Earth bonding wires ??

[Wayfarer111]

In the process of checking chainplates last week i noticed that earthing wires (maybe 6-8 AWG size) had either corroded completely off their terminals or were in such a bad state that i cleaned them up and replaced the terminals. Most of these grounding wires i have notice have been disconnected from various positions around the boat....motor, stop-cocks, and probably plenty of other places i am yet to find. Also where they all combine onto copper strapping to the through hull zinc, that has been disconnected also.

Anyone have ideas as to why this might have been done by PO? Are these wires for lightning protection of to prevent electrolysis.....??

I'm a bit concerned about this as i'm parked near a large steel trawler in a pen with mainly fishing boats on the jetty. My knowledge of such things is limited, although these forums seem to cover just about everything boating and more.... it certainly keeps the brain ticking over

Any help much appreciated,
Scott

[Uncle Bob]

Originally Posted by Wayfarer111

In the process of checking chainplates last week i noticed that earthing wires (maybe 6-8 AWG size) had either corroded completely off their terminals or were in such a bad state that i cleaned them up and replaced the terminals. Most of these grounding wires i have notice have been disconnected from various positions around the boat....motor, stop-cocks, and probably plenty of other places i am yet to find. Also where they all combine onto copper strapping to the through hull zinc, that has been disconnected also.

Anyone have ideas as to why this might have been done by PO? Are these wires for lightning protection of to prevent electrolysis.....??

I'm a bit concerned about this as i'm parked near a large steel trawler in a pen with mainly fishing boats on the jetty. My knowledge of such things is limited, although these forums seem to cover just about everything boating and more.... it certainly keeps the brain ticking over

Any help much appreciated,
Scott

Hi on the other coast, my boat has no earthing or grounding wires at all, mid 90's boat and none of those that I have mentioned this topic to have either. Seems to me that it is largely an American thing, though probably found elsewhere.

[Pete7]

Same here in the UK, no valves connected. However, the rudder shaft and p bracket are connected to the main anode. Propshaft has its own anode.

Pete

[GordMay]

If the photo is showing a chainplate, then the disconnected wires are lightning mitigation ground. A lightning gnd used to be specified as #6AWG, now recommended #4AWG wire.

[HankOnthewater]

Hi Scott, I guess you are in Bandy Creek with the fishing boats? You didn't say expressively, but your boat is fibreglass? Yes, I have seen and been on a steel Passport! (or maybe a copy of that?)

I have a fibreglass boat, all my skinfittings/seacocks and anything metal are connected with similar green/yellow wires, and in some paces with copper straps. However such wires, mine and yours as in the photo, are not much good with lighting strike, far too small, in my opinion. Therefore the purpose of theses wires may be to form a common ground with the external metal fittings and anode(s).
Anyway that is my take on it.

[hernandobeach]

The "earth bonding" wires are exactly that and more importantly they provide protection from electrolysis to all metal parts that may be in contact with the water. They are designed to be connected to what are termed sacrificial anodes. Sacrificial anodes are defined as easily corroded materials deliberately installed on boats (and in other applications as well) to be sacrificed to corrosion, leaving the rest of the system relatively corrosion free. A sacrificial anode is also known as a galvanic anode.

The wires you refer to bond the metallic elements of the boat to those one or more anodes. As a note the wires should be "tinned copper" to prevent corrosion. The connections should be soldered not crimp connections.

If you are concerned with lightning protection, that is a totally different subject. However the wiring system for the anodes would become part of the path of lightning should your boat be struck.

If you need to understand lightning protection, just ask and I will explain what works and what does not. But I would need to know more about your boat to answer it properly.

I hope this helps

John

[sailcrazy]

Following, trying to better understand a bonding system.

[Seighlor]

Originally Posted by sailcrazy

Following, trying to better understand a bonding system.

Ditto.

[hernandobeach]

Did my answer confuse you? Want a more detailed outline of how the sacrificial anodes are connected and what they do for the metal parts in contact with the water? Just ask.
John

[hernandobeach]

The reason for a "bonding" system is to bring any conductive (metal) component of a boat to what is called equal potential. Most boats have a power system of some type. That system has what is called "potential". The potential is a charge, 12V, 24V, etc. If something that is charged comes into contact with something at a different charge (body of water at "0" potential) the higher potential will seek a path to equalize the potential difference.

Imagine trying to stack water! Unless it is frozen, that will not happen unless there is something to contain it. Water seeks to be at equal potential, that is why lakes and oceans are "flat" except for wave and current action.

Any charged metallic object will be exposed to corrosion and loss of mass. That is why you see "sacrificial anodes" on shafts, rudders, keels, trim tabs, outboard motors, etc. The idea is the anode will be subject to "galvanic" action, loose mass and prevent the other metal parts from being corroded and loose mass.

This help?

John

[Ahmet Erkan]

Originally Posted by Uncle Bob

Hi on the other coast, my boat has no earthing or grounding wires at all, mid 90's boat and none of those that I have mentioned this topic to have either. Seems to me that it is largely an American thing, though probably found elsewhere.

Hello Uncle Bob,
I hear you and concur about the phrase "American thing".
Drive a big truck, bigger the better and it don't matter if the back of the truck is empty 99% of the time or the truck is too big to fit in your garage or takes 1.5 parking spots.
Use bigger wire on your boat or house wiring, bigger the better and it does not matter if the wires run less than 1 degree C above the ambient air temperature or drop less than 1% voltage.
Coffee must be so hot that it burns your lips.
Beer must be so cold that your throat freezes etc etc.
Having said all that, we still like it over here :-)
Back to the originator's subject. What do the earth bonding wires do that justifies their existence?
It is my belief that they serve two purposes.
1. Safety. While connected to shore power, if a live wire comes in contact with say your engine, the bonding wire that connects your engine block to the shore power earth ground will cause the shore power circuit breaker to trip open, protecting the nearby swimmers or divers. To achieve a definite tripping of the circuit breaker (CB), the bonding wire should be big enough not to blow open like a fuse instead of the CB tripping. I know this sounds non-engineer like talking but my gut tells me 14AWG wire is more than enough for bonding a through hull or rudder shaft. Anything smaller than 14AWG wire will corrode away itself or break in the bilges anyway.
2. Corrosion prevention. In order to protect the underwater metals of a boat, a piece of Zinc (ie: sacrificial anode) is immersed in water and connected to the said underwater metal. The physics here is not so much against you that your un-bonded through hull fittings corrode away if you do not bond them. Obviously if somebody presented accurate data that un-bonded through hull fittings corrode away, twice as fast compared to bonded ones boaters in Australia would be interested to know. I do not know of such data.
My recommendation to the post originator (PO?) is to measure the DC voltage (mV) when the bonding wire is open then measure the DC current (mA) when the bonding wire is connected and make a decision based on data.
I will be glad to explain further details if there is interest.
Cheers
Ahmet

[boat driver]

bonding metal below the waterline is primarily for galvanic corrosion. lightening is another subject.
The short story of the bonding belief- If the bonding connections are maintained, then the bonded metal parts of the vessel will terminate with a thru hull zinc. This works to protect the vessel.
Where the debate becomes lively is age of the vessel and thereby maintaining this bonded system of connections. When the zinc is not replaced/or more often the connections develop corrosion, the bonded metals, missing the zinc sacrificial anode, will then set up (dissimilar metals) themselves as a battery and sacrifice the next less noble metal.
result is obviously not desired.
So if all the bonded metals are disconnected- then obviously at some point the decision was made that it was not working in a positive manner- leave it unbonded.

[Wotname]

I believe it is better to take a more historical approach as to why bonding was first used.

Back in the day of wooden hulls, the purpose of bonding metallic underwater fittings to protect the wood immediately around each fitting. The galvanic cell comprised of slightly dissimilar metals and sea water (the electrolyte). Current flow was though the (damp) wood of the hull, i.e. the timber became the conductor. Although only small, this current flow attacked the cellular structure of the timber fibres - in essence, destroying the integrity of the wood near the fitting. I have forgotten if this occurred more at the anode or the cathode . The bonding allowed the bonding wire to become the conductor rather than the timber, thus protecting the timber.

Fast forward to fibreglass hulls and the practice continued (presumably because "this is way it was always done...")

I don't believe there is any strong evidence that is necessary on a fibreglass hull. As others have posted, bonding such fittings is not routinely done in Australia and the UK but apparently still in vogue in the USA. To my knowledge, skin fittings don't degrade appreciably faster Australia and the UK. I don't know the situation in other parts of the world (Europe, Africa, South America, Asia etc).

There may be reasons to bond around extensive use of AC shore power but I don't have the knowledge to make meaningful comment around that aspect although my gut feeling is that it isn't an issue.

[a64pilot]

Two schools of thought, one is to bond everything, my boat is done this way, it’s to protect any underwater metals but not from electrolysis

Second school of thought is if there is no electrical connection, why bond? In other words bond the engine of course etc. but an isolated seacock, what’s the logic there ?

Both schools of thought seem to work.

In my opinion which means nothing, but any kind of lightning protection system is wishful thinking, if some system worked, it would either be required by insurance, or you would get a discount.

The amperage from a lighting strike is enormous, way more that can be carried by any reasonable wire.

[Wotname]

Originally Posted by a64pilot

Two schools of thought, one is to bond everything, my boat is done this way, it’s to protect any underwater metals but not from electrolysis

Second school of thought is if there is no electrical connection, why bond? In other words bond the engine of course etc. but an isolated seacock, what’s the logic there ?

Both schools of thought seem to work.

In my opinion which means nothing, but any kind of lightning protection system is wishful thinking, if some system worked, it would either be required by insurance, or you would get a discount.

The amperage from a lighting strike is enormous, way more that can be carried by any reasonable wire.

Leaving aside lightning aspects (which is entirely different question), yes, both schools of thought apparently work but perhaps only because while bonding does not help, it does't hinder either. In essence, becoming a waste of time, money and effort for a fibreglass hull.

When someone posts an electrically sound argument for the advantages of bonding, I will reconsider my approach .