Zinc or ali anodes

but the alu will decay faster I think. I'm no expert but was under the impression that it's basically magnesium for fresh water, zinc for salt and Alu as a compromise. for the sake of £20 you might end up best case having to replace it sooner, or worst case making a mess of your prop etc.

M G Duff are quite helpful if you give them a buzz.
 
Not necessarily. Mercruiser now provide all their outdrives with Ali anodes for seawater use, after they had problems with corrosion with Zinc anodes.
 
Oh dear lets get it right.

Salt water: zinc OR aluminium

Brackish water: aluminium

Freshwater: magnesium.

For salt water use aluminium is expected to last about 1¼ times as long as zinc. aluminium anodes are also less expensive than zinc ones

Loads of useful info on the MG Duff website
 
I was advised by mercruiser service dealer that if I did not use mercruiser parts then I could have a problem with any warranty claims, so be careful when using the likes of McDuff
 
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