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Thread: Sacraficial Anodes

  1. #1

    Default Sacraficial Anodes

    So with the new boating season coming and everyone getting ready for the first big trip in the next month or so, How many of you guys have replaced all the Zincs on your Aluminum boat hulls and your outboards and your outdrives and your trim tabs. Those zincs are supposed to be replaced every couple years. And just because they look whole, they tend to rot from the inside out and quit doing their job. So don't let a little thing like that turn into big problems.

  2. #2
    Member hoose35's Avatar
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    Default

    I just ordered a set for my sterndrive and my engine yesterday. It has been 2 years since they have been replaced. They still look decent, but you are right, it is something that should be replaced every couple of years, not that expensive and easy to do.

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    I did not know an Anode can be eating from the inside out, interesting.

    If an anode is not being consumed it may not be electricity connected to the boat/engine.
    Measure the resistance from the Anode to boat/engine to make sure you have a good connection.

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    Default measure resistance?

    And how does one measure the resistance of the anode?

  5. #5

    Default #1 to long engine & drive life

    The anode is the material that actually gives itself up as marine corrosion takes place. You may have noticed people with zinc anodes mounted on the stainless steel trim tabs on their boats. In many cases, people think Zinc is always the best material to use for an anode. This is not necessarily true. The materials must be matched with regards to the potential between the anode AND the cathode. Zinc makes a very good anode when coupled with aluminum, however in the case of stainless steel a piece of standard angle iron is a much better option. The reason for this is that the potential between stainless steel and zinc is so great that the zinc actually sacrifices itself too fast and will actually create a problem.
    Elements necessary to accommodate marine corrosion. The first of which is the ANODE. The anode is the material that actually gives itself up as marine corrosion takes place. You may have noticed people with zinc anodes mounted on the stainless steel trim tabs on their boats. In many cases, people think Zinc is always the best material to use for an anode. This is not necessarily true. The materials must be matched with regards to the potential between the anode AND the cathode. Zinc makes a very good anode when coupled with aluminum, however in the case of stainless steel a piece of standard angle iron is a much better option. The reason for this is that the potential between stainless steel and zinc is so great that the zinc actually sacrifices itself too fast and will actually create a problem. I think this is where the electrical measurement takes place. If there is a lot of resistance the connection is good, if itís poor not enough metal to metal is taking place. ?

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    Member Bullelkklr's Avatar
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    Default just guessing but

    wouldn't poor resistance be a lot of resistance ? Little resistance is good continuity. The less ohms the better the connection.

    You would measure with an ohm/continuity meter. Put one end on the anode and the other on the location where you want to check continuity (motor block).

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    Bullelkkli:

    I wonder about the same thing, because it did not make sense. I went over to a friendís boat shop and measured the resistance from the anode to the Alum hull. After cleaning off the corrosion the resistance was .01 ohms.

    I think we are miss-interpreting what alaskapiranha is saying.

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    Default measuring resistance

    If I understand this correctly, the higher the ohm reading the more electricity therefore better connectivity resulting in more sacrifical anode which is good. Man thats a brain teaser. Sounds as if one can generate too much connectivity, does anyone really know what the ideal ohm reading is? Also, I have always been lead to believe that there should be one square inch of anode for every linear foot of the boat. For example I have a 26ftr so I have 26sq inches of anodes. What are other opinions?

  9. #9
    Member Bullelkklr's Avatar
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    Default No.

    The higher the ohm reading the more resistance - the more resistance the less voltage (if you are trying to push voltage through it).

    ie. 10 ohms is more resistance than 1 ohm.

    A dead short is 0 ohms.

    An open is mega-ohms or infinite resistance.

    If you meter a single copper 12ga wire of say 1 foot long it will have close to zero resistance; if you cut that same wire in half with a pair of dikes it will have infinite resistance - ie. no connectivity/conductivity.

  10. #10

    Default Copyed of Web Site

    I was just checking into replacing mine when form popped up. And I had copied that. didn't keep web site name. But it was not just some one writing it was a school or company who did. Wish I had kept.
    But I'm replacing mine after reading it.

  11. #11
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    Alaskapiranaha, is this what your looking for?

    http://www.perfprotech.com/store/art...sion-tips.aspx

    I could not find any reference to 1 sq inch per linear foot for the proper amount of zinc.
    With all the information I have it does not make sense.

    I personally would not replace all my zinc, if I wanted to make sure my boat was protected. The only way to guarantee you are protected is to do a corrosion survey on your boat. In 02 I decided I needed a forth job and learned how to do corrosion survey on boats.

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