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Old 19 March 2003, 16:15   #11
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Strewth Manos don't tell the wife-I'm not allowed to be right!!!
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Old 19 March 2003, 16:20   #12
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Wavelength Join the club Mate!! LOLOL
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Old 19 March 2003, 16:54   #13
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Very sorry to hear of your misfortune Stuart. Nothing i can offer in the way of advice or help though i'm afraid.

While on the subject of anodes does anyone know about the diferance between freshwater and saltwater anodes? I beleive freshwater ones are magnesium and are eaten very very quickly by salt water but i've only learnt this through the grape vine! I also heard that conventional anodes arent much use in fresh water?
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Old 19 March 2003, 18:10   #14
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You weren't linked to shore power by any chance were you? Chained to a cleat that was connected to a separate earth?
Moored to another boat?

Both zinc and aluminium are sacrificial to steel, zinc first. If you have no, or not a lot of or have painted or antifouled the anode on the bottom of the engine mounting bracket then, by lifting the engine, you have removed the satrificial protection.
The aluminium casing must have been protecting something else. Do you have a SS prop? Remember, the metal does not vanish, it travels off to somewhere else. Not as bits of metal, of course.

Think carefully about how a circuit could be completed between the casing and some other metal further down the periodic table. (Usually iron - steel is iron+carbon so it'll do)

Food for thought, I hope.

If you feel you've solved it, let us all know.

JW.
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Old 20 March 2003, 01:40   #15
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Another Anode Question...if I may

Is it truth that if a boat comes out of the water for a period of time (say 1/2/3months) sacrificial anodes shoul be renewed (even if they are not perished) because they do not work once they come out of water??

This is something I was told in a chandler's shop where they wanted to sell to me sacrificial anodes for my engine.

Appreciate any advise as I never heard something like this EVER BEFORE!!
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Old 20 March 2003, 08:10   #16
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Hi folks

Sorry to here about this, sounds like it was quite bad.

A few thoughts of my own, while I am not well up on anodes I have had yachts for years moored in salt water.

1) Other boats would only cause you a problem if you was electrically connected to then, via shore power, mooring chains etc. If there is no electrical connection there should be no problem.

2) Do you keep your battery connected, if so i would start here.

3) Have you got copper based antifouling on the leg or boat.

4) Are the anodes which was underwater badly erroded?.

3) The amount of damage sound a lot for 5 weeks so I would think the stray currents must be quite big. If you read in I think last months PBO there was a case of a saildrive leg with similar problems and it gives you a few tips to check. If you cant get hold of a copy drop me a PM and I will scan and e-mail

4) Manos, as far a anodes, i think the only thing you need to do it the anode has been out of the water for a while is give it a good wire brushing to remove the oxides and show new zinc, I have never replced then each year just because they have been out fo the water.

5) Have a chat with MG Duff, they are on the web, they make anodes and if they dont know it it does not matter.

These are my thoughts, as i said i know a little but if any are wrong by people in the know please let me know .

Good luck

Regards Gary
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Old 20 March 2003, 08:20   #17
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Quote:
Originally posted by Garygee
....I think the only thing you need to do it the anode has been out of the water for a while is give it a good wire brushing to remove the oxides and show new zinc.......
This is exactly what I have been doing all this time. But the sodding salesman at the chandlers made me think I was not doing the right thing.
Thanks a lot for the info
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Old 20 March 2003, 08:25   #18
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Just another wee thought.
If you had one blade of a SS prop in the water, along with the aluminium gear case. The iron (SS)/aluminium/salt water would make a nice little cell.

I wouldn't wire brush the anode (iron particles). File it or sand it.

JW.
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Old 20 March 2003, 08:51   #19
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What type of honda is it. The honda 75 and the 90 have the same gear box / leg as a merc. Merc legs are oftern used on hondas becaus ethey are eaiser to get hold of and can be cheeper. This is why you sometimes see stripy hondas. Don't know wether this will help bring your bill down but 2k is a lot to have the leg changed.
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Old 20 March 2003, 10:17   #20
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Stuart
You definately have not got a normal situation here.
I know sod-all about the subject but I have had two boats, one with a Honda 75 and one with a Honda 130, PERMANENTLY afloat in a marina, each for over two years. The tips of the engines were permanently in the (sea) water and although they got filthy and fouled, they never corroded at all.
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