Anode corrosion

[Greg & Jax]

Hi all .

My boat is out to have the Hull painted and the corrosion on the anode,s  look odd , these have been on about 8 years I do have more on and they look normal .

Just wondered if anyone can shed some light on it . 

Regards Greg. 

[Alan de Enfield]

To me that looks like an anode that is working (doing its job).

Do the other anodes look as if they are still new or just partly 'worn' ?

 

For comparison :

 

 

[Greg & Jax]

Hi Alan, 

The left hand anode is about 8 years the right one about 3 years old .

[Alan de Enfield]

 

 

I'd suggest that in another 4 or 5 years the 'new' one will look like the 'old' one.

 

Anodes can develop a 'crust' (white 'rust') which stops them working and they do need cleaning on a semi-regular basis. A wire brush is enough to remove the 'rust'

 

Recommendations are that an anode should be replaced when it has reduced by about 1/3rd - 1/2 as the weight reduction will no longer give you sufficient coverage.

 

It is possible to 'over anode' a boat  and ideally the old anodes should be removed when new ones are attached. 'Over anoding' a steel or aluminium boat can have serious detrimental effetc on the hull.

 

Having an excessive number of sacrificial anodes installed on your boat can lead to unintended consequences. Boats with fiberglass hulls are less likely to be affected by over anoding, but wooden and metal hull boats are particularly susceptible to the negative effects of over anoding which include:

• Burnback and discoloration
• Paint delamination and flaking
• Caustic wood rot

(Source : PBO)

Edited February 5, 2023 by Alan de Enfield

[Greg & Jax]

Thanks Alan. 

I will leave them as they are and see how they look next time round .👍

[Tony Brooks]

1 hour ago, Alan de Enfield said:

It is possible to 'over anode' a boat  and ideally the old anodes should be removed when new ones are attached. 'Over anoding' a steel or aluminium boat can have serious detrimental effetc on the hull.

 

Funny you should say that. When I saw the flaking paint, that was my immediate thought.

[tosher]

Worried now.    Last year when out for blacking the 4 hull anodes were about 50% worn and not wanting to throw them away but worried they might disappear before my next lift out I left them in place but fitted 4 additional ones as well. After lifting back in the water I noticed the indecator needle on my galvanic isolator had moved from it's  usual pass zone position to half way between the pass and fail zone. I have measured the voltage between the incoming shore power earth lead and the boat earth and got 0.511 volts. Could this be due to too many anodes?  Thanks.

[ditchcrawler]

44 minutes ago, tosher said:

Worried now.    Last year when out for blacking the 4 hull anodes were about 50% worn and not wanting to throw them away but worried they might disappear before my next lift out I left them in place but fitted 4 additional ones as well. After lifting back in the water I noticed the indecator needle on my galvanic isolator had moved from it's  usual pass zone position to half way between the pass and fail zone. I have measured the voltage between the incoming shore power earth lead and the boat earth and got 0.511 volts. Could this be due to too many anodes?  Thanks.

No thats due to an electrical problem

[beerbeerbeerbeerbeer]

Any anode I’ve had rots away,

seems a waste of money 

 

 

[Tracy D'arth]

18 hours ago, tosher said:

Worried now.    Last year when out for blacking the 4 hull anodes were about 50% worn and not wanting to throw them away but worried they might disappear before my next lift out I left them in place but fitted 4 additional ones as well. After lifting back in the water I noticed the indecator needle on my galvanic isolator had moved from it's  usual pass zone position to half way between the pass and fail zone. I have measured the voltage between the incoming shore power earth lead and the boat earth and got 0.511 volts. Could this be due to too many anodes?  Thanks.

You have an electric current eating your boat. Move it and see what happens, could be another boat near you or the piling.  You could have a problem on your electrics, leakage to hull, possibly a wet connection?  Sort it out before you sink.