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Old 22-11-2013, 05:18   #1
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So how Strong are Soft Shackles?

Here's a pic of a soft shackle holding a 5/8" Brait (8-plait) snubber. The snubber snapped, but the soft shackle on the boat side and the chain side held with no signs of damage. The shackles were made out of 1/4" spectra. The breaking load on the Brait is listed as 12,000lbs. I'm still not sure what caused the snubber to snap. It was during backing down on the anchor in fairly mild conditions. The line was about 5 months old and doesn't show any significant chafe, other than the fuzz that Brait gets.
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Old 22-11-2013, 05:49   #2
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Re: So how strong are soft shackles?

I use a lot of Soft Shackles now. It’s just amazing how strong they are.
Here are the strengths for the different Soft Shackle sizes.

A 3/16 Amsteel Soft Shackle fits through a 5/16 High Tensile G4 chain link

1/8" is 2,500 lbs
5/32" is 4,000 lbs
3/16" is 5,400 lbs
1/4" is 8,600 lbs
5/16" is 13,700 lbs
3/8" is 19,600 lbs
7/16" is 23,900 lbs
1/2" is 34,000 lbs
5/8" is 40,700 lbs
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Old 22-11-2013, 07:38   #3
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Re: So how strong are soft shackles?

I suspect it is more of a case that that snubber was severely compromised rather than the shackle was stronger than expected.

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Old 22-11-2013, 08:24   #4
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Re: So how strong are soft shackles?

Soft shackles are slightly stronger than the line they are made from.

Soft Shackle Testing Part 3
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Old 22-11-2013, 09:00   #5
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Re: So how strong are soft shackles?

Where exactly was the break? Estarzinger talked about line breakage too, his broke nowhere near any chafe points, bends, or splices. Or am I remembering wrong?
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Old 22-11-2013, 09:04   #6
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Re: So how strong are soft shackles?

Another possibility is that there was slack in the anchor rode and the backing impact was significant; because of the unusual way this snubber is secured, I think this is likely. Assuming the boat was backing at 4 knots, weighed 28,000 pounds, and was snubbed in 3 feet (lets say 0.1 G max) the impact would be ~ 2800 pounds. Not a worrisome amount and what 5/8" brait is sized for, when the boat is horsing around in waves.

How many anchoring days on the snubber, do you remember?
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Old 22-11-2013, 09:30   #7
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Re: So how strong are soft shackles?

Interesting...

I have no idea if this is relevant, but in a great many years of anchoring, the only snubber that I have ever had fail was also brait construction. In our case, the chain was fouled and the boat pitching a bit, but I was quite surprised that it broke. Perhaps the brait construction is a poor choice for this application... I dunno. We have used both 3-strand and double braid nylon of various sizes for thousands of nights anchoring with the occasional bit of chafe but no failures (so far).

Any thoughts?

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Old 24-11-2013, 01:10   #8
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Re: So how strong are soft shackles?

Quote:
Originally Posted by thinwater View Post
Another possibility is that there was slack in the anchor rode and the backing impact was significant; because of the unusual way this snubber is secured, I think this is likely. Assuming the boat was backing at 4 knots, weighed 28,000 pounds, and was snubbed in 3 feet (lets say 0.1 G max) the impact would be ~ 2800 pounds. Not a worrisome amount and what 5/8" brait is sized for, when the boat is horsing around in waves.

How many anchoring days on the snubber, do you remember?
Backing at 4 knots? That is fast! I'm not doubting it, nor believing it - just interested in how the figure was derived. To accelerate a yacht, any yacht, to 4 knots takes a lot of space (and the engine at flat chat). Wind pushing yacht backwards, or sideways?

I do not know - so am interested in a decent comment.

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Old 24-11-2013, 09:59   #9
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Re: So how strong are soft shackles?

We were just starting backing down and there was maybe an 8in chop that did bounce us a little. The backing speed was negligible. The brait broke about 18-24 in from the end of the splice. The line was about 4-5months old with maybe 90-110 days of anchoring on it. It has the fuzz that brait gets for a few feet either side of the break, but it does not look chafed at all. I really can't figure why this thing snapped. It was Yale Brait bought from Defender.
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Old 24-11-2013, 11:02   #10
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Re: So how strong are soft shackles?

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Backing at 4 knots? That is fast! I'm not doubting it, nor believing it - just interested in how the figure was derived. To accelerate a yacht, any yacht, to 4 knots takes a lot of space (and the engine at flat chat). Wind pushing yacht backwards, or sideways?

I do not know - so am interested in a decent comment.

Jonathan
In some ways, just a crazy worst-case number to do a calculation. However, the line did break and I don't think it is a completely crazy number, for 2 reasons:
  • Because the snubber anchor is on the stem the operator would not be encouraged to maintain tension, as for example, a chain hook would require. Thus, while fiddling with soft shackle in light winds, it is possible the boat could have moved forward on the chain and then been backed a bit fast. No, not probable.
  • It is possible that the boat had seen a 4-knot surge at some time in the past, knocked around by waves. In other words, could the damage have been per-existing?
My point was that either way, the calculation showed that the line was appropriate in size, leaving us with a mystery. Nothing more.

100 days use, it sounds like most often in relatively benign conditions. That does not strike me as old,

Brait wrong for the application? Interesting. Common for that boat for dock line or anchor rode, though snubber is a little different. In fact, many folks would use 1/2" for a snubber, though at 100 days they would expect wear (typically a 1/2" snubber would be longer).

How long was the snubber? They really cannot absorb impact unless long enough.
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Old 24-11-2013, 11:23   #11
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Re: So how strong are soft shackles?

The snubber was 25 feet before the spliced, so say 20-22 feet. The anchoring time on the snubber was mostly benign with a few days of 20+ thrown in. One reason I went with the soft shackles was because they take less fussing to set on the chain than a rolling hitch or my dual chain hook. They don't get hung up on the roller stem either.
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Old 24-11-2013, 12:09   #12
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Re: So how strong are soft shackles?

My guess is that either you just got a bad piece of line (which does happen from time to time), or you had a bad splice. Brait is a pretty tricky line to splice well because of the number of legs that have to be worked with. If the taper isn't done properly it can create stress risers typically at the end of the splice, which will quickly snap the line.

Brait is a pretty well proven shock absorbing line, used for years in the commercial industry as dock lines before the recreational side picked it up as anchor line.


As for the original question... If they are done properly a soft shackle is typically rated as the same strength as the line it is made from. With the break point being right at where the line enters the diamond knot.
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Old 24-11-2013, 12:27   #13
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Re: So how strong are soft shackles?

I'm amazed it broke actually... dont really care if the boat was doing 6 knots... It truly may speak of plait not being a good thing... what else coud it be? geez.. I have used 1/2 and 5/8 3 strand for snubbers on boats up to 47 feet and 40k lbs... seen them bar tight after a couple years use with no issues.... gotta be a defect..which is not encouraging from a name brand....
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Old 24-11-2013, 17:10   #14
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Re: So how strong are soft shackles?

I guess it could be related to the splice - hell, I'm the one that did the splice and they never turn out that pretty- , but it did break at least 18 inches away from the end of the taper of the the splice. Perhaps the strands were pulled up unevenly and it affected the line aways from the splice?????
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Old 24-11-2013, 17:48   #15
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Re: So how strong are soft shackles?

We have always used 5/8" octoplait for bridle lines, and I am very surprised to hear of this breakage. We usually go 5 years on them, at which time they are stiff, barnacle encrusted and have lost stretch. They regularly see lots more force than you describe, yet we have never broke one.

The only difference is we have always used Buccaneer Rope plait, and not Yale Brait. I just made up a new bridle with one leg Buccaneer and the other leg Yale (they were a good price in the cutoff bin). It will be interesting to see if one leg breaks!

BTW, our plait bridles never get fuzzy like yours show. Neither does the rope rode backing up our anchor chain, although that doesn't get deployed as much. That fuzz is curious. You see that regularly?

I don't find plait splices any trickier than 3-strand and the taper is done exactly the same - just remove half the strands and make a couple more tucks.

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