Alternative to anodes?

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rustyc

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Hello. I'm having a mobo which is in the sea brought inland for 2 years. It's coming round the coast in March and down the Trent to Nottingham. I understand that it needs the anodes changing from salt to fresh water, and back again in 2 years when she's taken back out to sea. As the boat will not be moved for the two years, can you use the internal earth wire trick to save having to change the anodes twice, or will the ones which are on it disintegrate in that time anyway?
thanks
 
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From my experience you'll be very lucky if your anodes last for 2 years, in any case.

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They should last inland well, they are rarely actualy required, its down to where you are. My Aluminium ones on my DP290's are on their 4th season now, thats with 6-8weeks salt water per year and the rest in fresh water, i normaly take them off and sandblast them clean before going to sea as the fresh water tends to lime them up a bit.
 
That's interesting, thanks. I'm used to having to replace ours - drying mud mooring - every 4-5 months. Look forward to saving a few quid when I get a decent boat on the Avon /forums/images/graemlins/smile.gif
 
Brilliant. Followed link, very helpful for someone with my limited knowledge. We'll just change them over to fresh and back again when permanently moving to salt.

Thanks
 
i normaly take them off and sandblast them clean before going to sea as the fresh water tends to lime them up a bit.

If your anodes have a scale over them it will stop them working, that's why they are lasting so long.

Aluminium is for Brackish and sea water, you should be using magnesium for fresh water.

You will get the same problem of scale on zinc anodes when you go into fresh water and it will stop them working too.

Sorry to be the bearer of bad news but you need to change the metal your using!

Tom
 
I changed the from Mag to Ali so I didn't have to swap when going to sea, the mag ones scaled up as well and needed blasting everynow and then also, the wear rate was the same, very slow. Ali is fine for freshwater, mercrusier recomend their Ali anodes for any all types of water.
I think the anodes you need are very particular to location and use but inland they are generaly not required, there are 1000's of boats on the Thames with none at all.
 
There are a few facts when it comes to boating, the most important of which is BOATS NEED ANODES!! unless that is if you keep your boat in a bottle of distilled filtered pure water which is highly unlikely.

Whether its salt, brackish or fresh water you will always get electrolytic action on metals below the water line. magnesium is best for fresh, zinc is best for salt and aluminium is supposed to be able to cope with all three. If anodes are lasting more than a year, either:

A) You have the wrong ones fitted

B) You have enough sacrificial metal bolted to the underside of your hull to sink the exxon Valdese

Whatever happens its always cheaper to replace anodes than stern gear, "P" brackets and props
 
Seems to be some different ideas, is there a hard and fast rule or do people do what they want to and almost anything works with varying degrees of success. Also been advised to dangle the correct anodes off the side of the boat when storing in fresh water and look for a certain voltage to ensure they're working. I'm calling MGDuff after 9am to ask their advise too. Will post later.
 
Blimey I have not got the wrong anodes, Ali or novalloy or whatever it is called (google Performance metal anodes) is perfectly suitable for freshwater.
Yes of course you need anodes if you have exposed metal fittings dangling in the water, but if all your metal is well painted and not exposed there will be little current flow through the water, fresh water does not conduct as well as salt. You need an Anode and a cathode to complete the circuit if one is missing or the wire (aka water) is a very poor conductor not much current will flow, hence the anode will not wear very fast. Mine don't wear very fast, fact, I and my family have had boats moored on the river for over 40 years and half the boats (admitably some were wooden with quality fittings) didn't even have anodes and experienced no problems.
This has drifted a long way from the original post, but the OP definately needs to change his anodes and keep an eye on them.
 
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