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chain breakage - old thread


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Idlerboat

Posted: Thu Nov 20, 2008 9:02 pm Post subject: chain breakage

 

Ok we all know the relative sizes and strengths of anchor chain and what boat size the manufacturers recommend.

 

....truth or lie time........

 

I want to know if any body has had a chain snap.

 

Need to know boat size, and weight, circumstances, and chain size and type.

 

Dont want conjecture's about cheap this and best that....

 

I want to know if someone has snapped their chain. SIMPLE.

 

 

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David Lackey

Posted: Fri Nov 21, 2008 4:46 am

 

I have chain stretch so that the elongated links no longer fitted the gypsy.

 

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Crew.org.nz(a.k.a. Squid)

Posted: Fri Nov 21, 2008 12:37 pm

 

Two anchors out, one all chain, one rope and chain. The chain was attached via a 3/4inch rope snubber with a chain hook. The rope snubber parted, the chain held (but elongated as above, only a few links but a pain, probably when it took the shock load ).

 

44ft Peterson, Gulf of Papagayo, 60 kns.

 

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idlerboat

Posted: Fri Nov 21, 2008 1:43 pm

 

thanks guys, what size chain link ? 3/8 (10mm) or 8mm bigger/smaller

 

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Crew.org.nz(a.k.a. Squid)

Posted: Fri Nov 21, 2008 1:53 pm

 

Mine was 3/8 being american and all, it was triple b or some letter like that, which ws supposed to be the good stuff. We were tucked in under a cliff and the gusts were coming from every direction. It went quiet for a bit then a big one hit us beam on, we put the rail under (at anchor!!!) and skidded sideways till we got to the end of the warp and she snapped tight, breaking the snotter with a hell of a bang. I wonder if I would have been better off further out, more wind but consistent.

Of course it was 3 am.

 

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idlerboat

Posted: Fri Nov 21, 2008 8:20 pm Post subject:

 

this is very interesting. here and elsewhere I have been getting a heap of replies saying that they distorted the links (making it impossible to use the anchor winch........)......the plot elongates...

 

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Knot Me

Posted: Sat Nov 22, 2008 6:42 am

 

Yes Idlerboat, links stretched to the point of being windlass no-go's are becoming quite common. They have always happened but the cases of it happening are increasing as things are being built to a price point.

 

Actually snapping isn't that common but it does happen. Saw one last week, a 1/2" on a 70fter....ping. Usual cause is using too small a size. People trying to save weight and going down in size too much or import boats (usually out of the US) where they use tiny but higher grade (strength) chains and oversized anchors. All good on a fresh water lakes with no waves but the Hauraki Gulf isn't so kind to them. Big wind and everything is tight, big wave comes along and ..... ping.

 

The 4 most common chain issues currently are -

Stretching or distorting to the point it would fit gypsies. (Assorted reasons but mostly due to the use of 'soft' metals)

Jambing in gypsies (poor calibration)

Quick to rust (low quality galvanising)

and last and only more recent phenomena is the 'Opps forgot to weld that link' problem. Just the random 'lemon' factor from some areas of manufacture.

 

That does exclude one other and the most common by miles problem, 'My mate said' as in My Mate said I need 8mm only to find a cock-up as it was actually a 10mm gypsy. In other words, people just fitting the completely wrong size.

 

The connection between the chain and the anchor is far more likely to be seen failing than the chain though.

 

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wheels

Posted: Sat Nov 22, 2008 9:33 am

 

Hey KM, what sort of loads should we expect 8, 10 and 12mm chain to handle before link distortion and complete failure.

 

Oh and while we are on that subject, remember I need a 10mm Tested D shackle with a 25mm throat.

 

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Ailys Comet

Posted: Sat Nov 22, 2008 10:21 am

 

I took this chain stretch issue seriously enough to invest the extra dosh in the highest quality stuff I could find (courtesy of KM - thanks). If I remember rightly it's Italian, isn't it KM?

 

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Knot Me

Posted: Sat Nov 22, 2008 4:18 pm

 

OK here we go in a brief manner. Just got back from the ballet and off to a concert shortly. There is a lot of technical info really so this is just a quick over view and quite 'general' in nature.

 

Shackles - 99% of the ones in chandlers are made in china and referred to as 'commercial' even though most of the commercial guys don't use them. They are OK generally but some are complete sh*t. Usual issue is what SJB had, crappy threads. Some batches are great, some average and some sh*t. I tend to use the one factory each time so we tend to get 'average to good'.

 

They are knot that strong BUT bare in mind that the failure rate is still low considering the number out there (I buy approx. 20,000 at a time and we aren't the biggest player out there). Things to look for - the holes for the pins are pretty much in the centre and sloppy threads. There is knot much else you can do short of a test programme of some type.

 

We tell people to use tested shackles if they are bigger and/or serious. We prefer the genuine 'Green pin' but the other coloured pins (asian knock-offs) are fine as well. I've knot heard of one failing. They cost a few $ more but have known and tested loads.

 

Swivels - Many are dodgy especially the ones that look like 2 shackles bolted back to back. I have yet to see one that can withing 25% of it's stated break load, some have been trashed at less than 35% of stated break load. There are also the eye-eye type that look similar. Again dodgy. I refuse to sell them even to Riviera owners so that's how spooked I am by them.

 

But there are some that are perfectly fine. They are usually the more 'tubular' shaped ones. Kong made in Italy are fine as are the ones by 'Clarke' with the SWL and chain sizes written on them. I know for a fact the smaller Clarke ones for 6-8mm chain have never failed below 4100kg on the test bed. Grade 40 8mm short link (Maggi is the only G40 in NZ and the stuff AC has) has a break of 4000kg so the swivels are no weaker.

 

But there are some that look similar to the Kong and Clarke except a bit flasher that have issues. I think most have a little Dolphin on them, they are branded in a few ways. They don't have a captive center pin which means they can just un-wind and hello, off you go. They also have insufficent side way pull strength so could open the cheeks under load.

 

This is the issue Burnsco had when they thought their local supplier was too expensive and tried to do their own. To Burnscos credit they did go out of their way to get them all back and sort any issues that come from them, big ups for them on that. They don't use them any more and are well over that so no worries on that account.

 

We recommend swivels on any rope to chain rode that use a 3 strand rope. If you have a spinner of an anchor (Deltas, Sarcas, any bent anchor, danforths are common ones. Recently we've had one or 2 say Rocna as well but in all of our testing we haven't seen that) if can twist the chain up quickly on retrieval and once that happens it can carry on and unlay the rope. Rope unlays, splice falls out then the chain and anchor are doing a Titanic.

 

On a 8 braid is not so important as it is a non-rotating rope. That means you can twist it whatever way you like and the lay would open letting the splice fall out.

 

So yes there is a place for swivels even though many (a lot) use them for no apparent reason. Yes there is some perfectly trust able swivels out there. A good swivel is far far stronger than an average commercial shackle.

 

If on all chain or 8 braid we say try your gear and if twisting or spinning is an issue a swivel can be retro fitted in 2 minutes. Save the money for beer.

 

Chains - A lot of of Asian made are soft and prone to stretch. A 10mm did in 25kts on a 34ft Vindex recently, that should never ever be able to happen. They build to a price and have wobbly metal quality, knot all but generally speaking. Which is which? That's the big problem, it's damn near impossible for the average punter to know until it all goes bad.

 

Example - someone tried to sell us some 20mm mooring chain out of asia. It measured identical to our Maggi (Italy) chain. 1 meter of the Maggi chain weighs 8.4kg, that asian weight 7.2kg for the same length. When we cut the asian open it had voids, one about the size of a pea.

 

The price difference between Maggi, PWB and Serifini (last 2 made in Aussie) and the Asian chains at the retail end is bugger all considering the probable huge quality difference. The asian chains should be a pile cheaper than they are been sold for, some are running very large margins so screw them, they have room to move and still smile as they take your dosh.

 

All of this doesn't apply too much to the smaller boats as they just don't put the loads on their system to find the danger area. Yes I know one anchor seller will try to say you'll get massive loads on your gear bit reality is that 99% of the smaller end just don't. I'd say if you need a 8mm chain or larger you should be starting to look closer at all the bits. At 12mm chain size look a lot harder.

 

And working on the 'it costs more so it must be better' theory is knot good. Sure the good gear does usually cost more but as most retailers have very very little going on zero technical knowledge of anchoring systems, you just never know. That statement can often exclude the small ma and pa type outlets, they tend to have to know more and work hard for your custom. The bigger ones often just lure you in with a lost leader and then give you it right up the botty on everything else.

 

If you need gear like this ask questions and if the answers are vague or just don't sound right be a bit nervous. Ask "what country is it made in?', they should know on mission critical gear.

 

What have I forgotten?

 

Disclaimer - We do sell some chain made in asia but knot one inch of it is short link anchor chain, it's more for walking the dog or fences. We also sell all the anchors mentioned above. Just trying to be open here. If something is good we will say so even if it isn't ours. And yes we do sell one or 2 things we regard as crap but we will tell you that if you ask for one, which does confuse the hell out of some customers sometimes

 

 

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