Current in bonding wire

[sailorboy1]

Everyone is wrong!

We should just crawl into a hole now as there is only one who can save us, but he wouldn’t

That’s just so, ................... well something

[Paul Elliott]

Originally Posted by boatpoker

No. It is just not worth the arguments and ridicule from the dock experts. I've learned my lesson.

Obviously it's up to you, but I am honestly interested in learning about this. Maybe you could speak your piece and then never click on this thread again? Or PM me, but I think others would be interested too. I promise I won't follow you around and argue.

[skipmac]

Originally Posted by Paul Elliott

Obviously it's up to you, but I am honestly interested in learning about this. Maybe you could speak your piece and then never click on this thread again? Or PM me, but I think others would be interested too. I promise I won't follow you around and argue.

Me too. Please.....


I also promise to severely chastise all those that argue or denigrate the information.

[boatpoker]

Originally Posted by sailorboy1

Everyone is wrong!

We should just crawl into a hole now as there is only one who can save us, but he wouldn’t

That’s just so, ................... well something

OP .... See what I mean.
Call the ABYC guy like I said.

[sailorboy1]

Originally Posted by boatpoker

OP .... See what I mean.
Call the ABYC guy like I said.

Talk about a copout!

[Paul Elliott]

Originally Posted by sailorboy1

[.......]

Sailorboy, please stop. I would like to hear what boatpoker has to say.

[Dymaxion]

BoatPoker.... simple question, recommended reading/reference on this topic? One or two titles would help. Tx

[patja]

I fully intend to get an ABYC electrician out once I've finished my DIY corrosion survey. At a minimum I value getting independent confirmation of my measurements and conclusions.

I value the expertise and opinions expressed here and can sort through the wheat from the chaff. I give more credence to what I can read in a book or see published by someone with experience and training, but education and learning can be found from other boaters as well. I give more weight when I hear the same thing from multiple sources and it matches my measurements and experiences.

Paul provided a couple great resources at the top which I hadn't seen before and spent some time studying (the ProMariner pdf and the yachtwork . com link). They both warn about overprotection and paint damage, which seems consistent with what I'm seeing. My paint is also very high copper content which I suspect is relevant...it was Seahawk Tropikote Biocide (75%) and I just had Sharkskin (45%) put on.

Those resources also emphasized the "watch the voltage on the silver/silver chloride anode while turning everything on and off" approach to identifying if and where there is a current leak. I'm going to take another exhaustive crack at that tomorrow, and bring my second-best multimeter along to compare to the Fluke.

[chris95040]

Originally Posted by boatpoker

No. It is just not worth the arguments and ridicule from the dock experts. I've learned my lesson.

I think you made the right choice [emoji23]

[Bermuda Forte]

Watching this one

[Paul Elliott]

Originally Posted by chris95040

I think you made the right choice [emoji23]

And I think he made the wrong choice.

Look, I'm an electronics engineer, and there are some areas where I'm a bit of an expert (and some where I'm a lot of an expert, but generally those areas have little to do with boats). When I know something about a topic I will try to share that knowledge at a level appropriate to the community. I like to think some people find this useful.

Sometimes people argue with me on topics where I am quite competent. Usually they're wrong, but once in a while they're right and I get to learn something. I appreciate that.

Galvanic protection isn't exactly nuclear physics, but I'm sure there are important details of which I am unaware. Perhaps some of these details are critical. I hope boatpoker reconsiders his position.

[chris95040]

Originally Posted by Paul Elliott

And I think he made the wrong choice.



Look, I'm an electronics engineer, and there are some areas where I'm a bit of an expert (and some where I'm a lot of an expert, but generally those areas have little to do with boats). When I know something about a topic I will try to share that knowledge at a level appropriate to the community. I like to think some people find this useful.



Sometimes people argue with me on topics where I am quite competent. Usually they're wrong, but once in a while they're right and I get to learn something. I appreciate that.



Galvanic protection isn't exactly nuclear physics, but I'm sure there are important details of which I am unaware. Perhaps some of these details are critical. I hope boatpoker reconsiders his position.

Oh I couldn't agree more about learning and listening. I'm an electrical engineer and still suffer through conversations about 'overprotection', whatever that is. .

Usually it goes like this one did, where I boil the topic down to a simple example and I hear crickets in response, but often enough I get to learn something.

But folks who post something like 'you are all wrong! but im not tellin ya why!!!!' ??? Not the least bit interested in their opinion. Maybe after they dry out a bit.

[GordMay]

From ➥ http://marineprotectionsystems.com.a...-Explained.pdf

Common issues with over protection include:

Paint Blasting – the hydrogen blistering of paint occurs because of the destruction of the adhesion between the coating and the base to which it was applied (or substrate). This can be often seen near where zinc anodes are attached to fibreglass hulls. The process of blistering is referred to as “cathodic disbondment”.

Repels Anti-Fouling and Propeller Coatings – in the same manner as paint blasting, over protection can lead to the non-retention of anti-fouling and propeller coatings due to incompatibility of the application with sacrificial anodes. This can render the application ineffective and the increased
barnacle and other marine growths lead to vessel inefficiencies and costly manual maintenance.

Lure of Marine Growths – excessive cathodic protection a
ccelerates the formation of calcareous deposits including the calcium carbonate coral-like structure commonly encountered on a vessel’s hull, rudders and propellers.

Wood Rot – cellulose is a natural polymer which gives wood its remarkable strength. Cellulose is a major component of wood where lignin holds the cellulose together. Over protection resulting from the galvanic current flowing between the anode and cathode destroys the lignin and thus the effects of wood rot are often noted.

Alkali Attack – resulting from excessive cathodic protection systems, damaging wooden or metallic hulls. Over protection can lead to the formation of alkaline conditions on metallic hulls when there is insufficient flow of water to return the water to its natural pH, resulting in accelerated corrosion. This can be accentuated as the paint blisters to create an even more alkaline condition and further lead to rapid deterioration of the submerged metal.

[chris95040]

Originally Posted by GordMay

From ➥ http://marineprotectionsystems.com.a...-Explained.pdf

Common issues with over protection include:

Paint Blasting – the hydrogen blistering of paint occurs because of the destruction of the adhesion between the coating and the base to which it was applied (or substrate). This can be often seen near where zinc anodes are attached to fibreglass hulls. The process of blistering is referred to as “cathodic disbondment”.

Repels Anti-Fouling and Propeller Coatings – in the same manner as paint blasting, over protection can lead to the non-retention of anti-fouling and propeller coatings due to incompatibility of the application with sacrificial anodes. This can render the application ineffective and the increased
barnacle and other marine growths lead to vessel inefficiencies and costly manual maintenance.

Lure of Marine Growths – excessive cathodic protection a
ccelerates the formation of calcareous deposits including the calcium carbonate coral-like structure commonly encountered on a vessel’s hull, rudders and propellers.

Wood Rot – cellulose is a natural polymer which gives wood its remarkable strength. Cellulose is a major component of wood where lignin holds the cellulose together. Over protection resulting from the galvanic current flowing between the anode and cathode destroys the lignin and thus the effects of wood rot are often noted.

Alkali Attack – resulting from excessive cathodic protection systems, damaging wooden or metallic hulls. Over protection can lead to the formation of alkaline conditions on metallic hulls when there is insufficient flow of water to return the water to its natural pH, resulting in accelerated corrosion. This can be accentuated as the paint blisters to create an even more alkaline condition and further lead to rapid deterioration of the submerged metal.

Thanks, Gordy, great post. I've always heard about overprotection problems with wooden hulls, and admit I don't really have enough understanding of that to offer an opinion.

Returning to the basic example I gave, a through hull, a zinc, and a bonding wire, I still don't see what ill effect there would be with "too much zinc". I should clarify I'm assuming a plastic hull.

Maybe nearby anti-fouling paint is going to be affected, or i'll get some more marine growth. OK, let's talk about that. So what, you want protection current, but not so much that it effects the paint or lures critters?

Engineering the "right sized" zinc would be impossibly complex. First off, the zinc itself is changing as it corrodes, the surface area in contact with the water is changing, the electrolyte content in the water you are floating in is dramatically changing from one location to the next, the parts you are protecting, and their connection to the water, are also changing: surface characteristics change, petinas form, barnacles grow, paint is applied, paint wears off. By the way, what is the resistance of your bonding wire? All of these things are going to have a dramatic impact on your actual voltage between your "right sized" anode and your cathode.

For this reason I'd guess most protection systems are designed around a much simpler premise: Current in the right direction good, current in the wrong direction bad. You put a big ole anode in there to keep the current flowing in the right direction so your metal goodies don't disappear on you. And if there is some ill effect that the protection current has on bottom paints, etc, you can rest assured in the fact that no matter how much anode you put down, you are never going to *exceed* the voltage that's determined by simply looking at the galvanic series and comparing the anode and cathode.

If I were to engineer a system that was attempting to limit the "good" current to alleviate it's impact on my bottom paint, I'd do it through choice of the anode material, or at the bonding mechanism, I wouldn't try to "size my anode" - that sure sounds like a fools errand since the electrolyte solution, the anode geometry, and the surface conductivity of the metal you are protecting are all changing.

[patja]

Thanks Gord. More data supporting the hypothesis that what I am seeing is consistent with what one would expect in an overprotection situation.

I pulled my zinc fish anode out of the water, which still puts me at .960 volts on the silver/silver- chloride anode connected to the bonding, which seems to still be in the overprotection range. Granted the zincs are all brand spanking new as the boat is fresh from the yard with new zincs so the protection level will only go down. But I don't want it blasting my paint off again. The extra prep on my bottom paint job was almost $1k. On the plus side, the metals were protected -- no pitting or sign of any loss of metal.

I am considering having a diver out to swap my large bonding zinc that is on the hull for a smaller one to drop my protection level hopefully down into the .800 range. The current zinc is a Martyr MZ404

In the pdf from ProMariner which Paul linked, they recommend their own product (go figure) called the Deluxe Corrosion Controller. I am having trouble finding much in the way of documentation on it, but it looks like it comes with its own silver/silver chloride anode which is to be mounted in a thru hull for constant monitoring, and then it has a potentiometer to dial up or down your protection level (voltage). On its own it is not too expensive, but I guess I would have to swap out a transducer for its anode, and even then that might not work...the thru hull fitting pictured on the product looks to be smaller than the ones used by my transducers, so it might need yet another hole in the boat to accommodate it, which I am loathe to do (I just spent a month on the hard in the yard!). Does anyone have experience with this thing and know how it adjusts the protection level?