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Thread: Different Anode Alloys

  1. #1
    Join Date
    Jan 2009
    Harrisville, Utah

    Default Different Anode Alloys

    Do you know the type of anodes used on your outdrives, outboards, boat hulls or propeller shafts?
    Mine came with zincs since its primary fishing was salt water before, which is recommended in those conditions and I have replaced them with new. My propeller trim tab was completely worn down to a small shark tooth shape point and the main motor zinc was heavily pitted. Been thinking about replacing them again with another alloy for the type water we are boating in.

    Zinc Anodes-Mil-Spec(A-1800K) zinc anodes provide excellent corrosion protection for outboards operating in salt water.

    Aluminum Anodes- Mil-Spec(A-24779(SH) aluminum anodes are slightly stronger than zinc and are an excellent choice for corrosion protection of outboards that operate in a mix of fresh and salt water, or outboards in salt water that are galvanically isolated from their neighbors at dock.

    Magnesium Anodes-Mil-Spec(A-21412(SH) magnesium anodes are designed to provide superior corrosion protection for outboards operating in fresh water only. They are the strongest anodes available and should not be used in salt or brackish water.
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  2. #2
    Join Date
    Jul 2008
    Cache Valley, Utah


    Good advice, Roger. As you noted, and a reminder to all, many outboards have more than one anode, if you go replacing be sure that all in the galvonic circuit(s) are same else only the strongest will be sacrificial (at least until it degrades).
    Last edited by smokepoles; 07-15-2021 at 06:11 PM.


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