Anode replacement advice.

[bowler]

Hi all.

Just curious on thoughts. I have pulled my boat out today for the first time in 3 years due to C19 etc. It lives in freshwater, maybe 3 sea trips per year for a few days to a week or 2 ar a time.

I expected to have next to no anodes left on the hull but there is a load of them left. See pics. These have been on the boat for 4 years! Should I squeeze another year or 2 out of them? Interestingly enough, the trim tab anodes were nonexistent, but were significantly smaller to begin with I suppose.

Just curious as my previous boats lived on trailers and anodes were rarely changed at all.

 

[Parabordi]

Hi all.

Just curious on thoughts. I have pulled my boat out today for the first time in 3 years due to C19 etc. It lives in freshwater, maybe 3 sea trips per year for a few days to a week or 2 ar a time.

I expected to have next to no anodes left on the hull but there is a load of them left. See pics. These have been on the boat for 4 years! Should I squeeze another year or 2 out of them? Interestingly enough, the trim tab anodes were nonexistent, but were significantly smaller to begin with I suppose.

Just curious as my previous boats lived on trailers and anodes were rarely changed at all.

Those anodes are not doing anything.

You did switch from Zinc to Magnesium on the fresh water?

Zinc wont work inland.

 

[bowler]

Previous owner put them on before sale. I assumed Magnesium? Could be wrong. Have new magnesiums on hand if needs be.

 

[PeterBoater]

Also check the anode bonding wiring.

 

[Mark26]

I would disagree that they are not working. They are clearly, partly gone, looking closely at the zoomed pictures.

As it happens I’ve just taken my 30ft steel boat out of the water after four years and mine look similar. The boat is used mostly in fresh water and mine are magnesium.

Looking at the McDuff site, my boat needs two anodes and it actually has 5 in total, which may be why the wastage rate is low.

Four of mine are the same size as yours, the fifth is a pear shaped magnesium anode bonded to the bow thruster, and is the one which has the most wear, although I try to keep my use of bow thruster to an absolute minimum

Maybe Parabordi is used to much higher wastage rates on his boat?

I have changed all mine, but I do think they could have lasted a few more years.

 

[Mark26]

Have a look at the leisure catalog here:

MG Duff - Marine Anodes Technical Downloads, Comparisons, And More

 

[Mark26]

On the same subject, does anyone know if a Volvo Penta MD31A has an engine anode?
According to the Volvo manual, it does, but I can’t find it.

 

[Parabordi]

To the OP, get it checked before you incur a big bill.

 

[ctva]

Aluminium anodes are good for both fresh and salt water. Magnesium just fizz away when in salt.

 

[Mark26]

Aluminium anodes are good for both fresh and salt water. Magnesium just fizz away when in salt.

Indeed they do.

The obvious way for the op to see if his are working is to check for any signs electrolysis on the boat, if there is none and the anodes are showing wear, as they are,, then the conclusion is they are doing their job. The boat may be rarely plugged into a shore supply which would have an effect.