Whew! That was close!

[Paul L]

You could measure voltage differentials with DVM at the windlass, as a first check.

[senormechanico]

See Post 11.

[Fuss]

The good thing is that now you are aware of a potential problem.
Just cut the links off and monitor closely while doing similar anchoring/activities over the next 4 weeks. Then report back here whether the new links had a similar problem or showed any signs of corrosion.
This way we will all learn something and don't need to keep guessing.

[Sailor647]

Below is the response from Ultra Anchor:

Hello,

It is nice to hear that you are happy with your ULTRA Anchor.

So far this is the worst electro corrosion issue we had ever seen. Our experiences tell us that this issue is actually because the ULTRA Anchor is one of its [a] kind - it buries its whole shank with some part of chain. Once it is forced [stressed] there is extra friction on these links connected to the swivel. In your case these 5 links.

Since, dissimilar metals reaction is limited by the two connecting parts, it should have been limited with [to] the first link.

However, I can clearly see that you had two problems at the same time;

1.Dissimilar metals reaction happened at the first link. The electro corrosion is not that easy to describe however once these metals stay in sea water for a long time like two weeks and, by chance if an electricity takes place on the system, it might happen very fast. This is a very low possibility, but here it clearly happened.

2.The other 4 links also looks rusted because ULTRA buried them under sea bottom so the extra friction wore the galvanization off and they are rusted.

You have two options;

1.You can cut these 5 links off and keep on using this system be checking your chain after each anchoring.

2.You can put 10 feet of stainless steel chain in between your swivel and chain. This way the friction problem is solved 100% because stainless steel chain doesn’t get rusted by friction. On the other hand, since we move the dissimilar metal connection point away from stainless steel mass, the electro corrosion problem will also be solved for 90%.

Thanks
Erkutay Yucel
Ultra Marine West

[hpeer]

I’ll just share some of my observations.

1. I agree with Ultra it is not a mechanical issue, the metal loss is on the outside of the link, not wearing away on the bearing surface. Just stating the obvious.

2. We have 2 Steel boats. I’m finding it very common to have corrosion/rust/loss of metal, serious stuff, frequently, when we have SS near but imperfectly bonded to mild Steel. More and more I am moving to welding any SS to the mild Steel as this seems to stop the issue 100%.

I’ve even seen it between two bits of SIMILAR metal. For example our bow sprit was perfect EXCEPT exactly where the anchor flukes layer closest (but not touching) the sprit. That was an extreme case. More common is that some SS hardware was attached to the Steel, perhaps some attempt was made to isolate it, and I will have a rust spot 1/2” to 1-1/2” away.

It has happened too many times so there is clearly something going on. I know of one other gentleman who has written of the same problem on metal boats.

I’ve no idea if this is related to your issue or not. It sounds to potentially have some similarities.

A not cheap solution would be to change to a non-SS anchor such as a Mantus.

I would cut out the bad links and keep a close eye on it. If it repeats, and you have no better solution, I would replace my anchor with a Mantus and then continue to monitor hoping it does not repeat. I recommend the Mantus because, should it NOT, fix the issue it knocks down into a fairly flat storable configuration and you could keep it as a spare. Also it is, or was, the least expensive of the cohort and ships knocked down so shipping is less.

Good luck.

[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.

[noelex 77]

Originally Posted by Sailor647

The anchor chain was last thoroughly inspected in La Paz before we crossed the sea, on December 23.

If the corrosion has occurred this rapidly, the only possibility is stray current corrosion. I think other potential causes such as dissimilar metal corrosion would not present with anything like this speed.

The electrical system is to blame, in my view. Tracking down these problems is difficult, but it is worthwhile to do this. The problem may be intermittent. Links of chain are easily replaced/removed, but the same problem could attack other underwater metals. As you have seen the attack can be very rapid.

As an interim measure I would isolate both the positive and negative supply to the windlass and autopilot (as these tend to be the pieces of equipment that give rise to the most frequent problems of this type) when it not in use

[Greg Mason]

As an aside, we often marked our anchor with a separate line and float. If ever there was a disconnection, the anchor could always be retrieved, and would mark the original anchor location for other vessels.

[bil56]

@sailor647 :
first, what says your battery monitor (or multimeter) ?

[fatherchronica]

We have hidden many treasures under the sea, as the eternal sea has always had room to take one more hit for the team. All the DDT left in the factory in California was dumped between Long Beach and Catalina in the 1970's. Somewhere I have an article I cut from a newspaper once telling how the Navy scuttled 29 nuclear submarines, fuel intact, off the Mendocino coast. There could be anything you can imagine thrown away in the ocean. On a side note, I was remodeling a house once that was two years old. When we were sawcutting the patio slab to begin digging new footings we smelled natural gas and thought we had cut the gas line to the BBQ. I broke up the slab with a sledge hammer and found the two year old wrapped, black pipe, gas line completely disintegrated by rust, where I could crush the fittings and pipe with my fingers. I finally deduced that it was due to stray current. The owners son in law was an executive for a company that made commercial landscape lighting. The backyard had over a hundred low voltage lights in it with unprotected wire nut connections. There could be an underwater cable there that is affecting the metal in the anchorage. A friend of mine told me that as a kid he built a radio, but his parents would not let him plug it in, to save on the electrical bill. So he climbed two neighborhood power poles and hung a wire beneath the power line and used the stray current to power his crystal radio. But I digress, and ramble at the same time. I imagine someone could find a way to measure if the were any current down there. And if electricity is not the culprit I would avoid eating filter feeders and bottom dwelling sealife from that particular anchorage.

[Chuck Hawley]

I have two thoughts on the galvanized chain issue:

1. This is a really good thread, and is the reason that I look forward to getting my Cruisers' Forum email every morning. Positive, clever, informative.

2. I would love to see this "experiment" repeated with the fresh chain, in the same or similar location, perhaps only lasting 8-10 days. However, I would put a piece of slack Spectra or similar line between the chain perhaps 5' from the anchor and the anchor so that there was a "safety" if the chain were to become compromised again.

I know such experimentation has inherent risk, but I am dying to know if the issue can be duplicated.

Cheers,

Chuck

[fatherchronica]

To Chuck, maybe someone with an over insured boat who is through cruising could anchor there and make his boat a test platform.

[John Casey]

Great post. Following.

[Jim Cate]

Somewhere I have an article I cut from a newspaper once telling how the Navy scuttled 29 nuclear submarines, fuel intact, off the Mendocino coast.

Was that article perhaps in the National Enquirer?

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

Jim

[buzzstar]

I am not an expert, but it looks like there is more information in the photo than has been discussed. While there is corrosion on several nearby links, it sure seems the damage is concentrated on two links, probably where they were touching each other. Was there something else at or very near that point, while the anchor was on the bottom, that would have been the cause?