Anode choice

[Hillbilly]

Hi all,

I am after some input on anode selection. My knowledge in this area is limited!

I currently keep my boat on the upper Thames, but considering spending a few months next season on the south coast. I am aware of the need for different types of anodes based on FW/SW, but are there any materials that can tolerate both FW and SW and not fizzle away to nothing instantly?

Thanks all.

 

[mersey]

Aluminium is the best for both.

 

[Hillbilly]

Thanks Mersey

Any thoughts on how long Aluminium would last based on 50/50 FW/SW usage?

 

[Chris_d]

I'm upper Thames based and have done 2 months on south coast a couple of times, aluminium was fine and would certainly have lasted a lot longer. Thats with twin outdrives mind.

 

[Hillbilly]

Thanks Chris, good info. I'm on twin shafts, but guess the principle is the same. Did you find the Ali Anodes had good longevity in the FW as well?

 

[Chris_d]

I found the Ali ones do tend to corrode a lot in FW which makes them a pain to remove.
But they last a couple of years, a lot of places on the Thames you probably don't need anything.

 

[mersey]

Thanks Mersey

Any thoughts on how long Aluminium would last based on 50/50 FW/SW usage?

How long they last depends a lot on how big your anodes are, and how many of them you have, in relation to exposed metal parts that they are protecting.

Some people have painted A Brackets, P Brackets, rudders, others don't paint them, some boats have everything wired up to a couple of big anodes, some have seperate anodes on shafts or other parts.

But with the right balance, you can get a couple of years out of them.

 

[Leighb]

Interestingly there was an article in one of the mags recently - PBO I think - which said that the price of Zinc is now higher than Aluminium which in the past was much more expensive. Apparently it was the cost of Aluminium which meant it was used for seawater based anodes as Aluminium is better in both fresh and salt, but Zinc is unsuitable in fresh. Just a thought.

 

[mersey]

Apparently it was the cost of Aluminium which meant it was used for seawater based anodes as Aluminium is better in both fresh and salt, but Zinc is suitable in fresh. Just a thought.

Zinc is not suitable in fresh water it glazes over and doesn't then work. Magnesium is the traditional choice for fresh water, but fizzes in salt.

 

[Leighb]

Sorry meant to type unsuitable, typo, now corrected.