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Corrosion Control Gone Wild

2K views 9 replies 4 participants last post by  Broacher 
#1 · (Edited)
Hi,
My boat has a Bartell (Newport, Cal. U.S.A.) Corrosion Control System. On recent haul out shocked to see all the bottom paint gone from around all the thru-hulls. A new propellor looked as if it had been subjected to a tin plating process. Zinc anodes hardly affected.

Hull sports a large zinc anode and a thru-hull reference anode both wired to the Bartell box. The reference anode – just a wire loop really, had been painted over. All thru-hulls, engine and prop shaft are also wired to this box.

Bartell box has a milliameter and a volt meter.

Have no manuals or information about this system. Wondering how to check/calibrate this system or to just disconnect it.

Can anyone advise?

Thanks
 
#2 ·
I'm assuming this is an impressed current system. Google that and you will get general information.

It is odd that there are zincs included; generally these systems operate using only inert anodes, but perhaps either the installer or the PO thought a back up was a good idea. That explains the rudder, which is unharmed.

However, when they added zincs to a system that was designed without them (sounds like the case), then the total voltage will be too great, explaining the paint damage.

Personally, I think using zincs is a more robust, dependable approach for smaller boats. Certainly having both is problematic. Since the last "expert" screwed you up, I suggest reading up on the topic.
 
#4 · (Edited)
What is an "inert" anode. An anode in a cathodic cell is an anode !
What would be the purpose in fitting a lump of inert metal if there even was such a thing. As all metals have a natural voltage potential, how could any metal be electrically inert ?

Sorry for the multiple questions but your statement confuses me.

PS. Every impressed current system I've seen did have anodes.
 
#3 ·
Thanks for the helpful observations and search suggestions pdqaltair. Lots to read, and a few possible local contacts to consult.
One thing I learned is that there is a desirable electrolyte potential to be maintained. Wish I had known mine prior to my haul-out with the painted over reference anode. Next thing is to see if my system is actually working. I read a reference voltage but no current (milliamps) being delivered. Currently reads about 0.18v.
Next seems to be to either go with this system if correctly calibrated, hauling again to remove the zincs that I just put on the prop shaft, or just disconnect it.

I like the idea of just zincs but someone went to a lot of trouble installing it so it is definitely worth a little more more investigation. Still hoping to track down Bartell Inc.

I am also wondering if my or someone else's shore power plug-in had something to do with this. Will let you know.

Meanwhile have attached before and one-year-later prop pics, the paint damage and the reference zinc and anode.
 

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#9 ·
Sounds like reference anode painted over is the source of your problem with the impressed current system. obviously it cant perform as a reference if it is painted over. System will wind itself up to full power due to no feedback from the reference, all the paint damage next to metallic components is due to these being "overprotected" by the system at full output.

the back up zincs will not have been used as the components they are attached to are already overprotected.

clean off the reference electrode and all may be well again.

you should have plain zincs installed as well as impressed current, standard practice to provide this protection in case the impressed system fails or has no power.
 
#10 · (Edited)
Cracked open the Bartell Anti-Corrosion System box. It is toast and has been removed. Interesting, it used to be powered by a single AA battery, no 12volt or 120volt connections. Three connections, one to the reference anode, one to that big zinc on the hull, and one to all my thru-hulls and propshaft, thence to the engine block.

Tested the system using a meter as suggested. Grossly over protected at nearly 1000 millivolts. No stray current isues.

Tested again after disconnecting all three wires from that box, leaving all thru-hulls connected to the engine. Clipping on to the shaft or a thru-hull, I still get a concerning 950millivollts. Lifted bonding brush from the shaft, same reading.

Is that big hull zinc still in play? I also have zincs on the skeg and propshaft, too many? Wondering what to try next.
 

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