Anyone ever broken an anchor chain?

[charles_reed]

I say - that's a bit extreme isn't it - especially as he never even inferred it.
Still, we see what we want to see...

 

[ldenisov]

Just wondered. I've been reading the very authoritative posts in the other threads about anchor chain where strength is being much discussed.

But does anyone ever get to the stage where there is a possibility their chain might break?

I had the 10mm chain broke - an old one 12 years old+ of unknown origin at Palma de Mallorca 2 days ago. Nothing special , winds 12-13kts. The chain broke about 4m under the boat. Luckily we recovered the anchor and the old chain piece of 25m. The depth was 5m so we could find the chain and the anchor easily. It looks like one ring was not the proper quality or had a time-crack..... Now relacing the whole chain to feel better about it.

 

[Arcady]

I've seen it happen: small mobo anchored close to beach, ferry passed along channel, mobo was at exact focus of wave sweeping along beach from both ends, mobo lifted several feet vertically, chain snapped. I do think it was the chain and not the shackle, but no one bothered to do any close examining.

I saw precisely this happen many years ago to a 28’ motorboat on 8mm chain.

 

[srm]

On a 26ft catamaran I had sold in the autumn (my first boat so nearly 50 years ago). New owner left her on 1/4inch chain + danforth and 3/8 chain plus 35lb CQR. Fairly sheltered anchorage with sticky mud so anchors were probably well buried after a few Shetland winter gales. When he came to move the boat in the spring the 1/4 inch chain was broken about a foot from the bow roller and the links back to the roller were all elongated. We suspected the cause was one of his chains being snagged by a workboat.

 

[Macka1706]

The failure I quoted in #4 was a French chain, but the owner of the chain did not divulge the manufacturer. The chain was newish and the picture I saw looked new chain as the gal looked intact. A number of other posts suggest maybe there was a complete batch with poor welds. Batches can be 1,000m. I note that there is an anecdotal comment of poor Italian chain, Aqua - which is Maggi and Jimmy Green. As mentioned these failures should be picked up, I think, if the chain was Proof Tested which is common conducted as part of the production process. And if Proof Testing is part of the production process it does seem one cheap way of ensuring the chain you buy meets some of its specified attributes. The other cheap way is to follow Vyv's one link test.

To stretch chain such that the links lock, or will not pass through the gypsy implies you are well within 40% of minimal break strength. Typically chains will stretch, permanently, about 15% at failure. But you would need to load to 60% of break strength before the chain starts to stretch, which for 8mm G30 is about 1.5t. To stretch and lock you need to be very near failure. I'm not sure how much stretch will result in gypsy incompatibility.

On the basis a chain is good you really need a very significant load to stretch a chain.

The Americans have an industry standard, G30, G43 and G70, for total stretch of chain at failure of 15%. Interestingly, given its reputation for being brittle, they have another standard for G80, G100 and G120 of 20%.

Jonathan

Hey.
We've done double lifts on cranes in power stations and refinery's of up to 250t per hook. Never a problem. on std lifting chains. SHORT link UNgalv. ALLOY Steel blend.The only chains I'vr ever SEEN stretched. were when we (smack.Smack) used one of our older single lifting chain from front box for towing something out of the mud on Pipelines and sites. I used to go into
refinery every 5 yrs to lift and replace any worn Tanker Mooring chains. (near 1/2 ton per link them mothers). Used to get several sugar bags of HUGE 1/2 kilo each Mussels off them. Warm water in inaccessible to public boat area.
Never saw one of them chains anything but worn on coupling contact surfaces. even with the thousands of tons on each In often up to 40knots along that coastline. 80+ miles to open waters. 46 miles across widest point. No searoom to cover 3 day blows off the Antarctic..

 

[chwarae]

Not sure about chain,but the anchor swivel is definitely suspect. Viv Cox provides very good advice.