not just Carvers-- any aluminum stern drive: google BOATUS SEAWORTHY GALVANIC CORROSION for a very good article; "..Sometimes sacrificial anodes can't get the job done. This could be because the differences between the voltages of the anode and cathode (the metals to be protected) are too close or because the area to be protected is large relative to the boat. In these cases, impressed current systems measure potentials in real time via a sensor, and a non-sacrificial anode emits adequate current from the boat's battery to protect the metals connected to the system. Aluminum sterndrives are a good example. In the early years after they were introduced, many had serious corrosion issues. Today, to supplement the protection from sacrificial anodes, the Mercury Marine sterndrives are protected by the Mercathode systems and Volvo uses the Active Corrosion Protection (ACP) system..."
Excessive zinc relacement
- Thread starter FriscoRon
- Start date
Here is why I'm thinking aluminum
http://www.cruisingworld.com/how/zinc-and-aluminum
I'm in brackish water with no aluminum in the water.
Ken
Ken
I am getting to be an aluminum fan especially in moorages like Everett. As you know I am very interested in continuing to study data and opinion from other folks but your link to the article does not work so can you outline your preference for us?
Charles
I am getting to be an aluminum fan especially in moorages like Everett. As you know I am very interested in continuing to study data and opinion from other folks but your link to the article does not work so can you outline your preference for us?
Charles
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Notice I did not say not to use aluminum. I merely stated to be sure of what you are doing if you use it. Chief
Sorry about the bad link. Here it is this time not from my phone.
http://www.cruisingworld.com/how/zinc-and-aluminum-sacrificial-anodes
Ken
Ken: Very well written article. My only precaution not emphasized, is be sure you have no other aluminum in the water if using aluminum anode! For example, I use an aluminum outboard motor propeller and if it were less noble than the aluminum anode it would be the primary sacrificial unit. If prop is more noble it still may pit some.
Nice discussion, Chief
Nice discussion, Chief
This discussion reminds me of the demo I used to do while teaching Electronics at Great Lakes Naval Training Center. I of course drank much coffee each morning . I would set up a multimeter with a penny on one lead clip and nickel on the other. To get the students woke up and involved I would drop the coins into my coffee. Their eyes would light up when the meter needle started climbing!
Now you have them! Start the discussion! Chief
Now you have them! Start the discussion! Chief
Aluminum anodes are frequently used and are often being required as a warranty condition by manufacturers.
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Fstbttms: Your point is well taken but being careful is my primary caution as what I stated is still valid. Manufacturers do not know what metals your boat has in the water. Chief
Understood. Just pointing out that the use of aluminum anodes is becoming more and more common.
Chief -
I am confused here. So far I cannot find any aluminum alloy used by a manufacturer in castings or sheet goods that has a negative potential greater than the MilSpec alloy of either zinc or aluminum anodes.
The metal to be protected does not care what the protective anode is made from does it? All the protected metal needs is an anode that is more active - one that produces a minimum negative shift.
For example, if the metal to be protected needs a protective anode alloy that will produce a minimum negative shift of 100 mv then how can a negative shift of 200 mv (aluminum) pose any threat compared to zinc at 150 mv?
Can you tell us exactly what is the risk of an aluminum anode manufacturer not knowing what underwater metal is being protected - so long as the anode foundry product meets MilSpecs?
Charles
The mil specs you are using relates to the sacrificial capabilities of the substance so if your going that technical then you can analyze which metal is the least noble and it had better be the anode. Personally, if I had aluminum in the water, which I have, I would not use an aluminum anode. If I had NO aluminum in the water then I would lean toward using the aluminum anode Thats up to you and you obviously have the ability to analyze substances properly. Chief
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Back on track: with all this discussion generated, it would be reasonable to assume that Ron could probably use aluminum anodes as he has a sailboat that likely has no aluminum underwater anyway. As fstbttm has pointed out more aluminum anodes are presently being used. Chief