Soft Shackle for Bridle Attachment?

[LagunaRed]

Hi Everyone,

We're working on figuring out the simplest way to attach the bridle to the chain on our Lagoon 52 catamaran. We found this heavy duty spectra soft shackle that's really easy to attach and we were told it's break strength is 30 tons (60,000 pounds). I'm not sure I believe that but I couldn't find anything to support the claim either way. My question is whether any of you use a soft shackle for this purpose and what your thoughts on using this method in general. Thanks in advance for any advice.

[Cotemar]

Soft Shackles on and anchor bridle

The breaking strength of these Amsteel / Dyneema 12-strand Soft Shackles is equal to their advertised tensile strength.

Strong as steel yet floats on water.

1/8", (.125) is 2,500 lbs .250 finish dia.
5/32", (.156) is 4,000 lbs .300 finish dia.
3/16", (.187) is 5,400 lbs .340 finish dia.
1/4", (.250) is 8,600 lbs .450 finish dia.
5/16", (.312) is 13,700 lbs .550 finish dia.
3/8", (.375) is 19,600 lbs
7/16", (.437) is 23,900 lbs
1/2", (.500) is 34,000 lbs
5/8", (.625) is 40,700 lbs

You have to make sure to pick the Largest Soft Shackle that will fit through your anchor chain.

I made Soft Shackles for a few Nordhavn 72 footers that have been using them for anchoring for a few years now.

[Seaworthy Lass]

Originally Posted by LagunaRed

Hi Everyone,

We're working on figuring out the simplest way to attach the bridle to the chain on our Lagoon 52 catamaran. We found this heavy duty spectra soft shackle that's really easy to attach and we were told it's break strength is 30 tons (60,000 pounds). I'm not sure I believe that but I couldn't find anything to support the claim either way. My question is whether any of you use a soft shackle for this purpose and what your thoughts on using this method in general. Thanks in advance for any advice.

We have successfully used a soft shackle between our snubber and chain for several years now.

The breaking strength you have been quoted sounds wrong though. I think soft shackles having this breaking strength would be too thick to go through chain you are likely to be using.

SWL

[UNCIVILIZED]

It's quite common to use a soft shackle in lieu of a chain hook on bridles & snubbers. Especially as they can't/don't fall off. And of course the strength's great, albeit dependent on the grade of Spectra used. With higher grades of Spectra resulting in stronger soft shackles, though even using the lower grades, the soft shackles will likely be stronger than your chain or rope rode.

[Stumble]

You didn't give a size of dyneema, but 30k lbs doesn't sound all that hard to believe. As mentioned above a standard soft shackle has a MBL around the strength of the line it is made from, high efficiency ones can have a strength >150% the strength of the line.

The recommendation for using the largest possible soft shackle isn't just the strength, you normally wouldn't need close to that on a bridle, but also because the larger it is the more tolerant of abrasion. And frankly because they are so cheap to make.

[Seaworthy Lass]

Originally Posted by UNCIVILIZED

It's quite common to use a soft shackle in lieu of a chain hook on bridles & snubbers. Especially as they can't/don't fall off. And of course the strength's great, albeit dependent on the grade of Spectra used. With higher grades of Spectra resulting in stronger soft shackles, though even using the lower grades, the soft shackles will likely be stronger than your chain or rope rode.

Commercially available soft shackles made with SK75 that are tied with a diamond stopper may have only about 70% the breaking strain of the G4 chain they will fit through, depending how the shackles are made.

Cotemar's images show shackles made using a diamond stopper. The one on the left is the "better" version, but this only relates to ease of opening, not strength. Well made ones using a diamond stopper have a breaking strain of around 175% of the dyneema used. Some figures are around 135%.

Using a Button stopper this will rise to around 230%, but I have never seen this available commercially.

The breaking strain of the snubber is the more important factor though, not the chain.

[Seaworthy Lass]

Originally Posted by Stumble

You didn't give a size of dyneema, but 30k lbs doesn't sound all that hard to believe. As mentioned above a standard soft shackle has a MBL around the strength of the line it is made from, high efficiency ones can have a strength >150% the strength of the line.

The recommendation for using the largest possible soft shackle isn't just the strength, you normally wouldn't need close to that on a bridle, but also because the larger it is the more tolerant of abrasion. And frankly because they are so cheap to make.

Hi Greg
The figure that was quoted in post #1 was 60,000 lbs, not 30K.

Even 30,000 lbs seems way too high though.

eg 10 mm G4 chain has a breaking strain of around 16200 lbs.
The largest soft shackle that will fit through is made of 6mm dyneema. The strength of the soft shackle will depend on the exact dyneema used, the style of shackle and how well it is made, but 6mm SK75 itself has a breaking strain of only around 9300 lbs.

SWL

Edited to add:
Figures get a bit closer for 12mm chain and soft shackles using 8mm dyneema:
12 mm G4: 21600 lb breaking strain
8 mm SK75: 14800 lb breaking strain
A well made "high strength" soft shackle using 8 mm SK75 (not one using a diamond stopper) may have a breaking strain of around 34,000 lb.
Still half the quoted figure of 60,000 lb though.

[Tkeeth]

The ones I make are the "better" ones, learned it on youtube. I am using them everywhere. I hate getting whacked with metal shackles.

[Stumble]

Originally Posted by Seaworthy Lass

Hi Greg
The figure that was quoted in post #1 was 60,000 lbs, not 30K.

Even 30,000 lbs seems way too high though.

eg 10 mm G4 chain has a breaking strain of around 16200 lbs.
The largest soft shackle that will fit through is made of 6mm dyneema. The strength of the soft shackle will depend on the exact dyneema used, the style of shackle and how well it is made, but 6mm SK75 itself has a breaking strain of only around 9300 lbs.

SWL

Edited to add:
Figures get a bit closer for 12mm chain and soft shackles using 8mm dyneema:
12 mm G4: 21600 lb breaking strain
8 mm SK75: 14800 lb breaking strain
A well made "high strength" soft shackle using 8 mm SK75 (not one using a diamond stopper) may have a breaking strain of around 34,000 lb.
Still half the quoted figure of 60,000 lb though.

Wow, I completely missed that. I read 30 ton stuff as 30k lbs...

But where would you even go to buy SK-75 anymore? Most of the entry level dyneema these days is so-78 (Amsteel blue, etc.). To build a soft shackle with a 60k MBL on a conservative 150% shackle would require 14mm (9/16) sk-78. Not particularly massive.

But I agree that with any reasonable line size the weak point is going to be the bridle line not the shackle anyway. Ideally sized as a fuse below the breaking strength of the cleat.

[Seaworthy Lass]

Originally Posted by Stumble

Wow, I completely missed that. I read 30 ton stuff as 30k lbs...

But where would you even go to buy SK-75 anymore? Most of the entry level dyneema these days is so-78 (Amsteel blue, etc.). To build a soft shackle with a 60k MBL on a conservative 150% shackle would require 14mm (9/16) sk-78. Not particularly massive.

But I agree that with any reasonable line size the weak point is going to be the bridle line not the shackle anyway. Ideally sized as a fuse below the breaking strength of the cleat.

SK75 is still commonly available I think (Amsteel Blue is SK75). It was released around the same time as SK78. The difference in strength between them is negligible, but SK78 has less creep.

PS I have never attempted making a soft shackle from 14mm dyneema, but it would be super chunky from my point of view . I can't see how it could be used on chain a 52' cat would typically be using.

[Tkeeth]

Originally Posted by Seaworthy Lass

SK75 is still commonly available I think (Amsteel Blue is SK75). It was released around the same time as SK78. The difference in strength between them is negligible, but SK78 has less creep.

PS I have never attempted making a soft shackle from 14mm dyneema, but it would be super chunky from my point of view . I can't see how it could be used on chain a 52' cat would typically be using.

https://www.amazon.com/Amsteel-Blue-...ywords=amsteel

There is a chart on this listing, 60K lbs. is possible above 1/2 inch sizes.

[Seaworthy Lass]

Originally Posted by Seaworthy Lass

SK75 is still commonly available I think (Amsteel Blue is SK75). It was released around the same time as SK78. The difference in strength between them is negligible, but SK78 has less creep.

I went to check this out. My mistake.
Amsteel Blue is available as both. I have only seen SK75 sold. Westmarine is selling AmSteel-Blue Dyneema® AS-78.

[Paul L]

I've used a soft shackle on our snubber for at least 3 years. I did have one incident where a fairly new 5/8" snubber snapped, with no apparent damge to the soft shackle.

If you are using a large diameter shackle relative to the chain, I add a whipping thread leader to the loop of the shackle. It makes it simpler to pull it through the chain opening.

[Cotemar]

Here's the Soft Shackle that the big Yachts, Ships and Tugs use.

[Hoofsmit]

Good to hear the testament of you guys/ girls who have been using them for years, I always thought that these high strength Dyneemas were susceptible to abrasion