Anode Choice

[Dino]

I’m based on a freshwater inland waterway but I’m planning to go to sea for three months this summer.
I replaced my anodes with the standard inland Magnesium anodes last summer.
I’ve read up on this a bit and it seems that I should have zinc for saltwater.
I will lift the boat before I go to sea this year for a quick wash and antifoul. Should I fit zinc?
I will probably lift my boat in November for the winter. Will I be okay leaving the zinc anodes on from August to November on freshwater?

 

[Anibal]

Why not fit Aluminium instead? My previous boat was in brackish water but I used to go to the sea on the Thames/Medway coast and fresh water on the non tidal Medway all the time and never had any issues or corrosion on my outdrive or trim tabs.

 

[Tranona]

Yes, aluminium will do both fresh and saltwater

 

[Momac]

I keep my boat on fresh water with occasional salty water trips in the summer.
I have used Aluminium anodes over the last decade and have no corrosion issues. The anodes could last several years but I replace them every two years . I am just now changing the anodes and almost tempted to clean up and re-use the removed anodes but on the whole I consider new anodes a good investment.

But the first thing is to find out in your case is whether aluminium anodes are available to suit your boat.

I would not be too worried about corrosion on the boat with zinc anodes on fresh water for a few months. However the zinc anodes may develop a passive coating which may mean they will not be effective when the boat is next on salty water.

 

[Dino]

Thanks folks. I’ve seen some conflicting information online so I was looking for some personal experiences. I’ll get some aluminium anodes and fit them before I head out to the salty stuff.

 

[ducked]

There are apparently problems getting some anodes, prop shaft ones of specific sizes, for example, in Al, which can stop you using them altogether, since the advice is not to mix them, since they interact. Im unclear why this is supposed to be a problem.

Im also unclear whether this prohibition extends to internal anodes like the one in my salt water cooling system, though I presume so.