Break your bonds expert says

[Boatcrazy]

Appreciate the comments. To answer your comment, no, we do not blow the GFI/CB on the marina power pole, but I have not put an amp meter on the green AC ground wire....and I will try that. I've considered a leak in the bilge (all DC), but everything in the bilge(2 bilge pumps, 2 electronic switches, and a hi=water sensor) has sealed wires, and the connections to power and switches are all 2'-3' above the bilge. But I guess a sealed wire could have a crack in the insulation, or something like that(??) Again, something worth checking. I've also read where the hi copper content in anti-fouling paint could be a conductor if the sacrificial zincs are not insulated from the bottom paint/ bottom paint sloped over the zincs?? All things worth eliminating, I guess.

 

[diver dave]

Check the makeup of the various "bronzes" and you will see little to NO zinc.
...

Sheesh. Rant, out.

not really:

Cu OFHC electrical wire 100Cu
Phosphor Bronze-hardened 90Cu/10Sn to 98Cu/2Sn
Silicon Bronze "bronze" fasteners 96Cu/4Si to 99Cu/1Si
Naval Brass 60Cu/39Zn/1Sn
Red Brass piping, thru hulls 85Cu/15Zn
Yellow Brass common "brass" fasteners 65Cu/35Zn
Manganese Bronze props, struts 58Cu/39Zn/1.5Fe/1Sn
Nibral better props 81Cu/9Al/5Ni/4Fe/1Mn

 

[rgano]

Point taken about manganeze bronze with has other elements to place some of the zinc making it cathodic to zinc. All those others are not real bronze like phosphor and silicon bronze which fastened the planks of my wooden trawler. But the real discussion is about bonding, and I am sad to see this issue of unbonding rear its ugly head here.

 

[sdowney717]

Appreciate the comments. To answer your comment, no, we do not blow the GFI/CB on the marina power pole, but I have not put an amp meter on the green AC ground wire....and I will try that. I've considered a leak in the bilge (all DC), but everything in the bilge(2 bilge pumps, 2 electronic switches, and a hi=water sensor) has sealed wires, and the connections to power and switches are all 2'-3' above the bilge. But I guess a sealed wire could have a crack in the insulation, or something like that(??) Again, something worth checking. I've also read where the hi copper content in anti-fouling paint could be a conductor if the sacrificial zincs are not insulated from the bottom paint/ bottom paint sloped over the zincs?? All things worth eliminating, I guess.

You could try measuring for DC voltage on those thru-hulls. Put positive on the bronze, and negative back to the battery. Depends though on how they are bonded and grounded. If they are well grounded wont be any significant voltage on them. If they are only bonded, not grounded maybe some volts since to make a battery, you need different metal potentials according to the galvanic scale immersed in an electrolyte, (sea water).
And also check the ohms between various under bronze parts.

My own boat, none of the thru-hulls are connected by any wires to anything, and I have never had any problems, yet.

 

[boatpoker]

I asked a noted expert about bonding and his reply was along the lines of, "As a licensed ABYC surveyor, I can not suggest or recommend removing your bonding system. But (Whisper) nothing on my boat is bonded." I promptly removed the whole bonding system from my sailboat, which I expected to keep forever. I'd remove it from our trawler but we'll have to sell it in a few years and I don't want a flap with the buyers survey.

There is no such thing as a licensed ABYC Surveyor. ABYC does not license nor certify marine surveyors, in fact no one licenses marine surveyors.

As an ABYC Certified Marine Corrosion Analyst I will say only that this is all settled and proven science no matter the opinions here.

 

[diver dave]

And, it shall remain a secret. [emoji41]

 

[sunchaser]

Seems that in 50 years of sailing/motoring, nothing has changed. Still no one knows

For vessels without an IT:
Plug into the newer 30ma GFCI dock wiring setups and you’ll know real quick as to the adequacy of your vessel’s grounding systems.

 

[diver dave]

More precisely; A GFCI tests the adequacy of the insulation between Line and Neutral off of Earth/Ground.

A more direct measurement is using an Insulation Resistance tester.

 

[sunchaser]

A more direct measurement is using an Insulation Resistance tester.

Just curious, is an IR tester commonly used and carried by a marine electrician? As an aside, so far BC is not pursuing the US 30 ma GFCI standard. Different countries, different codes.

 

[diver dave]

Just curious, is an IR tester commonly used and carried by a marine electrician? As an aside, so far BC is not pursuing the US 30 ma GFCI standard. Different countries, different codes.

I carry a Fluke 1503; but, i'm not a marine el.

In my travels, most industrial applications that worry with this stuff, either a Hi-Pot test is called for, or a IR test. The IR is a better test for the threats of a boat. It is done with a powered OFF system. Shore cable disconnected.
Line and Neutral are temporarily shorted together; lets say at the shore inlet. Then, the IR meter is attached from the L/N pair, against BOAT ground. A 500V dc signal is presented across that interface, and Ohms are read. It is a HV Ohmmeter.
Lets say you want to qualify a 120 Volt system to 5mA leakage. That equates to 24,000 minimum Ohms. Less Ohms may result is GFCI trouble.

Of course, there are some hidden caveats. The first is you must disable, temporarily, the Reverse Polarity system. This can be a simple 120V light bulb glowing if N and L are reversed. Otherwise, it would introduce an unwanted ground current, causing a bad reading.
There is another, 2nd order effect; and that is capacitive coupling from L to GND, that the DC IR tester will not measure. If you had very long feeders, this might be an issue with certain GFCI triggers, if they did not take the real part of the complex current. I don't know enough about typical GFCI's to know this answer. I don't suppose it is an issue with the scale of work talked about here with small boats.

Important note: a GFCI protected system does NOT measure the "goodness" of a grounding system. In fact, in old homes with NO ground system, GFCI's are used very successfully to reduce shock risk, same as in a modern home with grounded circuits.

 

[sdowney717]

I carry a Fluke 1503; but, i'm not a marine el.

In my travels, most industrial applications that worry with this stuff, either a Hi-Pot test is called for, or a IR test. The IR is a better test for the threats of a boat. It is done with a powered OFF system. Shore cable disconnected.
Line and Neutral are temporarily shorted together; lets say at the shore inlet. Then, the IR meter is attached from the L/N pair, against BOAT ground. A 500V dc signal is presented across that interface, and Ohms are read. It is a HV Ohmmeter.
Lets say you want to qualify a 120 Volt system to 5mA leakage. That equates to 24,000 minimum Ohms. Less Ohms may result is GFCI trouble.

Of course, there are some hidden caveats. The first is you must disable, temporarily, the Reverse Polarity system. This can be a simple 120V light bulb glowing if N and L are reversed. Otherwise, it would introduce an unwanted ground current, causing a bad reading.
There is another, 2nd order effect; and that is capacitive coupling from L to GND, that the DC IR tester will not measure. If you had very long feeders, this might be an issue with certain GFCI triggers, if they did not take the real part of the complex current. I don't know enough about typical GFCI's to know this answer. I don't suppose it is an issue with the scale of work talked about here with small boats.

Important note: a GFCI protected system does NOT measure the "goodness" of a grounding system. In fact, in old homes with NO ground system, GFCI's are used very successfully to reduce shock risk, same as in a modern home with grounded circuits.

I have little neon bulbs for my reverse polarity. Your limited to something like 25,000 ohms for neutral to ground devices, and I think mine is 40K. I got rid of my buzzer alarm due to gfci issues.
The Marine Installer's Rant: The reverse polarity light AC leaking musing

The current has to pass through the 25K resistor. Why a 25K resistor? It a ohm's law, and GFI outlet thing. Without dragging you through the math, the current is limited to only 4.8 milliamps. This is typically just under the current needed to trip the GFI outlets on your boat, and likely won't cause spontaneous combustion.

 

[Xsbank]

<sigh> For those of you who are non-believers and have bronze wheels, I invite you to remove your bonding. Then next haulout, smack one of your (pink) blades with a blunt object (a small hammer, not your wife) and get someone to photo the results. This will prove that (some) bronze, the kind generally used for wheels, contains a significant amount of zinc. It will also prove the veracity of bonding and why most boaters bother with bonding and a bunch of money buying all those anodes.

For those of you who are believers, buy a silver chloride anode, connect it to your multimeter and measure the results. That will tell you definitively whether your bonding is good enough. I believe Calder has the numbers you are interested in.

SOME wooden boats have adverse effects from bonding (zinc-plated fasteners, for example, or some stainless) but I don’t know enough about wood boat bonding to annoy you.

 

[bglad]

Haloing around thru-hulls

It is called haloing. I have not had an opportunity to study a specific instance but will offer a little speculation. If this has just appeared upon installation of your transformer you may now be overprotected by your anodes. Without the transformer you were helping your neighbors protect their boats so the cloud of protection created by your anodes was more scattered. With the transformer your zincs are more focused on your own parts causing the reaction your are seeing.

following...our f/g cruising boat was built with a bonding system installed, and we have not altered or changed it. But when we came back from Asia and the Medd, our 230v, 3-wire AC system was not compatible with the US 115v system...so we installed an Victron auto-sensing isolation transformer. And now, over the past 3 cruising seasons, we see the antifoul and bottom paint being "blown" off around several -but not all-bronze thruhulls! No metal loss, and no other issued that we've noted (yet!) but trying to understand what's going on and how to fix it. We spend about a month in a marina each season after we resplash, and I suspect that's when the "action" is happening. But I need to resolve the problem.

 

[psneeld]

Another thread where if you aren't familiar with the whole concept of bonding and underwater metal protection...best to research before thinking one way or another based on what I have read so far.



Posted bits and pieces of truth abound...but some put together to form a pretty hazy picture.


The bits and pieces that talk about actually measuring what is going on with a silver-silver chloride reference electrode are posts that I believe are headed in the correct direction.


A tough topic that usually isn't cleared up in short bursts found in forum threads.

 

[bglad]

Right on. I was performing an inspection on a Californian. All the underwater fittings I checked using the reference cell were the same voltage except for one bronze strut. It checked -.250 versus -.550 of the other fittings. It had no bonding connection so it was sitting at the potential for bronze versus the other parts that were. Anodes shifted the bonded parts voltage more negative.

Another thread where if you aren't familiar with the whole concept of bonding and underwater metal protection...best to research before thinking one way or another based on what I have read so far.



Posted bits and pieces of truth abound...but some put together to form a pretty hazy picture.


The bits and pieces that talk about actually measuring what is going on with a silver-silver chloride reference electrode are posts that I believe are headed in the correct direction.


A tough topic that usually isn't cleared up in short bursts found in forum threads.

 

[psneeld]

My real point is that there are definitely 2 theories of bonding....both and neither are absolute on protection....both methods can be used and mixed on the same boat and have been successfully used for many decades.


Without understanding and testing...mixing and matching (kinda like the compilation of posts) is never good...so manufacturers and "expert's suggested methods" usually simplify. So what happens is a lot of people may understand well enough to post...but if it's only a "part" of the story (typical 1-3 paragraph length post) it sounds erroneous to others ....and taken in a vacuum....it would be.


Do either concept partially and fail to check with a silver-silver chloride reference electrode and bad things happen. If you aren't going to check...the next best thing IS total bonding and using the table that suggests how many square inches (or pounds - I forget) of zinc to use for how much underwater metal you have.

 

[sdowney717]

I only unbonded my bronze through hulls, the struts and rudders are still bonded. And I suppose prop shaft connects by way of its bolted connection to them. The fuel tanks are also bonded to them.

Its been 20 years like that, and last haul out in 2014, I took out the thru hulls and they were all good.

 

[diver dave]

...

Its been 20 years like that, and last haul out in 2014, I took out the thru hulls and they were all good.

Lucky guy to be on a 5 year haulout schedule.

 

[sdowney717]

Lucky guy to be on a 5 year haulout schedule.

I know its due. In the summer I do get in the water and scrape it. We have a shallow sandbar here on Chisman creek. I can stand in the water and get most of it with a long hoe I straitened. The water is brackish. Yorktown VA is at upper left corner.