Which anodes

[the griff]

Sorry, I know this has probably been asked many times.
I have 24 foot fibreglass hull boat with a dp outdrive. The boat is trailered at the moment but will be going back in the river shortly. The river is upstream of the barrage so is freshwater. Although it will be kept on the freshwater I plan to venture out to sea for a couple of days at a time where we will be anchored in saltwater.
Do I go for freshwater anodes or saltwater anodes, or is there something that will do both?
I need to replace the anodes on the outdrive and the trim tabs.

Thanks in advance for any advice.

 

[omega2]

Talk to these people they may have solution for you.

http://www.zincsmart.com/

 

[VicS]

Sorry, I know this has probably been asked many times.
I have 24 foot fibreglass hull boat with a dp outdrive. The boat is trailered at the moment but will be going back in the river shortly. The river is upstream of the barrage so is freshwater. Although it will be kept on the freshwater I plan to venture out to sea for a couple of days at a time where we will be anchored in saltwater.
Do I go for freshwater anodes or saltwater anodes, or is there something that will do both?
I need to replace the anodes on the outdrive and the trim tabs.

Thanks in advance for any advice.

The rules are

Zinc is suitable only for salt water. It becomes coated in a passivating oxide layer in brackish or fresh water which remains even when returned to salt water.

Aluminium anodes are suitable for salt or brackish as it, like zinc, becomes coated with an oxide layer in fresh water

Magnesium is suitable for fresh water only as it is far too reactive for use in salt or even brackish water and will be consumed too quickly

There you have it but it does not answer your question.

Talk to MG Duff http://mgduff.co.uk They are the experts. ( Oh new website. I wonder where they have hidden all the useful info)

 

[MapisM]

Do I go for freshwater anodes or saltwater anodes, or is there something that will do both?

I don't think something as effective in fresh as in salt water has been invented yet, but for the usage you describe, I'd go for magnesium (fresh water).
They will wear a bit faster when used in salt water, but since the boat will spend most of her time sitting in fresh water, that's where you want the best protection.
Don't forget to check if there are anodes also inside the engine somewhere (you might ask volvopaul, if as I understand it's a VP engine).

 

[Momac]

Aluminium anodes are appropriate for mixed fresh and salt water use.
http://www.solentanodes.co.uk/collections/sail-sterndrive-aluminium-anode-kits

..

 

[rafiki_]

The folk that I know that moor at Penarth, in fresh water, use mag anodes, despite their ventures to sea. Mag is the answer for you. If you can buy them in the USA, they will be much cheaper than here.

 

[aquapower]

Talk to MG Duff http://mgduff.co.uk They are the experts. ( Oh new website. I wonder where they have hidden all the useful info)

I was trying to identify an anode a few days ago and was disappointed with the new website, bring back the online catalogue, like you say, all the useful info has gone.

 

[the griff]

After loads of reading and research I think I may of found an answer.

http://www.force4.co.uk/performance...t-volvo-penta.html?sqr=Navalloy&#.VsI3OEXfWnM

Thanks for the input, but these look like the best all round solution.

 

[MapisM]

Mmm... Anodes claiming a "Longer Life: upto 30% to 50% greater than zinc and 5 times that of magnesium"
The last thing I expect/want from my anodes is to be longlasting, FFS!

That said, the boat is yours, and as long as you're happy we're all happy! :encouragement:

 

[pondfish]

I bought my boat from down west wales so when I brought it up to Cardiff bay I changed the anodes I put aluminium on rudder and skeg but put magnesium on my engine earths below water line on stern
its been 18 months now and I can see that magnesium has been working by getting smaller so im happy with that so when it comes out this or next month I will be renewing all with magnesium
I have done over 50+ days at sea so magnesium don't just fizz away