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Old 24-10-2015, 17:14   #16
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Re: Larger last chain link

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I'm not sure of the breaking strains of various short link chains. I guess they must be more than the weight of the vessels they are used on. I imagine we could safely lift our boats on a crane with our anchor chains. ( I'm not going to try)


Being anchored in 103 knots must have been interesting and a good test!!


I'm not stating anything; just asking

No. Our boat weighs about 18,000 pounds. 5/16 chain will not safely lift it. Maybe 1/2 that and stand back. It not about that, it's about how much pull the boat can exert. 5/16" G-4 has enough strength to hold our boat and that's about 5000 lbs.
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Old 24-10-2015, 20:12   #17
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Re: Larger last chain link

Here are the specifications for G43 windlass chain:

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Old 24-10-2015, 20:28   #18
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Re: Larger last chain link

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A relation had the substantial anchor / bowsprit on his 36' displacement power boat break when freakishly the chain must have caught on an unknown rock and the boat went up on a wave. The chain didn't break but the short anchor roller bow extension did with a crash. It is an ex charter boat built to survey and he had many years at sea in the navy. Insurance was happy to cover it.
The anchor roller, windlass, or bowsprit if there is one should never take the anchoring load when anchoring with all chain. A nylon snubber should be attached to the chain and be taking the load to one or two cleats. This gives stretch which chain doesn't have. Windlasses are not designed for anchoring loads.
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Old 24-10-2015, 22:04   #19
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Re: Larger last chain link

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When the chain is ordered the chain manufacturer can attach a larger link at both ends. You can subsequently ask a welder to do that for you, but the link will need to be galvanised after welding. I would also have some doubts if it will be as strong as a suitable shackle. If the welder is not very careful, the heat will destroy the tempering in the steel forming the larger link.

Unless you are using G7 chain, I am surprised you cannot find a shackle that is suitable. I presume you have looked at the most common solution, which is one of the G8 shackles from Crosby or Green Pin. I use a Crosby G-209A.

While stainless is perhaps not ideal, the Whichard HR series are also often used. They also make titanium shackles although, surprisingly, these are slightly weaker than the HR stainless version.

Hopefully somewhere in that choice of shackles there may be something that is suitable.
In several places I'm finding the working load limit (WLL) of my 1/4 inch chain to be 2600 lbs, and the inside diameter to be 0.41 in.
The WLL of 5/16 G-209 shackle seems to be 3/4 ton, or 1650 lbs. I also found a "Super Strong" shackle with a WLL of 2000 lbs. Neither matches the WLL of the chain. The pin diameter of the 5/16 shackle is 0.38. The pin diameter of a 3/8 shackle, which would have an adequate WLL, is 0.44, so it won't fit.

References
Peerless Industrial Group :: Marine Chain and Accessories :: ACCO Marine Chain :: ACCO Windlass Chains :: ACCO G43 Domestic High Test ISO Chain
http://www.westechrigging.com/r
igging-hardware-shackles-crosby-shackles-g-209-screw-pin-shackles.html
CM Super Strong Screw Pin Shackles from Westech Rigging Supply
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Old 25-10-2015, 00:35   #20
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Re: Larger last chain link

Sorry I find it easier to work in metric. The diameter between links for your 1/4 inch G43 chain (the maximum pin diameter) is 10.41mm (0.41 of an inch as you say). The smallest G-209A Crosby shackle is 3/8 and has a pin diameter of 11.2mm so as you say that will not fit. The smallest Green Pin G8 shackle (or super shackle as they are called) is bigger again. The G-209 comes smaller, but is not a G8 shackle.

You should be able to use the 10mm Wichard HR stainless shackle which has a SWL of 2640kg (5820 lb). If this is too tight The stainless steel 8mm Wichard HR shackle has a SWL of 1760 kg (3880 lb) (but note the SWL only 1/2 the break load. So the break load is a fraction less than your chain for the 8mm version)

Even a well made forged but ordinary stainless Wichard 10mm shackle is fine the SWL is 1520kg. The ratio of SWL to break load is higher (3.5:1) so the break load is still above your chain (5200 kg). This is the option most people would use.

The shackles can be subject to some side loading so going stronger is a good thing if it fits. The dimensions are always a bit variable especially after galvanising so the 10mm Shackle would need a trial fit, but should be OK.

There has been some doubt expressed about using stainless steel especially HR stainless in this application but this looks your best bet. For the ultimate, cost is no concern, option the titanium version is better again. It eliminates the concerns of using HR stainless steel but they are only produced in 10mm (which should just fit) the SWL is actually a bit lower than the HR version at 2160kg which still is almost double your chain SWL. The break load is almost the same as your chain.

Perhaps measure your actual chain with some callipers before ordering the 10mm version.

Edit: if 10 mm does not fit it looks like Wichard are now producing 6 and 8mm titanium versions. The 6mm is too small but the 8mm should be just be OK from a strength viewpoint. The SWL is 1440 kg although the break load once again is only double this so very slightly less than your chain. They are very expensive (as in $200) so really overkill.

Perhaps someone can find a suitable galvanised G8 shackle (or a cheaper titanium version), but a 10mm Wichard HR shackle looks your best bet. It comfortably exceeds the SWL and break load of your chain so there is lots of margin for side loading. A standard forged 10mm stainless shackle is the low cost alternative and would be fine but I would make sure it is a recognised brand with published SWL.

This is a great reference:
https://coxengineering.sharepoint.co...finitions.aspx
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Old 25-10-2015, 11:03   #21
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Re: Larger last chain link

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No. Our boat weighs about 18,000 pounds. 5/16 chain will not safely lift it. Maybe 1/2 that and stand back. It not about that, it's about how much pull the boat can exert. 5/16" G-4 has enough strength to hold our boat and that's about 5000 lbs.
5/16" chain seems to me quite light for an 18,000 boat. That's approximately 8mm which is the same as I have been using on my approx 4,000 lb boat in conjunction with a nylon warp. Now I'm using a longer length of 7 mm which is around 9/32" or round figures, 1/32" smaller than yours ie 10/32
My metric conversions are to the closest standard size.


I was not suggesting you should be able to lift your boat with your chain. Just that is probably the largest possible strain in a highly unlikely situation.


My question was; Has anyone actually had a suitable anchor chain or shackle break in an anchoring situation?
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Old 25-10-2015, 11:28   #22
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Re: Larger last chain link

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My question was; Has anyone actually had a suitable anchor chain or shackle break in an anchoring situation?
This is a good point chain breakages are very rare. However, traditionally cruising boats used what would be regarded, these days, as heavy chain. This was combined with anchors with poor holding power.

The modern trend is lightweight chain with high performance anchors. The reduced chain weight combined with more powerful and reliable anchor winches means the anchor can be increased in size. This further increases the holding power. Thus we are entering a new era of high holding power anchors with relatively small chain. Without careful consideration the connectors that fit this system can end up the weak link. This is especially true if we consider the potential holding power of the anchors in a good substrate (although increasing the size of the anchor is more about holding in poor substrate).

Given tne low cost of the shackle in relation the whole anchoring system it is prudent to make sure this single component is not the limiting factor. The issue is further complicated because with side loading the shackle strength is significantly reduced.

I think the adage used by many cruising boats "fit the largest anchor you can reasonably manage" has a corollary in use the "Best shackle that will fit".
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Old 25-10-2015, 13:38   #23
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Re: Larger last chain link

Here is some info from folks who ought to know:

Basically if you are using 1/4" chain, you are hosed without a bigger end link, although I wonder what the strength is on that link, since I would guess it is placed after tempering. 5/16 up is solvable.

Oversize Links

Shackles, Alloy Steel
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Old 25-10-2015, 13:45   #24
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Re: Larger last chain link

Of interest is that G4 chain WLL is 1/3 of breaking strength and shackles are 1/5, so if a smaller shackle is used with plans for replacement periodically, that might be a reasonable solution for 1/4" chain.
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Old 25-10-2015, 14:07   #25
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Re: Larger last chain link

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Originally Posted by sanibel sailor View Post
Here is some info from folks who ought to know:

Basically if you are using 1/4" chain, you are hosed without a bigger end link, although I wonder what the strength is on that link, since I would guess it is placed after tempering. 5/16 up is solvable.

Oversize Links

Shackles, Alloy Steel
The discussion is interesting though slightly complicated as there are metric chains (I use) or imperial. 7 mm ain't 1/4" and 8 mm ain't 5/16"
I don't think we can easily buy imperial measure chains where I live.

Nuts and bolts in both are readily available. Shackles I think are mostly metric.

The idea of lighter chains with better modern anchors is interesting too.

I expect it's quite likely that we'll need to anchor in +50 knots for a day or 2 in the coming Southern Hemisphere summer (going by the last 45 or so summer cruises) so even though I've just bought a modern anchor I'm not about to lighten my chain. I'll just sleep better as long as others don't drag into me.
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Old 26-10-2015, 06:33   #26
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Re: Larger last chain link

Re the weakest link: I have seen tests where the order seemed nearly always this: the swivel, the shackle, the chain.

In all tests the split links went pop up front.

Sure think if you use a quality shackle on weak chain, the order will be reversed.

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Old 26-10-2015, 07:03   #27
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Larger last chain link

[QUOTE=GrahamHO;

My question was; Has anyone actually had a suitable anchor chain or shackle break in an anchoring situation?[/QUOTE]


Well, if the chain or shackles breaks it is, by definition, not suitable.😃

I have had S/S shackles break - presumably not suitable. Seemed ok before it broke though




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Old 26-10-2015, 10:45   #28
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Re: Larger last chain link

Something must give. Next in the line are the cleat and the deck.

If we were to apply your take then we would build sails, sheets and standing rigging so that nothing breaks. Then you would see the mast go over.

Is it logical then that one element of any system is a 'fuse'. Intentional or otherwise.

Now you get the simple scenario the chain wraps at low tide (over a rock or a coral head) and the hull is lifted by the flood. Now you want your chain to snap or rather watch your boat sunk?

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Old 26-10-2015, 11:12   #29
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Re: Larger last chain link

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Now you get the simple scenario the chain wraps at low tide (over a rock or a coral head) and the hull is lifted by the flood. Now you want your chain to snap or rather watch your boat sunk?
How about letting more chain out? Wouldn't leave boat unattended in a such poor anchorage..

ps. or having a snubber to break..
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Old 26-10-2015, 11:34   #30
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Re: Larger last chain link

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Well, if the chain or shackles breaks it is, by definition, not suitable.😃

I have had S/S shackles break - presumably not suitable. Seemed ok before it broke though




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Most stuff seems OK until it breaks.

But if we are in such extreme anchoring conditions that something is going to break, I'd rather the shackle onto the anchor broke. If the chain broke you'd lose your anchor anyway and a broken shackle will at least save the chain.

Was your SS shackle that broke, on the anchor, or somewhere else on the boat?
I had one of those quick lock shackles bend (not on the anchor) because I didn't click it all the way in place and the pin popped out. My fault entirely.
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