Anodes again

[Lightwave395]

Apologoies if this is previously covered - I can't find anything at the moment - I keep my boat in fresh water but sail in salt water. Should I have an aluminium or a zinc anode ? Here's a pic of my 15 month zinc anode when the boat was lifted last saturday after 12 months in salt water and 3 months in fresh . I've read the anode page of Mr Cox's excellent website and am leaning towards aluminum at the moment ?

 

[dombuckley]

Changing to aluminium seems sensible. In fresh water, zinc quickly develops a chalky oxide which prevents further action, even after returning to salt water.

 

[Tranona]

Aluminium. Better in fresh and now becoming the norm in seawater as well. Volvo have changed over to aluminium totally. The potential of the alloy used is virtually the same as zinc, but lighter and cheaper to make 9not necessarily to buy!)

 

[Aja]

I have a shaft anode and pear anode, both zinc. I replace the shaft anode every year and the pear anode when required.

Next season, can I put a cheaper aluminium anode on the shaft while retaining the zinc pear anode, or is it not advisable to mix metals (alloys)?

 

[vyv_cox]

I have a shaft anode and pear anode, both zinc. I replace the shaft anode every year and the pear anode when required.

Next season, can I put a cheaper aluminium anode on the shaft while retaining the zinc pear anode, or is it not advisable to mix metals (alloys)?

Nobody has tested this to my knowledge. Difficult to theorise but the potential of each is very similar, details on my website. Give it a go and let us know: the worst that can happen is one anode will be wasted preferentially.

 

[Aja]

Nobody has tested this to my knowledge. Difficult to theorise but the potential of each is very similar, details on my website. Give it a go and let us know: the worst that can happen is one anode will be wasted preferentially.

My prop won't go fizzle?

 

[Tranona]

My prop won't go fizzle?

No. Your comment that you change your pear anode when required suggests it is not doing much. Assuming it is bonded to the shaft to protect the prop this is to be expected because the shaft anode being closer is doing all the work.

 

[vyv_cox]

My prop won't go fizzle?

No, if there is any potential between the anodes, which is unlikely, one will waste preferentially but your prop will be protected as it is cathodic to both.

 

[Aja]

Thanks for the confirmation. I'll give it a try next season and report back in a year or so.

Just don't like being a pioneer, that's all