[Doug Odgers]

I need to renew the anodes on A90’s rudder.

It seems the blade is made of aluminium.

Does this require any special anodes  or is the ‘bog standard’  zinc laden sufficient?

Topic

[AOA]

Doug

I think you want a magnesium anode rather than the more usual zinc. They make themy specifically for aluminium rudders as large diameter profiles discs. Ed.2/6/21 This response is incorrect, with apologies, as magnesium is freshwater use only. Large disc zinc anodes should be used.

Available from lots of places. E.g Force 4 

Cheers
Nick

[Dominic Dobson]

I thought magnesium was for fresh water use I used standard zinc discs on A90 when I had her

[Doug Odgers]

Nick,

Thank you for your excellent advice.

Good job I asked !

 

Doug

[AOA]

Oh dear, I am really sorry to have misled you Doug. Dom is absolutely right. I allowed myself to become confused having just fitted magnesium to a boat on the broads. Looking again at photos of Helene’s rudder anode the apprear, as Dom says, standard zinc.
I have edited my original erroneous reply to avoid misleading anyone else in the future.
Many apologies
Nick, on the naughty step

[Author]

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