Is it possible to have too many anodes??

[huldah]

Re: Is it possible to have too many anodes??Ref: VicS

The magnesium anodes hang from each side of the wooden diving platform. One is clamped onto the rudder shaft, the other, via a brush, to the prop shaft.

With the connection being so good, I would think that it is almost as effective as fitting an anode directly onto the rudder. I particularly want to protect the rudder, as it had some corrosion when last lifted out. All steelwork was given a good coating of keel paint.

Philip

 

[Stoaty]

Re: Is it possible to have too many anodes??Ref: VicS

[ QUOTE ]
(please free free to check my arithmetic though

[/ QUOTE ] I trust your arithmetic is better than mine. It's been 36 years since my chemistry a level.

On the subject of anodes. I replaced mine in early august. I had one left over that was sent to me in error and I put it on the deck next to the gas locker. Meaning to put it away later. I noticed last weekend that it has started to corrode away. The deck is a ply/glass sandwich and the anode has not been in contact with anything else. It begs the question "would zinc anodes just corrode away naturally?" I shall compare it with the others next time I am out the water, but at this rate it might go before the ones in the water.

 

[tcm]

very good stuff vic. To sumarise for us yoghurt potterers, in a GRP boat it's fine have as many anodes as one fancies, short of sinking the thing with several tons of zinc??

 

[VicS]

Re: Is it possible to have too many anodes??Ref: VicS

[ QUOTE ]
It's been 36 years since my chemistry a level

[/ QUOTE ] Only 36! You should be able to remember a bit more of what you learnt at school than me then.


tcm [ QUOTE ]
in a GRP boat it's fine have as many anodes as one fancies

[/ QUOTE ] I kept awy from the original discussion because I don't really know. The risk perhaps would be lifting paint off iron keels or other painted metal bits underwater but I just think there would be no point in having a large number. They would all waste away at much the same rate as a small number I suspect, at least if they were actively protecting anything or suffering from the effects of stray currents in a marina + shorepower situation. Anything that is to be protected must have an anode close to it of course but to reduce the frequency at which it is necessary to replace anodes in a given situation then you would probably be better off fitting larger anodes. One which is twice as long , twice as wide and twice as deep will have a surface area 4 times as great (2 squared) but would have a mass 8 times as great (2 cubed) Since the ratio of mass to surface area is increased by a factor of two one might expect an anode 8 times the mass to last twice as long. That's not particularly attracive if it cost 8 times a much in the first place though but of couse haul out costs have to be taken into account.

What a load of hypothetical tosh. Make of it what you like. Write any comments on a postcard and burn them!

 

[Stoaty]

Re: Is it possible to have too many anodes??Ref: VicS

Well I have nine anodes. Two on each bilge keel, two on the rudder, two on the keel band and a bar for grounding, shaft etc. I get no problems. Anyone beat nine?