Has Anyone Broken their Anchor Chain or Stretch Damaged It?

[r_mcphee]

Thank you for starting this thread, we found it very interesting having just had a real surprise when our anchor chain broke while on a flotilla boat in Kefalonia, Greece.

To answer the specific questions:

What boat size, weight and type ?
Bavaria Cruiser 37. 37 foot sailboat guessed weight of about 9 metric tonnes.

What chain Brand ? (eg Acco, unknown brand)
Unknown

What chain type ? (eg Unknown, BBB G40)
Unknown but was galvanised.

What chain size ? (eg 10mm 7/16 1/2inch)
8mm

How old was the chain?
Unknown, the boat was 7 years old.

Did it have any rust damage that weakened it?
Yes apparently rusty.

Did it break or stretch ?
It broke at about 40meter point leaving 22 meters on the boat and 40ish meters on the sea bed.

Did the shackle break first before the chain could be stressed ?
The chain broke, not any attachments.


What were the circumstances ? (eg Hurricane, thunderstorm with a large swells, jammed under rock and gave it some under power).

The weather was a high pressure day, light winds no clouds and 40 deg C. The anchor was being set in 8meters of water with a sandy bottom for a lunch stop. Once 40 meters of chain had been let out while in slow reverse, the chain went taught. Gradually the reverse power was increased to about 1500 rpm on a 30hp sail drive system. A few seconds later the chain went loose and the boat started moving. The decision was made to re set the anchor, so the chain was wound back in and found to be mostly missing.

What was the wind speed ? About 3 knots

Did the boat get damaged ? No

The interesting extra fact was that the chain broke at the point where some markers had been added to the chain. There were several yellow tie wraps attached to the chain on each of the 5 remaining links at the point of the break. These were presumably added to help show how much chain had been deployed. Watching how these markers travelled through the windlass gypsy suggests a reason for the failure. The chain “clattered” through the gypsy when accommodating the tie wrap markers suggesting there was unusual wear on the chain at these points.

Our conclusion was that makeshift markers on the chain should be avoided and proper markers used to ensure the chain travels correctly through the gypsy.

We couldn’t quite get to the chain free diving in order to recover it, so the chain and anchor locations were marked on GPS for later recovery by the company and the holiday continued with the kedge and rope system with manual recovery each time.

[Kettlewell]

Never had a failure in anchor chain in more than 40 years of cruising, but I have heard of many mooring chain failures due to corrosion. And, those are huge chains. I retire my chain when it starts to get corroded due to the difficulty of getting it re-galvanized. I would never trust my boat to no-name cheapo chain. Corrosion is the biggest factor I think. Snatch loads should be avoided with the use of appropriate snubbers. I suspect many of us do not have enough length on our snubbers in extreme conditions. That's one reason I am thinking of going to a mixed rode with a shorter length of chain backed up by nylon. With that setup your snubber is easily and automatically lengthened when you need it since most of us will let out more rode in higher winds.