What anode type for Cardiff Bay?

[Bloater]

Hi, I am going to my new berth at Cardiff Bay and I was wondering what everyone there used for their anode material?

Is the water behind the barrier fresh water or is it regarded as 'brackish' these days?

I have an opportunity before my boat is launched to change the anodes. They are presently Zinc and very new.

Many thanks

 

[KJD]

Hi Quo
I have just relaunched my yacht. As the bay is fresh water I have used a secondary anode of magnesium which I can put over the side in the bay. They only last 21 days in salt water. Use link http://www.cardiffyachtclub.org/yachting/cruising.htm and look at the anode article

 

[Elza_Skip]

We use Magnesium on the drive and trim tabs.

These are ok for a few days at sea, however in the summer when we will spend 2 weeks in salt we wil swap them for the duration. Magnesium can over protect in salt and damage the paint

 

[Mike_S]

I've had aluminium for the last 12 months and changed them last night, about 50% worn. Am trying magnesium this time round as we only venture out into the sea for single days, rather than weeks at a time.

 

[Bloater]

My new boat is a sailing yacht and I will not be lifting the boat out and changing the anodes every time that I go on a cruise.

I hope that I will be out of the marina for more than 2 weeks every year so magnesium would seem to be a problem.

The boat will be on it's moorings for most of the time so Zinc seems to be a problem too.

Has anyone tried the aluminium based alternative?

If I use zinc and magnesium together (by dropping a magnesium anode over the side) won't the zinc and magnesium react?

It's a bit of a dilemma, can anybody else shed a light?

 

[PCUK]

I was based on a fresh water river and occasionally cruised salt water. Always used standard zinc anodes to protect the boat in the salt water. Fresh water is far less corrossive so shouldn't need any particular protection at all when in the bay!

 

[chrishelen]

Google MG Duff they will sort you out.

 

[tico]

Had the same prob afew years ago (my boat is berthed in brackish water) coz zinc ones tended to get coated with a layer of white chalky substance which prevented them from functioning to their full potential.
Spoke to MG Duff (theyre lousy at e-mail) and they recommende aluminium.
worked well, protecting outdrives, but it has to be the correct grade and v. expensive (2x price of zinc) but still cheaper than new outdrives

 

[wotayottie]

If you use zinc and magnesium together, the magnesium will in effect protect the zinc and will therefore go first.

If you are going to be at sea a reasonable amount then magnesium is no good - it will disappear quickly. I use aluminium which seems to be the best compromise. The zinc anode I have left on the boat simply gets covered in a white deposit in the fresh water and this stops it working altogether. No problem in my case. With bilge keels I simply dry out at somewhere like Combe, scrape off the anode, and go on my way.

 

[graham]

Some people are overcoming the problem by using anodes on a wire you can hang over the side. Reduces drag while sailing as well provided you dont forget to pull it in /forums/images/graemlins/grin.gif

 

[wotayottie]

Couldnt get that approach to work.

But then looking at the bottom of my boat when recently dried out in Combe, there was very liitle erosion of the ally anodes and no sign of any electrolysis. The zinc anode was covered with a thick white film. Thats alltogether much what I would expect - I dont leave the leccy plugged in when I leave the boat, and physical chemistry says that the electrolysis problem will be much less with a much lower level of salt in the Bay water anyway.

So in short, I reckon the issue is what anode can you use that will protect you when outside the bay without being made useless by being parked most of the time in fresh water. Ally seems to be the answer.