Anode Question

[swifty]

I am moving a boat fitted with Zinc Anodes, from a salt water environment to a fully fresh water environment, where the boat will be kept on shore power. Do I need to change the anodes and to what.

Thank you.

 

[dombuckley]

For fresh water use, you'll need to change to magnesium alloy anodes: same sizes and manufacturers, just unbolt the zinc ones and put the new ones on.

 

[VicS]

The MGDuff website might be worth a look.

Not sure whether a galvanic isolator is necessary in fresh water or not. The problems associated with leaving shore power connected should not be so severe but a GI might still be needed. Suck it and see perhaps.

 

[thompsoj]

There's less galvanic action in fresh water than salt water. Your Zinc will work just fine without change...that being said I'd clean the zinc up and re-echeck my connections due to the previous salt water use. Zinc's should be checked and cleaned every year regardless.

 

[VicS]

[ QUOTE ]
Your Zinc will work just fine without change

[/ QUOTE ] This is what the MGDuff website says about Zn anodes in fresh water:
Not all anodes are suitable for every environment, for example the surface of a zinc or aluminium anode will if left in fresh water for some time become covered with an off white crust of oxide which effectively seals the anode and stops it working even when returned to salt water. Zinc Anodes suffer a similar problem even in brackish conditions whereas Aluminium will continue to operate effectively in river estuaries and other areas of brackish water indefinitely. The consequences of this passivation of the anode are that the next most anodic item within the anode bonding system will start to sacrifice itself which could of course be very serious.

However it may be that no anode is actually needed in fresh water. In many cases they are probably fitted unnecessarily in salt water!

 

[moodymadness]

Change to magnesium alloy as stated above.

Pete