Whew! That was close!

[ArmyDaveNY]

I know of some people installing a battery on/off switch on the negative cable of their winndlass battery, thus isolating the system (assuming proper wiring) and preventing stray current from the windlass battery.

I am not sure if you have a battery near and only for the windlass, but if you do you may wish to try this.

[John Casey]

Originally Posted by Jim Cate

Was that article perhaps in the National Enquirer?

And BTW, "crystal radios" don't require external power...

Jim

True enough. Google "foxhole radio" for another take.

[belizesailor]

Originally Posted by Ecos

Belive it or not, there is no way to re-cycle batteries in much of MX and central America.
I'm going to guess that the generator was grounded to the boat. The stemhead fitting made contact with the chain. The stainless steel at the end was enough resistance to cause the chain to burn through with the poor contacts at the end of the chain.

Sure there is...Chatarreros (junk men)! They pretty well for batteries too! 😆

[bensolomon]

Toddster....great power point and explanation!

[boatpoker]

Originally Posted by a64pilot

Steel is essentially Iron is it not?

Many different types/grades of steel and a few different irons, many (most) with slightly different voltage potentials which is the critical issue in any corrosion involving galvanism. Since we are dealing with microvolts, even the smallest difference ..... well, can make a difference

[Sailor647]

After reading everyone's helpful comments, stray current makes the most sense, so we decided to take advantage of time in the marina to do some more testing.

Since we were at anchor, the stray current was probably ours. The closest electrical device to the anchor chain is the windlass, and it is not connected to the bonding system, but is connected to the boat's grounding system.

We removed the plastic covers to the Maxwell foot switches. They are both clean and dry, no corrosion. We also took the cover off the solenoid box in the chain locker and looked inside. Clean and dry, no corrosion.

We borrowed a fellow cruisers' silver/silver chloride half cell and tested the windlass. We got readings floating between 210-260 mV (positive) on the windlass clutch nut, the gypsy, and the chain that was touching the gypsy. (See pic.) No reading - as in 0 - on other parts of the stainless steel windlass including the capstan drum or the base, or on the chain next to the anchor which is about 12" away. (And a zero reading from the aluminum deck cleat, stainless bow roller, and stainless stanchion.)

We then disconnected every wire from the windlass (positive, negative, ground, solenoids, etc) and STILL got that reading. (See pic.) Any wise folks out there than can interpret the results for us? Do electric windlasses store energy?

The negative cable wasn't as tight as it should be and had very slight corrosion, so we cut the cable end and installed a new lug and shrink tube. At the new cut, the wire was shiny copper and in good condition. We also replaced the terminal on the ground wire (also shrink tubed) because it was over-sized.

The DC Amp Meter at the nav station shows no draw when everything is turned off. The next time we anchor, we'll turn everything off except power to the windlass and see if there is any draw. We also plan to turn off the breaker for the windlass while at anchor, something we haven't done in the past.

After cleaning up the wire ends and tightening it all up, an ammeter was clamped on each wire individually (and as a group) going to the windlass. Nada. No measurable current.

The multimeter also showed no stray current at the windless.

The brown coating on the interior windlass pic is a marine grade corosion inhibitor made by CRC. Any chance the coating is allowing current to jump across the terminals in a damp sea environment? The chain locker does get wet, which is why the coating was applied.

So, either the windlass wasn't the source of the stray current, or we fixed it by fixing the negative lug connection.

I think we'll also invest in 10 feet of stainless chain for the end just because it was recommended and can't hurt. Plus, it will look impressive coming out of the chain locker when we pull up to the dock. lol

What are we missing? Thanks again!

[toddster8]

Originally Posted by Jim Cate

Was that article perhaps in the National Enquirer?

And BTW, "crystal radios" don't require external power...

Jim

As further aside: Actually, the reactor compartments of our nuclear submarines are cut out and barged up the Columbia River to the Hanford Reservation, where they are stacked in neat rows in an enormous open pit. It is left open so that they can be verified by satellite, as part of various arms control treaties. You can fly there with Google Earth and count them yourself. ( 46°33'56.67"N 119°31'9.80"W) Back when I worked on the "Lazy H Ranch" and had the proper clearances, I drove down into the pit a couple of times. Truly Brobdingnagian. I also biked daily past the barge landing and the ludicrous big transport dolly that was used to haul them out into the desert.

[Paul L]

Originally Posted by Sailor647

After reading everyone's helpful comments, stray current makes the most sense, so we decided to take advantage of time in the marina to do some more testing.

Since we were at anchor, the stray current was probably ours. The closest electrical device to the anchor chain is the windlass, and it is not connected to the bonding system, but is connected to the boat's grounding system.

We removed the plastic covers to the Maxwell foot switches. They are both clean and dry, no corrosion. We also took the cover off the solenoid box in the chain locker and looked inside. Clean and dry, no corrosion.

We borrowed a fellow cruisers' silver/silver chloride half cell and tested the windlass. We got readings floating between 210-260 mV (positive) on the windlass clutch nut, the gypsy, and the chain that was touching the gypsy. (See pic.) No reading - as in 0 - on other parts of the stainless steel windlass including the capstan drum or the base, or on the chain next to the anchor which is about 12" away. (And a zero reading from the aluminum deck cleat, stainless bow roller, and stainless stanchion.)
.......!

The half-cell reading should be negative. Try taking a reading on your prop shaft.
Is there any voltage reading between the gypsy and the ships ground at the battery(or close to it) when all cables are connected to the windlass?
Any reading when the windlass is activated?

[waterman46]

I think the degradation at the end of the chain can't be caused by stray current. The boat, and other boats in the vicinity, and all those anchor chains above the anchors, are all sitting in a pretty great conducting bath called salt water. Any stray current from other parts of the boat or other boats should conduct through the water to the UPPER part of the chain(s).

Seems to be simple reaction between SS swivel and Zinc galvanizing then the steel chain causing this. BTW I notice after many years that I see the zinc has disappeared from the last two links of my anchor chain, on the one anchor where I am using a SS shackle. I'll just cut off those links and replace with a galvanized shackle.

Another good reason to feel GOOD about not having one of those beautiful SS anchors perched on the bow, that are so impressive.

[Paul L]

Originally Posted by waterman46

I think the degradation at the end of the chain can't be caused by stray current. The boat, and other boats in the vicinity, and all those anchor chains above the anchors, are all sitting in a pretty great conducting bath called salt water. Any stray current from other parts of the boat or other boats should conduct through the water to the UPPER part of the chain(s).

Seems to be simple reaction between SS swivel and Zinc galvanizing then the steel chain causing this. BTW I notice after many years that I see the zinc has disappeared from the last two links of my anchor chain, on the one anchor where I am using a SS shackle. I'll just cut off those links and replace with a galvanized shackle.

Another good reason to feel GOOD about not having one of those beautiful SS anchors perched on the bow, that are so impressive.

Your basic logic sounds good. I just don't see how this could happen in two weeks. Two years, maybe.

[boat driver]

I am not sure of the location conditions of the anchorage, but personnel experience/observations in the Chesapeake Bay followed by some investigation:

Moorings in salt water tend to fail from electrolysis (not galvanic corrosion) corrosion at the bottom of the chain with the worse/weakest link closest to the anchor. In fresh water, the corrosion happens at the surface links and works towards the anchor.

Electrolysis uses a direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction,
DC current is chemically separating the ore when immersed in a liquid electrolyte.

The effect simple explanation is the anchor buried in the mud becomes the battery and the water is the ionic compound. The salt water, particularly at depth, provides the conduction. In fresh water (less conductive) the effect is at the top of the water column (conductive liquid).

The bottom mud and metal type, surrounding pile of cast-off iron scrap probably set this battery up with a semi-perfect DC flow chart.
If the anchor was moved 1/2 mile away, the effect would probably be much less (but not gone) .

The stainless anchor and iron chain probably did not interact via galvanic corrosion, just the chain was the lesser of the noble metals. Not knowing the surrounding environment, if a underground power source was in the vicinity, the anchor would be the contact surface and the chain would be the wire to the surface.

The effect happens on ship anchors, anchored oil rigs, bridge piles, underground metal pipe. In most cases each has various methods of preventing this effect.

The only suggestion would be consider anchoring without a chain to the anchor, or invest in a method to electrically isolate the chain from the anchor . (hard rubber coated shackles at shank, nylon strop, etc. )

Most important, periodically heave the anchor and inspect.

[boatpoker]

Originally Posted by boat driver

Moorings in salt water tend to fail from electrolysis (not galvanic corrosion)

Electrolysis uses a direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction, DC current is chemically separating the ore when immersed in a liquid electrolyte.

The effect simple explanation is the anchor buried in the mud becomes the battery and the water is the ionic compound.

To anyone capable of reasonable reading comprehension I recommend you look up the definitions of "ionic compound" and "electrolysis" (on a recognized science based website) Then disregard this entire quoted post.

While my posts on this thread were clearly labelled as WAG, This and many other posts are stated as established fact, do a disservice to anyone who thinks they can actually learn anything of this topic here .... unsubscribed.

[Exile]

Boatpoker recently provided this information in another thread, so hopefully he won't mind my linking it here:

Electrolysis, Stray Current, Galvanic Corrosion on boats explained

[boat driver]

Boatpoker,
very sorry that my wording, which I will refrain from detailing my reasons, excited your response. All said, lets get to the logic of the discussion- from the info provided-
anchored two weeks- first five links corroded and eaten up significantly.
So start with post by sailmonkey #36- this is very real - ask NY Taxi Cab (the boats) and Gladding Hearn/ fernstrum companies.
That was excess of a million dollar law suit about microbes and electrolysis.

If the source of DC power was the windless, then the logic would be that it would expose itself at the water surface as it completed the ground loop- and as well as similar amount of discoloration/erosion would be found somewhere in the vessel underwater metal or thru the grounding system. ? Therefore- having it at the mud level- it would make logic that it was not a self inflicted boat source.

so that leaves us with two thoughts- an undermud source (near by power source) or a mud/microbe that carries a dc current. The rest is simple- the chain becomes the easiest and most direct source to the water which then conducts the voltage to the nearby pile of iron?/ which in turn closes the loop. I am not sure where your post of galvanic corrosion fits into electrolysis, but the SS anchor/ galvanized chain did not corrode due to dissimilar metals. for simple put- if the power from the windless had to transverse from the chain to the SS anchor after passing thru the very conductive salt water it would have created as well some pitting on the anchor and swivel (they are very close noble metals),

My choice of words may have been taken out of context, but my emphasis was more that this is not dissimilar metals but the application of electrical power to an alloy in a liquid.
I would suggest that a simple experiment would be take an anchor and chain on a mooring to same location and observe after two weeks the result. Be sure to set the anchor fully into the mud- it needs the full bulk below the mud level. The result may provide two answers- possibly eliminate the windless as culprit and suggest a harbor note not to anchor in that location.

[Fuss]

Originally Posted by Sailor647

Good morning, everyone.



We cut the five links off and re-attached the chain. Pics attached.



Lucky Lion was the other boat that lost their anchor in the same location we did. They were at anchor and went adrift. I asked a fellow on the dock about a possible cause and he said, "Well.... his gear is a little suspect, the condition of it isn't good. He only has a 22 pound anchor and 10 feet of chain on the rode. Instead of buying new chain, he had the old piece re-galvanized."



We also found out that the yellow buoy (near where we anchored) is not marking a shipwreck, but a "mountain of scrap metal" that was dumped there during the construction of the marina.



I took the photos this morning and will thoroughly inspect the chain each time we pull the anchor.



We are going to test the windlass for voltage, as suggested. And re-install our backup anchor (and rode) back on the bow roller.



If it happens again, I'll be sure to report back.



Thanks again for all the help. We really do appreciate it.

Thanks Sailor647 for the photos and feedback that you cut 5 links off. As the problem happened within 2 weeks, can you pull the anchor in 1 week and send us the photos and then the same again in 2 weeks, but try to re-anchor in the original place causing the problem each time.