Unveiling the BB Soft Shackle

[estarzinger]

Originally Posted by Seaworthy Lass

Improving the strength of the loop is another matter .

Brion did make and I tested a couple versions with stronger noose - we essentially inserted extra dyneema inside there (in a couple different ways). They did increase the strength again - to the point that I could not break 6mm shackles at all with my test rig - scary high loads. BUT - all the versions we tried were stiffer to work, and used so much dyneema between the tail buries and the extra in the loop that you might as well have just used thicker dyneema to start with.

[Stumble]

Estar,

for snubbers I doubt shock loads are an issue. The nylon line should provide plenty of spring. But if you want some elasticity in the shackle itself what about making them out of Tenex. It's a high strength hollow core polyester line that I use for bulking covers over amsteel.

[Panope]

Re: Using a soft shackle to connect snubber to chain-

If ultimate strength of the soft shackle is in doubt, why not use a very long soft shackle and make two (or three) loops through two (or three) links of chain?

I realize that the extra one (or two) of these loops will be wedged/pinched by the chain but it would seem that the doubling (or tripling) of the strength would more than make up for this (theoretical) problem.

Steve

[Seaworthy Lass]

Originally Posted by Panope

Re: Using a soft shackle to connect snubber to chain-

If ultimate strength of the soft shackle is in doubt, why not use a very long soft shackle and make two (or three) loops through two (or three) links of chain?

I realize that the extra one (or two) of these loops will be wedged/pinched by the chain but it would seem that the doubling (or tripling) of the strength would more than make up for this (theoretical) problem.

Steve

I think it would be impossible to achieve an even load distribution with the tension being load and unloaded, particularly if any portion of the shackle was being pinched between the chain links.

Also, one big advantage of using a soft shackle is ease of use. I think pushing it through more than one link of chain would negate this.

SWL

[estarzinger]

Originally Posted by Stumble

Estar,

for snubbers I doubt shock loads are an issue. The nylon line should provide plenty of spring. But if you want some elasticity in the shackle itself what about making them out of Tenex. It's a high strength hollow core polyester line that I use for bulking covers over amsteel.

I agree - there should be no problem with the dyneema shackle in a system with a decent length of nylon.

I'v made a couple from both 5/16 Tenex and Regatta Braid - they make nice shackles that are in fact plenty strong enough for most applications. Because the polyester is less slippery, the knots are a bit harder to pre-tension, but there is also almost zero risk the tails will suck into the knot. Also, relatively speaking, they were a bit stronger vs their breaking strength than dyneema, because the knot does not weaken polyester as much as it does dyneema. I had them hanging from my harness and used them when working up the mast for various temporary purposes.

But these would be too big to push thru 10mm chain. and I'd have to think about it but don't think off the top of my head that 1/4" polyester would be 'strong enough'.

On further reflection - I think that when I figured I needed a 'stronger' soft shackle, I was factoring in the possibility of several types of strength losses - possible 50% loss due to UV, possible 15-20% loss due to rope batch and shackle construction imperfections, possible 15-20% due to chafe . . . and just figured that an extra 30-50% of better design could certainly not hurt.

[jcapo]

Originally Posted by Panope

Re: Using a soft shackle to connect snubber to chain-

If ultimate strength of the soft shackle is in doubt, why not use a very long soft shackle and make two (or three) loops through two (or three) links of chain?

Most of the time I use a long "better" soft shackle made from 1/4" line attached to the chain with a prusik knot or a cow hitch. What little wear there is on the shackle is spread over a larger area. A shackle made from 1/4" line won't fit through my 5/16 HT chain.

[jcapo]

A few months ago I made what you are calling the BB shackle. I couldn't find a way with what I have available to tension the knot to my satisfaction. I went back to the Allen's better version.

[Seaworthy Lass]

Originally Posted by jcapo

Most of the time I use a long "better" soft shackle made from 1/4" line attached to the chain with a prusik knot or a cow hitch. What little wear there is on the shackle is spread over a larger area. A shackle made from 1/4" line won't fit through my 5/16 HT chain.

A Klemheist hitch is excellent if the pull is in one direction and it is quicker to tie compared to a Prusik hitch. Has a Cow hitch ever jammed? Or have either slipped with the slippery Dyneema when load is constantly applied and released, as it is here? In calmer conditions the connection will often be lying on the seabed.

I would personally prefer to use a double braided dacron Prusik loop in this application (the best solution in my opinion if you are not using a soft shackle through the chain links).

Originally Posted by jcapo

A few months ago I made what you are calling the BB shackle. I couldn't find a way with what I have available to tension the knot to my satisfaction. I went back to the Allen's better version.

I have been tensioning the Button exactly as I do a Diamond (tightened with a marlin spike initially then fed through a washer on a vice and pulled), except after pulling on the two standing ends using a rod inserted through the loop, I then tug the working ends one by one, then I repeat once. Evans may have a better suggestion for the Button.

The soft shackles from last year that have been used on the snubber were not tightened as well with a Marlin spike and they slid about a cm on the vice. They have not appeared to have shifted any more than a couple of mm while in use.

This year when I made a few Better shackles (mainly in 5mm for general use), I tightened up very carefully pulling as hard as I could on the marlin spike on each bit as I worked around. The rock hard knots barely shifted in the vice at all then. The same applies with the Buttons I have made this week.

I will put a tiny marker on the first BB we use on the snubber to enable me to then check how much the Button shifts with use.

What problems have you had with tightening?

SWL

[jcapo]

Has a Cow hitch ever jammed?

I only use the cow hitch for short periods at anchor with little chance of big winds so I don't know if it will jam or not.

Or have either slipped with the slippery Dyneema when load is constantly applied and released, as it is here? In calmer conditions the connection will often be lying on the seabed.

I have used the prusik in 25+ northwest winds in the Bahamas with miles of open fetch. Not fun. Last winter I went through many cold front passages in Florida with 20 knot winds for a day or two and then calm for days. No slippage.

What problems have you had with tightening?

I can tighten the button by hand but nowhere near the 1000lbs I apply to the better or conventional shackle using cockpit winches. I am going to tinker with the BB some more.

[estarzinger]

I think you will always be able to open a cow hitch, at least with a spike.

As to tightening - I found the best procedure was to get it reasonably firm in one of the many ways by hand - SL's washer approach is a good one but there are others - but then the real key is to really load it - I use by test rig hydraulic rams ashore and my biggest genoa winches on the boat - with the winches I just crank on as much load as I possibly can (which is about 5000lbs) and let it sit on the shackle for 20 minutes. That truly sets the knot. On bigger diameter shackles (6mm stronger design and bigger) I use the biggest winches + a 2:1 tackle to get enough load. You actually strengthen the dyneema by stressing it.

I will note that while some people think they can tell - I believe that no-one can tell by feel a 'somewhat set' stopper from a 'properly set' one. The 'somewhat set' ones can feel like rocks, but still have a lot left to take up when you really load them. As I mentioned I have had ones made by both Brion and Allen which when tested were actually only 'somewhat' set - have been able to pull 2cm of line out of them when 'properly set'.

[Seaworthy Lass]

Originally Posted by estarzinger

As to tightening - I found the best procedure was to get it reasonably firm in one of the many ways by hand - SL's washer approach is a good one but there are others - but then the real key is to really load it - I use by test rig hydraulic rams ashore and my biggest genoa winches on the boat - with the winches I just crank on as much load as I possibly can (which is about 5000lbs) and let it sit on the shackle for 20 minutes. That truly sets the knot. On bigger diameter shackles (6mm stronger design and bigger) I use the biggest winches + a 2:1 tackle to get enough load. You actually strengthen the dyneema by stressing it.

I will note that while some people think they can tell - I believe that no-one can tell by feel a 'somewhat set' stopper from a 'properly set' one. The 'somewhat set' ones can feel like rocks, but still have a lot left to take up when you really load them. As I mentioned I have had ones made by both Brion and Allen which when tested were actually only 'somewhat' set - have been able to pull 2cm of line out of them when 'properly set'.

I will set with a winch for the next shackle I make . I have one final bit of Amsteel Blue so I will try this in the next few days.

The initial soft shackles I made last year without firstly super tightening using a marlin spike shifted about a cm in the vice, then only a small amount on the snubber (definitely less than half a cm). The ones this year where I used every bit of my puny strength to tighten with with the marlin spike have barely moved in the vice.

I made up a BB soft shackle in 6mm Amsteel Blue and this was deployed on its maiden trial today. I thought it would be interesting to see how much the Button shifts with use, so I added a tiny bit of line as a marker. I have just come back from a swim after photographing it. When I warm up I will post a few photos.

I left off the lock near the button end of the central bury of this one. Looking at it, I can't really see the need for the one at the other end of the bury either. The next shackle I will leave both off unless you advise otherwise. I think it will help the load on the central buried portion distribute more evenly between the inner and outer parts and it saves a couple of insertions .

SWL

[weavis]

what the frap?!

I spent hours following your instructions........

[estarzinger]

Originally Posted by Seaworthy Lass

The next shackle I will leave both off unless you advise otherwise. I think it will help the load on the central buried portion distribute more evenly between the inner and outer parts and it saves a couple of insertions .

SWL

My experience with the 'importance' of 'extra tightening' the stopper comes from breaking a lot of them on the test bench - probably in 'normal use' it is not as noticeable since you are likely only getting to half breaking strength max. So, my perspective on that is probably a bit artificially skewed.

I think the fewer 'locks' you have in the design the better - but I did not test all the variations - so can't guarantee anything

[Seaworthy Lass]

Originally Posted by weavis

what the frap?!

I spent hours following your instructions........

That looks better than my first attempt (see the "What's the latest" thread ).
By the way, did you know that the inspiration for the Button apparently came after placing some line in a spare locker and retrieving it after 30 days?

SWL

[Seaworthy Lass]

The photo shoot before the launch of the BB soft shackle:







Note that unlike the Better, there is no lock at the end of the central bury at the Button end. The next one will be without the lock at the loop end of the central bury as well: