Break Test Extravaganza(s)

[k7cej]

Brion:
I have been away from SparTalk for a while and find the soft shackle thread intriguing. I would like to make some but am somewhat confused as to which design to use. So far, the immediate links lead to three different designs.

On our Outbound 44 Sequoia we use quite a few Spectra web loops (5/8" sewn loops purchased from REI) to attach blocks to the Al toe rail or foredeck padeyes. typically, we pass a bight through the attachment and capture both "ends" of the doubled loop in the block's shackle. (There are thus 4 lengths of web sharing the load.) This eliminated metal-metal wear and noise, and I have never had one wear out or break in >33,000nm.

So if I want to make soft shackles with the strength of 3/8" 316 stainless shackles, which design and what line size would you recommend?
Craig

[Brion Toss]

Hi there,
Depending on the alloy, that 3/8" pin shackle might have a breaking strength as high as 13,000lbs. With the "conventional" form of soft shackle, you could use 1/4" in regular Spectra -- just -- but it would be safer to use 5/16". With my version, 1/4" would be generous. Most steel shackles of that diameter have breaks closer to 9,000lbs.
Fair leads,
Brion Toss

[allene]

I made up four samples and will send them in. One is my standard better soft shackle and two are similar with variations on the knot. The fourth one is the stronger soft shackle.

Allen

[k7cej]

I have made up two using AmSteel-Blue AS-78, 1/4" diameter, using the button knot with the ends tucked back through and buried.
1. I found it much easier to tie the button knot if I marked one side with black sharpie.
2. Boating friends were impressed, but asked a good question: "If you used one to connect genoa sheets to the sail, how secure would it be when the sail was flogging?" Does anyone have real world experience?
3. Has anyone used this to replace a main halyard shackle?

[benz]

I use soft shackles all over my boat, and have never had one flog itself loose. I'd say if the eye that chokes down after passing over the knot is small enough, threre's little-to-no chance of flogging loose. I've also never had a toggle shackle flog loose, and those seem a little less secure. All my halyards have soft attachments.

[allene]

Originally Posted by k7cej

I have made up two using AmSteel-Blue AS-78, 1/4" diameter, using the button knot with the ends tucked back through and buried.
1. I found it much easier to tie the button knot if I marked one side with black sharpie.
2. Boating friends were impressed, but asked a good question: "If you used one to connect genoa sheets to the sail, how secure would it be when the sail was flogging?" Does anyone have real world experience?
3. Has anyone used this to replace a main halyard shackle?

1) I agree
2) I use my "improved soft shackle" and find them quite secure. I have used them on my larger jibs for several years and never an issue. They tend to close under load, not open.
3) I use a soft shackle as part of the "hybrid soft halyard shackle" you can read about here http://L-36.com/HybridHalyard.php. I would not use one on a jib halyard as they do take more time to put on and off but on a main they work really nice.

[Brion Toss]

Hello all,
Thanks to those who have sent in pieces to break. We are getting ready to send them on to Treestuff, so if you have been planning to participate, it is time to get in gear. And it isn't just for soft shackles, so if you have any sort of experimental rope structure to test, there is room.
Fair leads,
Brion Toss

[MarkG]

Thew were sent priority mail today and should be there by Monday.

Mark