Can you have too many many anodes?

[ChasB]

I'm trying to avoid taking my boat out of the water this winter - there's very little visible fouling, and the boat's hardly moved, so the anti-fouling will be ok for another year. But what about the anodes?

I've already suspended a hanging anode to supplement the two down there, and am about to fit a galvanic isolator.

But it occurs to me that I could hang another two off each side astern - in effect surrounding the props. They're only £16 ea - a lot cheaper than a hoist out.

Is there a prob with this?

/forums/images/graemlins/grin.gif

 

[William_H]

No no problem at all with extra anodes. If the hanging anodes are found to be dissipating rapidly however that might indicate the attached anodes are also dissipating rapidly.

What is far better than galvanic isolator is no connection to the mains power at all. But if you must have mains power on 24/7 then if there is no connection of the mains and appliances to the boat electrics you won't need a GI. However if you want the mains earthed to the ships earth for human safety then use a GI.
Perhaps you understand all this but I suspect a lot of people don't. A GI will no of itself so any good, only if you have a connection mains earth to ships earth and can open that connection and fit the GI in.
olewill

 

[ccscott49]

Yopu can have too many anodes for a wooden boat, but not a GRP one.

 

[Bajansailor]

Apologies for asking something so fundamental, but are your hanging anode(s) mounted on wire cables which are then connected internally and electrically to (eg) the engines, sterngear etc to be protected?

If they are not, they should be, as otherwise they are not going to do anything.

 

[ChasB]

Yes, and using stainless steel wire.

 

[Grajan]

On steel boats you can overprotect, speak with MG Duff who can give you chapter and verse on what you are trying to achieve

 

[VicS]

It may be worthwhile taking a peek at MGDuff's website

 

[ChasB]

Thanks that is very useful. [ QUOTE ]
One anode will be required to protect each shaft assembly. Bronze or stainless steel rudders or GRP rudders with bronze or stainless steel stocks should also be bonded to the same anode, however mild steel rudders will require separate anodes.

[/ QUOTE ] I think that applies to me. /forums/images/graemlins/confused.gif Separate anodes for the rudders?

This is very pertinent to me: [ QUOTE ]
Not all anodes are suitable for every environment, for example the surface of a zinc or aluminium anode will if left in fresh water for some time become covered with an off white crust of oxide which effectively seals the anode and stops it working even when returned to salt water. Zinc Anodes suffer a similar problem even in brackish conditions whereas Aluminium will continue to operate effectively in river estuaries and other areas of brackish water indefinitely. The consequences of this passivation of the anode are that the next most anodic item within the anode bonding system will start to sacrifice itself which could of course be very serious.

It is therefore very important to check Zinc and Aluminium anodes after any trips into fresh water and if necessary clean off or change the anodes.

Should a vessel move into fresh water for more than two weeks MGDUFF recommend that an alternative anode system is used suitable for fresh water situations. Magnesium Anodes on the other hand have a much higher driving voltage than zinc or aluminium making them highly suitable for use in Fresh Water, they will however become very active in salt water where they will probably only last a matter of months. Protected surfaces can build up a layer of off white calcareous deposit which will be difficult to remove.

Magnesium anodes are not designed for prolonged use in sea water and if you are taking your boat into a salt water location for more than seven days (Fourteen days in any one year) you should consider changing the anodes. Magnesium Anodes should never be fitted to wooden hulled vessels as they can damage the timber.

[/ QUOTE ] Oh dear, that's worrying. Lindon Lewis boatyard in Shepperton fitted zinc anodes a couple of years ago, so I've used a hanging anode of the same type. So the anodes may well still be there intact ( covered with an off white crust of oxide) but the props might be deteriorating? /forums/images/graemlins/frown.gif

oh bummer.

 

[Mrnotming]

see thread "batteries totally flat in three weeks"