External wire?

guydickinson

guydickinson

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I have this anode on the skeg of my boat (have mentioned it before), UNattached electrically to anything. It is inherited from the last owner. Its a bit pitted - must be natural corrosion and not electrolytic? Anyway it is about 3 inches from where the stainless rudder stock pivots at its base and there are nuts on the fitting there. Is there some sort of external wire available to connect the two? Might as well (or should I leave well alone as nothing has been electrolytically affected as yet!!?). I invisage some sort of flat copper strip but not sure if that sort of thing is available?? Could make it if not - if a good plan. Thanks.
 
I Have heard of some people who earth their lightning protection through a copper strip/braid and bring this to the surface of the subsurface skin onto an anode.

A bit OTT but its worth checking underneath for a strip or braid.
 
As I understand it your anode does'nt actually need to be bonded by wire...just to be in 'line of sight' and nearby will also do the job.

Regds Nick
 
[ QUOTE ]
As I understand it your anode does'nt actually need to be bonded by wire...just to be in 'line of sight' and nearby will also do the job.


[/ QUOTE ] An anode must be electrically connected (bonded) to the item(s) it is to protect. The expression "line of sight" need not be taken too literally but it must be reasonably close to what is is to protect and not shielded from it.

[ QUOTE ]
I invisage some sort of flat copper strip

[/ QUOTE ] That cannot be outside the hull .ie in the water. Copper in the water connected to the anode will cause it to corrode very quickly.
 
Get a multimeter and check the resistance between the anode and the metalwork of the rudder/skeg. If there is no connection there will be no protection. As said above, and external copper wire will be worse than useless but a s/s strap (of A4 or 316 stainless) would do the job.
 
Vic...Are you saying that it must be bonded, AND more or less 'line of sight'.

( On my boat I have some items that are bonded and some not )

Regds Nick
 
Yes the anodes MUST be bonded with a good low resistance connection to the items they are to protect. Except when the anode is mounted direcly on the item such as on a steel rudder, bilge plate, keel, propshaft etc that means via internal wiring.

I do not want to re-ignite the argument about "line of sight" but the anode must be close to what it is protecting which means large areas will require two or more anodes and there must be a fairly direct route through the water. The curvature of the hull will not shield it but a rudder blade for example will probably need two anodes so that one can "see" one side of the blade and and the second can "see" the other.

If you have any anodes that are not bonded to anything then they are not doing any thing useful and if you have no signs of corrosion that might be prevented by them they are not necessary. Similarly any underwater fittings that are not bonded to an anode or anodes are not being protected. If they are not showing any signs of corrosion then they do not need to be protected. Bronze skin fittings should not normally need protection for example. I am very doubtful if in the majority of cases shaft anodes are actually necessary as well. IMHO anodes should be fitted to solve an observed problem rather than fitted in case there is a problem. The Berwick I sail has no anodes at all. The prop, the shaft and all the skin fittings are original (from circa 1977) and there is no significant rusting of the keels which have never been repainted other than with A/F.
 
Thanks - fascinating. Well I guess I just don't need an anode then. I believe it was put on by a boatyard 2-3 yrs ago. I guess they were asked to put one on and literally did just that - job done!...but not connected! Quick extra point: Does such a solitary unconnected anode do anything to protect you from other boats nearby?
 
Thanks. Skeg (like the keel which is encapsulated) is fibreglass. No signs of buried wires! Don't know if there is any steel inside but it doesn't appear inside the hull above.
 
[ QUOTE ]
Does such a solitary unconnected anode do anything to protect you from other boats nearby?

[/ QUOTE ] NO. A solitary unconnected anode does absolutely nothing, for you or anyone else.

Once we start talking about other nearby boats (in marinas) we are into the realms of corrosion by stray currents being conducted by the earth connections in shore power connections left permanently plugged in. That is prevented by the use of a Galvanic isolator
 
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