Aluminium anodes in Chichester Marina

[msimms]

After discovering my props are starting to dissolve I called Steel Development to see what the chances of repair were - negligible as it turns out. Anyway, during the discussion the very helpful person I spoke to said that in Chichester Marina; due to the level of fresh water that finds its way in to the Marina, an additional large aluminium bar anode should be attached to the transom. A wire should then be taken from this anode through the transom and be attached to the leg. This is of course in addition to the normal complement of zinc anodes.

Any Chichester marina residents tried this and were you pleased with results.

Cheers

Mark

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[tico]

I had a similar problems with a marina where its mostly fresh/brackish water and props suppering from electrolysis.

I fitted 2 aluminium anodes earlier this season, and so far they appear to have improved matters greatly.

Anodes had to be ordered specially from MG Duff and were about 4 times the price of standard Zinc ones. (Cheaper than a new set of props tho!)

<hr width=100% size=1>Been there, done that, got the oily T shirt

 

[pissativlypossed]

Are you sure they are advising Aluminium, the usual metal is Magnesium for fresh or brackish water. Magnesium is a more "noble" metal then aluminium and zinc and will therefore provide more protection then either, it will disolve at a much quicker rate though, so you may find yourself replacing them more often.
If the problem persists it would be well worth fitting a galvanic isolator you can buy them for about £80 and they are relativly easy to fit. They work by blocking low voltage leaking, below 1.2 volts which is what causes the battery effect of electrolysis, but it will allow mains voltage from shore power in the event of a short.

<hr width=100% size=1>"Open Another Bottle"

 

[tico]

No... deffo Aluminium
Zinc tends to get a white coating of oxide in fresh/brackish water which reduces its effectiveness.
Magnesium is OK for Fresh water, but in brackish with trips to sea water, I guess you could almost hear them fizzing away!

<hr width=100% size=1>Been there, done that, got the oily T shirt

 

[msimms]

That's what I was hoping to hear.

Did you fit the aluminium as a replacement for zinc or in addition?



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[tico]

In addition. They were the round ones about 1Kg each then connected to outdrive/props via a thick cable inside engine bay.

<hr width=100% size=1>Been there, done that, got the oily T shirt

 

[msimms]

Thanks for the tip, just ordered the parts required to knock up a galvanic isolator, £9.25 including post. Here's how to make your own <A target="_blank" HREF=http://www.yandina.com/galvanicIsolator.htm#DIY> galvanic isolator </A>.



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[gus]

It sounds as if MG are really ripping you off!! I have a 38' steel hull, use aluminium anodes and have no corrosion. If I bought the MG zinc anodes, each would cost nearly £30. Whereas I can buy 6 aluminium anodes from Jotun for about £35.

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