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Old 02-05-2015, 12:47   #1
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Should an anchor chain be connected to the earth bonding system?

The anchor locker on my Grand Banks 42 has a bonding wire at the bottom, its not connected to any part or any thing in the locker. Should it be bolted to the anchor chain as well as the chain being secured to the inside of the locker by a rope?

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Old 02-05-2015, 12:53   #2
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Re: Should an anchor chain be connected to the earth bonding system?

Don't connect the anchor or the chain, the last thing you want is electrons taking all that nice galv off your chain.

Wonder if the bonding wire is left over from a previous owner who used it to connect to an extra anode when stationary?

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Old 02-05-2015, 13:03   #3
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Re: Should an anchor chain be connected to the earth bonding system?

Hi Pete 7, thanks for the advice. I am the original owner of the boat buying her new in 2003, ive let it lie there in the locker since new so its been in contact with the chain all the time but not connected to it firmly by way of a nut and bolt, this could be why my chain has corroded and is now being replaced.

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Old 04-05-2015, 03:43   #4
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Re: Should an anchor chain be connected to the earth bonding system?

Pete 7 advised me not to connect the bonding wire to my anchor chain but i have checked inside the anchor locker of another Grand Banks 42 and the bonding wire in that boat is bolted to the metal eye that you secure the anchor to. So Grand Banks seem to intentionally earth the anchor chain.

This leaves me confused, does anyone have any more thoughts on this one?

Brian

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Old 04-05-2015, 10:49   #5
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Re: Should an anchor chain be connected to the earth bonding system?

The metal eye that you "secure" the anchor to can be bonded because its hardware that is bolted to the bolt.
It's not the chain that's being bonded, it's the hardware securing the anchor while not in use.



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Old 04-05-2015, 10:53   #6
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Re: Should an anchor chain be connected to the earth bonding system?

Bond the attachment point to the hull, then use a rope splice to connect the chain to the hull anchor point.
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Old 04-05-2015, 10:53   #7
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Re: Should an anchor chain be connected to the earth bonding system?

Your chain corroded because it probably was put in the locker without a fresh water wash down before stowage.
Galvanizing is a coating, as the chain gets scratches, it will lose protection, wash down is important as well dryer stowage within the locker.
Drain holes to the outside of the hull or the bilge are the common theme.


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Old 04-05-2015, 13:24   #8
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Re: Should an anchor chain be connected to the earth bonding system?

Inspection shows that my chain is grounded to the boat. The chain passes over the electrically operated windlass wildcat which is tied to the boat ground. When anchored the chain also passes through the bow fitting (that it often times touches) which is also grounded. When the anchor is stored the anchor touches the bow fitting and the chain is attached to the anchor. It looks to me like I can't un-ground the chain, so why not give it a good ground?
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Old 04-05-2015, 13:38   #9
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Re: Should an anchor chain be connected to the earth bonding system?

Are you sure the windless is grounded / bonded. The issue is the zinc used for galvanizing the chain and anchor (assuming its not SS). With a bonded anchor chain, that zinc coating protecting the chain will get used up as it's a anode to steel. It does this anyway for the steel chain, but tie it to the boats bond and it would increase the de-zincing of the galvanized chain. It depends on lots of variables but to me it seems counter productive to use an expensive chain as a zinc anode.
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Old 04-05-2015, 18:01   #10
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Re: Should an anchor chain be connected to the earth bonding system?

Quote:
Originally Posted by sailorchic34 View Post
Are you sure the windless is grounded / bonded. The issue is the zinc used for galvanizing the chain and anchor (assuming its not SS). With a bonded anchor chain, that zinc coating protecting the chain will get used up as it's a anode to steel. It does this anyway for the steel chain, but tie it to the boats bond and it would increase the de-zincing of the galvanized chain. It depends on lots of variables but to me it seems counter productive to use an expensive chain as a zinc anode.
Yes, the windlass is grounded. A wire runs from the windlass gear case to the boat ground system (engine, copper plate in the water, all the underwater bronze, stays...). I also suspect, but do not know for sure, that the negative 12V motor power wire is connected to the windlass motor case providing another ground path (and to force a circuit breaker trip should a short occur from the internal wiring to the motor case).

I am not sure of the safety of having the anchor chain in the water and not connected to the boat ground system in the case of a lightning strike. I would think a low resistance path would be desirable to prevent arcing at the bow.

Would would not a couple of hundred pounds of iron chain in the chain locker rate as a large metal object needing to be connected to the boat ground for lightning flash over protection?

As I said the bow fitting (anchor roller and forestay chainplate) is grounded and thus grounds the chain whenever they touch. With the chain tension taken up with the rope snubber, that is the usual case. The slack chain drops down on the stainless steel.

I realize the potential problem with the anchor chain zinc. I started this thread which got no replies.
http://www.cruisersforum.com/forums/...ing-66756.html

In talking to others about the use of expensive and thin chain galvanizing for anodic protection rather than cheap and big hunks of zinc anode, it was pointed out to me that the distance from the zinc galvanizing on the anchor and chain to the underwater bronze was much much greater than the distance from the anodes to the underwater bronze. That would make the anchor chain galvanizing much less effective at protecting the bronze (read it would not dissolve as fast).

I don't know the "right" answer to all this... But, I do know that we have had the boat at anchor for 150+ days per year for each of the last 8 years. We re-galvanize the chains at the first sign of rust stains on the deck. That is once every three years for the primary anchor chain and once in 8 years for the secondary. The anchors themselves (a 44 lb Bruce which is used 98% of the time and a 35 lb Delta which is used 3% of the time) have each been re-galvanized once in the 11 years we have owned the boat. We will have the primary chain re-galvanized when we get home this summer. It needs it again; its three years are up. The zinc has been lost in the areas where each link bears on its neighbors, so I suspect this is mostly wear.

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Old 04-05-2015, 18:29   #11
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Re: Should an anchor chain be connected to the earth bonding system?

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Originally Posted by wsmurdoch View Post
Would would not a couple of hundred pounds of iron chain in the chain locker rate as a large metal object needing to be connected to the boat ground for lightning flash over protection?

In talking to others about the use of expensive and thin chain galvanizing for anodic protection rather than cheap and big hunks of zinc anode, it was pointed out to me that the distance from the zinc galvanizing on the anchor and chain to the underwater bronze was much much greater than the distance from the anodes to the underwater bronze. That would make the anchor chain galvanizing much less effective at protecting the bronze (read it would not dissolve as fast).

I don't know the "right" answer to all this... But, I do know that we have had the boat at anchor for 150+ days per year for each of the last 8 years. We re-galvanize the chains at the first sign of rust stains on the deck. That is once every three years for the primary anchor chain and once in 8 years for the secondary. The anchors themselves (a 44 lb Bruce which is used 98% of the time and a 35 lb Delta which is used 3% of the time) have each been re-galvanized once in the 11 years we have owned the boat. We will have the primary chain re-galvanized when we get home this summer. It needs it again; its three years are up. The zinc has been lost in the areas where each link bears on its neighbors, so I suspect this is mostly wear.

Irish Eyes to the Bahamas
For lightning, the anchor chain provides a path via the forward stay and furling foil. to chain to earth. The bonding wire would be somewhat undersized for lightning. So the anchor chain will provide some lightning protection regardless of if the system is bonded or not.

With a bonded boat the anchor chain is in circuit with other metals. Distance is less of an issue for distances under 200 feet. If it's connected electrically it's in circuit and the zinc of the chain will be part of the anode system. There will be some metal loss and between the links would be the first to go.

Bonding works well when everything is bonded and new. Its somewhat problematic after 10-15 years when wires and connections get corroded. Myself I would not bond the anchor windless or chainplates up.
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Old 09-05-2015, 00:09   #12
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Re: Should an anchor chain be connected to the earth bonding system?

Ive now had a reply to the question about bonding the anchor chain bitter end from the technical Dept of Grand Banks the builder of my boat, its set out below for you.
Im happy with the reply, any comments?

Brian

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b) The answer to your question about bonding the bitter end is more complex. Here it is, in verbatim, from the engineers.
The galvanizing will protect the metal under it. It is not sacrificing for other metal. We are talking about galvanic voltage of 200mV to 500 mV. It requires very low resistance between each part. Sometimes even screw fittings are not tight enough . The chain links are only resting on each other the resistance can easily be a few ohms between them . Here we are talking about less than 1 ohm of resistance for galvanic corrosion. On the other hand psychologically if Brian feels better to remove the bonding at the bitter end we have no objection for him to do so.

I believe for those windlass with insulated return need to be bonded. Bonding will protect in case of a short circuit to ground and also help to discharge static electricity during dry weather. There is no issue with the chain losing galvanizing. The chain is in contact with the gypsy only the gypsy is connected to the input via gears in a oil bath. The lube oil in itself is an insulator . This case is analogous to engine gear box due to the oil we need to bond the shaft via a carbon brush or the shaft needs to have its own zinc.

I hope that the above answers your questions.
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