Recycling zinc anodes

Well, you are not actually protecting them unless they are connected with a cable to your hull, but they certainly create a few millivolts and these keep nibbling at your anodes until there is nothing left.

If the hull has no aluminum parts in the water you could use Al anodes and save a few $$, but zinc protects better because the voltage potential is higher. The conductivity of the water also plays a role.

 

There is something positive in this case! You have the proof they work correctly, sacrificing themselves!

Well said Cornelis!

Regards
Richard

 

A quick addendum because I was distracted and didn't finish the reasoning.

Taking stainless steel as a reference, the potential between ss and aluminum is approx. -.2 Volts, zinc gives over -1 Volt, so it is much more active. To obtain the same level of protection you would need 5 times the number or size Al electrodes, so cheap turns out to be expensive!

In clean, low conductivity water you could use Al because corrosion rate is low, in distilled water you need nothing at all.

Thanks Richard. I'll try not to get overconfident.

 

Up here, one used to be able to find aluminum everywhere for free (scrap) and it made sense. They are both expensive now ($1 lb.) but two savings are that, if you can get zinc without too much shipping cost, it will be far cheaper than buying zincs (Alaska/Hawaii, etc., more so), and people throw out slightly used zincs all the time.

 

A little more caveat on zinc smelter: http://chestjournal.chestpubs.org/content/101/3/862.full.pdf

 

..stick with the zincs, you already have them anyhow....

 

There's some good reading here too

http://www.boatdesign.net/forums/materials/blisters-around-zincs-steel-boat-23941.html

 

Wow, Hoyt - ought not breath it!