cheap or FREE delivery.
I don't know if there's a similar pattern in France, but it'd be worth a look.

 

[vyv_cox]

I understood that aluminium anodes are suitable for fresh water and zinc for salt water. Happy to be corrected, but have been using zinc anodes in sea water for around half a century without problems.

Pure aluminium and the alloy used for aluminium.anodes have very different galvanic potentials. Article here Anodes