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View Full Version : why magnesium for fresh and zinc for salt...



Tony
05-22-2003, 08:49 PM
As I searched for a magnesium anode (Boater's World has them...), I asked Canada Metal why fresh-water boats should use them. Here's their reply:

Because freshwater has a lot less chemicals (ions that you would find in saltwater)
and minerals, there is not the same amount of current that is flowing
through the water. Because of that Zinc needs quite a bit of current to
activate properly, and generally in freshwater your Zinc will not work at
all...several years down the road your Zinc will look relatively new
(providing you aren't in a "hot marina")
Magnesium is a super activated alloy which means that it can attract more
current through a less conductive environment such as freshwater, therefore
it will activate and protect your investment much more efficiently, and work
much like Zinc would in salt.
Basically, the less conductive environment, the more active alloy you want
to use, and vice-versa. Zinc won't work in freshwater, only Magnesium will.
Hope this helped.
Best regards,
Ty Seebach - US Martyr Sales

Greg Maier
05-22-2003, 09:56 PM
I heard that the best for salt is aluminum. I saw that in the Boaters World Catalog. Aluminum is upposed to be 40% more active than zinc in saltwater.

MOP
05-22-2003, 10:12 PM
I think they must be using 2S or nearly pure, no alloys to protect it.

mattyboy
05-23-2003, 08:02 AM
Tony,
what anode did you get the one behind the prop or the torque tab???? let me know if you have part numbers or mfg. names thanks.
BTW our boats are alot more alike, we found the holes for the windshiled on my boat so at one time it had a factory windshield on it but has since been removed.

Matty

penbroke
05-23-2003, 11:22 AM
mattyboy,
There is some info on this in the "saltwater props and other stuff" thread. The number I posted is for the one behind (ahead of?) the prop and I think it is zinc.

Frank

Tidbart
05-25-2003, 04:31 PM
Ok, I understand why the difference in materials for the different waters.
I have some questions though...
What would you run if you were in both types of water equally throughout the year??
Does it only matter when you leave the boat in the water for an extended period of time?
Would putting some zinc and some magnesium on the same drive help with this situation or cause other problems?

Bob