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Old 28-04-2013, 22:54   #1
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More work: soft shackles

Pfff... doing everything yourself is tiring now and then Today, I studied soft shackles in their different forms, how strong they are etc. My conclusion is that the time to start using these is now, as my stainless shackles are getting old...

I made three shackles using three different lines:

1. 1/8" Samsom Amsteel Blue,in gray at 2,500lb breaking strength
2. 3/16" New England Endura 12 in white at 5,800lb breaking strength
3. 1/4" Samsom Amsteel Blue, in blue at 8,600lb breaking strength

The theoretical strength of these is 4 times the strength of the line used, as there are 4 strands between load and anchor point. However, the diamond knot that is used as a stopper almost loses 75% of the strength again so that minimum breaking load is only just over 100% of line strength. Tests show between 103% and 120%. So it's safe to go for strength equal as the strength of the line used.

Example: my jib sheets are New England Regatta Braid 1/2" @ 7,000 lb breaking strength. The 3/16" shackle, even though strong enough for the jib, is not as strong as the sheet used so I should go for the 1/4" shackle which is much stronger. This allows me to splice my sheets and attach them with the soft shackle to the jib clew. I can do that smartly so that the diamond knot sits inside the clew so that it will never hang up on rigging again.

But the main thing is to replace stainless steel shackles of-course. Let check standard short D-shackles from Wichard for some often used diameters:

5/32" pin: 1,550lb breaking load
3/16" pin: 2,200lb breaking load
1/4" pin: 3,525lb breaking load
5/16" pin: 5,950lb breaking load

The first two can be replaced with the soft shackle from 1/8" rope and the next two by the soft shackle from 3/16" rope because those 150lb are lost in safety factors.

I made the 1/8" and 1/4" Amsteel shackles as conventional ones, here are some pictures of the one from 1/8" rope:




I think these pictures show pretty well how this works. The diameter of the closed shackle material is 5/32" or 4mm and is a 1/8" with another 1/8" inside as a core. It's small. The little blue lanyard is to pull the shackle open and is Marlow #4 whipping twine.

Next thing is this info I found on-line about an improved version and I made that in 3/16" Endura 12. This construction ends up as 3/8" or 9.5mm thick. Here is a similar photo series that shows the difference; basically, the whipping halfway is replaced by a brummel-like lock:





I'm pretty sure this is the design I'll go for. I then found a small piece of 1/4" Amsteel that I tried out but it was a couple of inches too short; I just made a real small shackle out of it to get an idea of what 8,600lb breaking strength looks like. The total diameter of the splice is 1/2" or 12mm. I may have one shackle on my main boom and 4 or so on my runners that this can replace. Here is a picture with all three:


The diamond knot is not easy. Creating it is one but then tightening it is another skill. But when you're handy with ropework this is very much doable and you save plenty money because these shackles go for between $24 - $30 or so while they only have 3-4' of rope each, plus a cent for twine.

By the time I'm done, I'll be probably so quick making them that I should start selling them

ciao!
Nick.
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Old 29-04-2013, 00:23   #2
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Re: More work: soft shackles

Nice work! They are a thing of great beauty. I would love to get one on a test bed and see what they can really take. Looking forward to your in use tests. Thanks for sharing.
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Old 29-04-2013, 06:11   #3
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Nice work! They are a thing of great beauty. I would love to get one on a test bed and see what they can really take. Looking forward to your in use tests. Thanks for sharing.
Thanks. Even though some individual ones test better than others, most come out at less than 125% of line strength. You have to be very carefull about that line used: many specify the thickness of the shackle, like 3/8" instead of the line used to make the shackle, which is 1/4" in that case. The strength is just equal to 1/4" rope, not 3/8". It is the diamond knot that fails in destructive testing.

The rope used is so strong that they easily outperform stainless and never have haircrack problems. When they wear out you get plenty visual indication wellbefore that. My 8 year old Amsteel runners are still good but I plan to replace and test them at 10 years to get a feel on how they age.
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Old 29-04-2013, 06:30   #4
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Re: More work: soft shackles

These look really good. A friend who crewed on our last Hawaii trip uses these on his boat. He gave me a few he had made, plus a kit he had put together so I can make my own.

One thing I might be careful about is using the soft shackle on a metal fitting (eye) with squared edges. I've got some fittings like this on my boom where I currently use stainless shackles, and I'm concerned that the edges might stress or cut the soft shackles.
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Old 29-04-2013, 06:34   #5
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Re: More work: soft shackles

What would be the strength of the soft shackle without a thimble?

When you are calculating your cost savings did you consider the cost of thimbles to conserve the bending radius and hence the strength of the line.

Thimble
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Old 29-04-2013, 06:51   #6
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Re: More work: soft shackles

Nick,

This is great stuff.... I'm slowly becoming a die hard convert.... I've been researching a lot of synthetic, as I am contemplating using it for a full/partial rig... These shackles show up a lot.... The advantages are so overwhelming.... I hope to remove 50 lbs out of my "shackle drawer" soon!

Thanks for POSTING!!!
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Old 29-04-2013, 06:56   #7
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Re: More work: soft shackles

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Originally Posted by KrazySailing View Post
What would be the strength of the soft shackle without a thimble?

When you are calculating your cost savings did you consider the cost of thimbles to conserve the bending radius and hence the strength of the line.

Thimble
There are no thimbles. The strengths stated are without using thimbles.

The tightest bends possible with the rope are made within the diamond knot. That is why the shackle is only at 25% of it's potential strength, this factor is already accounted for

Nobody came up with an improvement on the stopper knot yet. But they did come up with the loops that just have a splice. The splices do much better in tests when they are tapered good enough. It's okay to start thinking about them as maintaining 100% line strength when you make them 3 fids long with a 1 fid taper length. My 10mm fid is 9" long so a splice would be 27" long for full strength.
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Old 29-04-2013, 07:03   #8
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Re: More work: soft shackles

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Originally Posted by Paul Elliott View Post
These look really good. A friend who crewed on our last Hawaii trip uses these on his boat. He gave me a few he had made, plus a kit he had put together so I can make my own.

One thing I might be careful about is using the soft shackle on a metal fitting (eye) with squared edges. I've got some fittings like this on my boom where I currently use stainless shackles, and I'm concerned that the edges might stress or cut the soft shackles.
You will be surprised how chafe resistant Dyneema is. Being slippery is the negative that comes with that. When cycling loads are constant then yes, it will be bad, but often just oversizing will take care of it again. When you buy these at $28 each, it would get tiring to try and replace all the time but being retired and all, one can put some time in to make more and experiment

You also have to convert and get used to the new concept. For example, you need to remove those fitting from your boom and just put them out of your mind. Instead, you use Dyneema around the boom. Maybe a small padeye to keep the Dyneema from sliding away. Now it is much stronger and you got rid of even more metal that can have hair cracks, crevice corrosion, needs polishing etc.
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Old 29-04-2013, 07:12   #9
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Re: More work: soft shackles

How are you attaching these to your halyards? are you just sliding them through an eye splice? Thanks
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Old 29-04-2013, 07:14   #10
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Re: More work: soft shackles

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Originally Posted by HappyMdRSailor View Post
Nick,

This is great stuff.... I'm slowly becoming a die hard convert.... I've been researching a lot of synthetic, as I am contemplating using it for a full/partial rig... These shackles show up a lot.... The advantages are so overwhelming.... I hope to remove 50 lbs out of my "shackle drawer" soon!

Thanks for POSTING!!!
I replaced my lifelines with Spectra in 2003. Everybody told me I was crazy, but look how different that is today. Everybody is installing rope lifelines (back to the old days) and I should replace them already

The rig: for bigger boats and for fractional rigs I still see many disadvantages that have to do with either creep or very big diameter Dynex Dux. I may go for rod rigging next time I replace my standing rig. But even then, there is so much steel that can be replaced besides the rigging.

My Dyneema lifelines and runners are some of the best upgrades we did. I'm less happy with the Vectran halyards and will use Dyneema next time. Vectran does not do so well under the tropical sun and I don't like the feel of the material that well.
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Old 29-04-2013, 07:26   #11
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Re: More work: soft shackles

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How are you attaching these to your halyards? are you just sliding them through an eye splice? Thanks
For polyester halyards, you need to splice an eye with thimble in them, after which you can use a soft shackle to attach it to the sail.

For high tech rope halyards like Dyneema and Vectran, you can splice an eye without thimble and use a soft shackle of the same rope. When you switch from polyester halyards, you might need new rope clutches (I did) because the new ones are much thinner. You also need them to be thinner because the splice is much longer and needs to go over the masthead sheave.

Example: Staset-X 7/16" halyards are popular at 7,400lb breaking strength. When you replace that with 1/4" Amsteel, you get stronger halyards at 8,600lb breaking strength but will need new rope clutches. For Spinlock (the best for high tech rope IMHO) you might be able to get new cams. I am replacing Lewmar with Spinlock.

I have Vectran halyards with the Wichard shackles that are designed for those with the blue plastic thimble integrated with the shackle. I even have spares for those expensive beasts... time to sell them
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Old 29-04-2013, 07:35   #12
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Re: More work: soft shackles

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Originally Posted by s/v Jedi View Post
I replaced my lifelines with Spectra in 2003. Everybody told me I was crazy, but look how different that is today. Everybody is installing rope lifelines (back to the old days) and I should replace them already

The rig: for bigger boats and for fractional rigs I still see many disadvantages that have to do with either creep or very big diameter Dynex Dux. I may go for rod rigging next time I replace my standing rig. But even then, there is so much steel that can be replaced besides the rigging.

My Dyneema lifelines and runners are some of the best upgrades we did. I'm less happy with the Vectran halyards and will use Dyneema next time. Vectran does not do so well under the tropical sun and I don't like the feel of the material that well.

Lifeline convert is a no brainer.... On the very short to do list! Plus it looks fantastic....

Large boat size and rig is indeed my hurdle and stumbling block for the changeover/conversion.... If it were the smaller boat, I would do it in a heartbeat.... I think there is going to be a good compromise IF.... I can handle the look and aesthetics of a mix... Not sure...

Many thanks on the halyard recommendation.... These will be done with the rig too....
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Old 07-05-2014, 11:16   #13
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Re: More work: soft shackles

Jedi:

Thanks for the photo's. Learning to make some soft shackles is on my list of things to do. As well as replacing the lifelines. Just bought some Tenex Tec line to play around with too.
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Old 07-05-2014, 11:54   #14
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Re: More work: soft shackles

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Nobody came up with an improvement on the stopper knot yet.
Both Evans and Brion Toss have developed improved stopper knot designs that significantly improve the soft shackle strength.
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Old 07-05-2014, 15:28   #15
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Re: More work: soft shackles

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Both Evans and Brion Toss have developed improved stopper knot designs that significantly improve the soft shackle strength.
How about some links?
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