zinc anodes & antifouling

[Guest]

I have a problem that I would like to understand, and perhaps there is someone with a technical understanding of the issues involved.

I use International Micron CS antifouling, a 'soft' copper based antifouling.

I have noticed that skin fittings that are connected to the zinc anode are badly fouled after a year in the water, whereas skin fitting NOT CONNECTED to the zinc anode are NOT fouled in any way.

Why?

I always understood that skin fittings should be connected inside the boat to the zinc anode as protection against electrolysis. It was accidental in my case that some were not connected, but in being so, this strange anomaly was discovered.

 

[ccscott49]

Never heard of that before, but I'm sure somebody has! Why don't you disconnect the skin fittings, they dont need protection, if they are bronze!!!! If not then they maybe need it!

 

[Trevor_swfyc]

This is interesting, skin fittings as said, if bronze do not need to be connected to the anode (Zn). Skin fittings do attract barnicles due to turbulence caused by tidal flow over them.
Connection to a Zn anode could affect the Copper Oxide in the antifoul by inhibiting the release of Cu Ions, as the Zn is far more electro negative than Cu. Thats my best guess.
In any case I would not connect my skin fittings to the anode.
The manufacturer does recommend that this antifoul is not applied to zinc or aluminium perhaps for the reason stated?

Trevor

 

[Guest]

Grecian 2000 and the Bronze Age

Grecian 2000, now that's something that really does work !

I do not have a phd in chemistry or an 'ology' in metals, but I now seriously believe that anodes, and the need to have anodes, is largely a means of someone else getting money for not a very good reason.

My boat is 29 years old , does not have any anodes or attachments. I took all bronze Blakes type seacocks (originals I believe) and there is no wastage at all. Ditto other Bronze fitting like rudder heel etc. I only have room for a shaft collar anode that probably falls off pretty quick ( I have never seen one again after putting one on).

Ions and and the like are floating about in seawater and everywhere else. That's what eats up anodes.

I do admit however (Steel and ally apart boats apart) that current so called Bronze fittings and props are of joke quality because they are beaten down to a price. We really have 'the worst of brass' fittings most of the time dangling below. Anode makers and bronze makers are probably in the racket together. When are the mags like PBO going to do their own survey ( for our benefit) over say a year to prove or disprove this type of thing ?
IT's over to you..............

 

[ccscott49]

Re: Grecian 2000 and the Bronze Age

Simple, if you have all bronze fittings, IE. No zinc! and all bronze shafts and props, bronze or copper fastened wooden boat, you do not need anodes, as there is nothing to corrode. I have anodes and they are bonded to my engines etc, but they have lasted 7 years now with very little wastage, the only wastage, I think is protecting other boats or the marina. When I spend a season away form marinas, the anodes look the same as they did the previous year and I wirebrush them each antifouling, about every two years.

 

[PeterGibbs]

Re: Anodes linked to skin fittings

Why not go with the finding inferred in your quesiton and disconnect the anode from all skin fittings. I have never heard a convincing case for linking them in the chain.

This is not to conclude that an anode connected to the engine and stern gear is not other than entirely sensisble!

PWG

 

[Guest]

Re: Anodes linked to skin fittings

I think yourself Peter, and Colin , are both right and possibly myself too. We base our findings on our own experiences.

However, we hear many different views from many different directions and there is much controversy on the subject . Whenever there is controversy surely this means that the subject is not fully understood ?

What we need is data from a reasonably independent standpoint. I enjoy the IPC Mags and support them but they are falling behind in producing facts for us 'punters' in many areas.

They could get hold of three old boats - say plastic, wood and steel do various things with and without anodes and give us the facts. It would not be the total answer but it would be something. A good place would be the Solent as it has the highest concentration of boats... in Europe ?

 

[ccscott49]

Re: Anodes linked to skin fittings

The galvanic scale will tell you all you need to know reference anodes and corrosion (electrolytic) The anodes are there to protect the disimilar metals used in boats, they corrode, so your expensive bits don't its as simple as that. What should be bonded to the anodes is a different kettle of fish, which depends on what the fittings are made out of, I would bond anything with zinc in it to the anode, aswell as steel or stainless steel or galvanised steel. If a boat is wood and galvanised fastened, it needs anodes, but you can't bond every nail to the anodes, you just have to hope the nails stay dry! Its a complex subject in all, but we don't need to know the ins and outs of it all to know what to do!

 

[PaulJ]

Without going into the pros and cons of connecting skin fittings to anodes, I have a vague recollection of hearing an item on the radio many years ago about crops growing in close proximity to high voltage power lines (ie directly underneath them)having an enhanced rate of growth. Perhaps the weak electric field has an effect on the growth of the vegetation.....? Can you say whether the anodes were showing much sign of erosion which would be an indication of current flowing?