Anode for outboard in freshwater.

[graham]

Im getting lazy in my old age and thinking of leaving my auxillary outboard permanently in the outboard well next season.

Intention is to protect the leg and prop with a few coats of epoxy ,also I intend to fit an oversize anode on the drive leg.

As the boat is mostly on a fresh water mooring what should this be made of?

 

[snowleopard]

Magnesium nm

nm

 

[alienzdive]

Re: Magnesium nm

Please correct me if wrong as I know very little about boats and fresh water....
It is my understanding that galvanic corrosion is a process that only occurs in salt water. I am under teh belief that anodes are not required in fresh water.

Zinc is the best anode reguardless, as it is less noble than other metals, ie lower down the periodic chart table. This makes it sacrificial and due to its relatively low cost, the best metal for use as an anode.

 

[snowleopard]

Re: Magnesium nm

There is certainly less electrolytic corrosion in fresh water but it still occurs. Because the salt content is much lower there are fewer ions to carry current. The voltage is still there however.

The reason magnesium rather than zinc is used is that it gives a higher voltage and is more effective in the more dilute solution.