anodes necessary?

[huggy]

i've read a great deal on this subject and am totally confused.....my 30 year old broom skipper has been on the norfolk broads all her life and there are no anodes that can be seen. Are they necessary in fresh-water? She's grp with shaft driven bronze prop and steel rudder. Is this all gonna dissolve in the near future?

 

[BrendanS]

They've probably all dissolved away by now /forums/images/graemlins/smile.gif

Yes, generally speaking they are required in all waters. If you don't think you have any problems, then by all means carry on, but it would probably be wise to protect the expensive metal underwater bits of your boat with anodes, just in case you visit somewhere that anodic problems are more prevalent than where you are moored.

 

[boatmike]

Less of a problem in fresh water than salt water. If she has lasted this long without problems and everything is sound I would not get overly concerned, but if there is room a shaft anode would no no harm and is cheap and easy to fit.

 

[Jim_H]

I thought I could get away without them until we hauled out and found large lumps of the keel missing (steel hull).

The amount of metal that had disappeared in 10 months was staggering.

Blossom now has so much zinc underneath her that I fear for any oilrig that we pass !

 

[huggy]

thank you all. OK then, this shaft anode thing,, cheap and easy?..how do i go about this? where is it fitted, what should it be made of and why exactly do you think it ought to be done.

many thanks... ( Im not really a dumbhead ...just wish i'd paid attention in physics)

 

[charles_reed]

There are two schools of thought on the subject

and if you get two experts you'll get at least 3 opinions.

One school reckons if you have no anode and no metallic bits to far apart on the electrogalvanic scale you'll have no problem.

The other is obsessionally neurotic and demands that every piece of below the waterline metal is connected to a large surface area circuit and thence to an anode. All unconnected pieces should have thier own sacrificial anodes.

It is my experience that the first school is sometimes wrong and the second is infrequently wrong.

If you're in fresh water the problem is somewhat mitigated and if you have shorepower and other boats around you it is exaggerated.

My daughter had a colleague who was, allegedly, the UK's foremost authority on galvanic corrosion. She found his theories confusing, I found discussion with him opaque and he finally had a nervous breakdown and was hurried into early retirement.

 

[rcackett]

Hi huggy, I too have a 30 yr old Broom 30 MKII on the Thames. Lifted her out this winter having only just got the boat and found that I have two anodes bolted together through the rudder. They were pretty shot, replaced with a new pair of magnesium ones from here, Z-Guard web page cheap too. I don't have an anode on the shaft but as I can't see any erosion anywhere else I'm not going to bother fitting one too many other bits to buy first! /forums/images/graemlins/smile.gif

 

[huggy]

Yep....just as i said...still no firm conclusion then. thanks to you all however.....i'm gonna forget all this and carry on enjoying the boating......yes, its great in this weather..nobody else about! /forums/images/graemlins/grin.gif