Splicing loops in Amsteel question and Improved Soft Shackle

[tobiusnc]

Hello All,

I'm fairly new, but I've been doing a lot of reading, thinking and tinkering with my suspension. I think I'm close to having something I'm happy with, but I'm looking for a solution to my final problem. I won't go into a long description of my suspension here, but for context, it's essentially a double whoopie sling SLS using 1/8 Amsteel. I currently have descender rings on the SLS allowing me to adjust the hang position, and I attach/detach the hammock using soft shackles (see below). I would like to replace these with a loop in the SLS once I dial in the ridge line length I like. I've tried alpine butterfly loops, but as has been said around the forum many times, Amsteel isn't meant to be knotted, and even something like the butterfly derates the rope to under 40%. Likely still plenty strong, but in my experimenting I've seen how much abuse it puts on the rope and I don't love it.

Since Amsteel lends itself to splicing, I'm trying to find a way to splice a loop into the main line. I have a few ideas but they all have the problem of exiting the main at an angle, which I think will cause a problem. Is there any splice technique that will allow this to work without damaging the main line? I think is my best idea at the moment is to create a fixed eye then tie the tail to the main line using essentially a tautline with the tail buried in the mainline. I'm sure that's confusing, so I'll try to post pictures. Any alternatives to what I'm trying to do? My limited experience indicates Prussik/Kleimholst knots don't hold well on Amsteel, at least with line thick (strong) enough that I'd be comfortable hanging from it.

Soft Shackles:
I found this to make my shackles that I will hang my hammock from. I used a full bury with a release string instead of just the loop, but I really like how the stopper knot is constructed. It's pretty hard to get wrong and seems pretty much bomb-proof. I did a little searching on the forums here and couldn't find a reference to it, so I wanted to share.

http://www.bethandevans.com/pdf/improvedsoftshackle.pdf

[Ridge_Dog]

Not sure if the link works.

[Boston]

Any splice is going to have a big impact on your minimum hang distance, so I'd shy away from that.

I actually did this type of set up when I first got into hammocks. Eventually I realized it doesn't have any advantage over separate suspension and ridge line, and went away from it, and actually has some disadvantages.

However, if you want to keep it, I used alpine butterflies like you were thinking. What I did to avoid problems with the knot was to sheath the line using 550 paracord sheathing (this fit the 7/64 perfectly, and probably will fit the 1/8 [8/64]). I used the inner strings from the paracord to whip the sheathing in place (and prevent freying), then tied the alpine butterflies. I later disassembled this set up and made it into separate whoopie slings and ridge line, and saw no concerns with the amsteel where the knot was. I decided to try this because I read an article somewhere that studied dyneema rope strength with sheathing and a knotted line maintained close to 100% breaking strength of the base rope in that study. The reason is the sheathing increases the bend radius in the knot, which is the primary stress concentrator involved in knots de-rating a rope.

[SilvrSurfr]

That link sounds somewhat unbelievable.

[Boston]

That link sounds somewhat unbelievable.

Why is that?

[juskojj]

i'd trust these people for soft shackles http://l-36.com/soft_shackles.php?menu=4

honestly 1/8 Amsteel is overkill for hanging hammocks, but if it makes you warm and fuzzy, feel free to use it

here's a link directly from amsteel on there size and strengths http://www.samsonrope.com/Pages/Prod...?ProductID=872

edit: here's a word of warning using decender rings and amsteel http://theultimatehang.com/2013/08/h...d-garda-hitch/

[tobiusnc]

Any splice is going to have a big impact on your minimum hang distance, so I'd shy away from that.

I actually did this type of set up when I first got into hammocks. Eventually I realized it doesn't have any advantage over separate suspension and ridge line, and went away from it, and actually has some disadvantages.

However, if you want to keep it, I used alpine butterflies like you were thinking. What I did to avoid problems with the knot was to sheath the line using 550 paracord sheathing (this fit the 7/64 perfectly, and probably will fit the 1/8 [8/64]). I used the inner strings from the paracord to whip the sheathing in place (and prevent freying), then tied the alpine butterflies. I later disassembled this set up and made it into separate whoopie slings and ridge line, and saw no concerns with the amsteel where the knot was. I decided to try this because I read an article somewhere that studied dyneema rope strength with sheathing and a knotted line maintained close to 100% breaking strength of the base rope in that study. The reason is the sheathing increases the bend radius in the knot, which is the primary stress concentrator involved in knots de-rating a rope.

Thanks for the para-cord sheathing suggestion, it's is a really great idea. I remember reading about it a while back, but I had forgotten. That may be where I end up.

I'm not worried about the loop increasing my hang distance, it's already going inside my whoopie splices, and those are inside the length of my tarp ridge-line. Since I don't ever plan to hang without a tarp (at least in the near future), my minimum hang distance is just under 12' plus what the tree huggers add. That puts me at typically about 15', less if I marlin-spike the free end of the hugger.

Here's a picture of what I'm thinking for adding a loop to the main line. The loose end if the fixed eye is wrapped around the main line 3 times, passes back over (similar to taut-line hitch, then buried inside the main line under the loops. Hopefully it's enough to get my idea across.
EyeSpliceSmaller.jpg

[tobiusnc]

i'd trust these people for soft shackles http://l-36.com/soft_shackles.php?menu=4

honestly 1/8 Amsteel is overkill for hanging hammocks, but if it makes you warm and fuzzy, feel free to use it

here's a link directly from amsteel on there size and strengths http://www.samsonrope.com/Pages/Prod...?ProductID=872

edit: here's a word of warning using decender rings and amsteel http://theultimatehang.com/2013/08/h...d-garda-hitch/

I went with 1/8 because while contemplating a SLS I realized I would likely want to hang it with much more tension then the typical 30* hang, and wanted the extra margin to account for the derating using knots. When I did the math I wasn't comfortable with the margin using 7/64. If I stay away from knots, or always hang close to 30*, then I agree with you, but for the small weight penalty, I was happier with the extra margin 1/8th provided.

Here's my math for others reading this.

7/64th min break strength 1400lbs. Derate to 40% due to knots = 560lbs. 20* hang with 200lbs in hammock puts 292lbs of force on line.

[SilvrSurfr]

Why is that?

There is no splice (and no soft shackle) that gives you 230% of line strength. It just doesn't work that way, to my knowledge. So that dog don't hunt.

It seems the OP is re-inventing an SLS of his own design, without the benefit of having tried any of it. So he's all in the theoretical world without any time in the practical world. The SLS is used by very few people - it's not sold anywhere, to my knowledge. So the attraction to the SLS is because the OP sees something in the SLS that is lacking in just whoopies. Personally, I'd say whatever the OP sees in the SLS (going less than 30% hang angle) is a chimera - it's just not there. From what I can tell, the added knots will derate the rope significantly as well.

There are simpler ways to hang a hammock, but I don't think the OP interested in that - by the way, 7/64 is rated at 1600 lbs, not 1400 lbs.

[sargevining]

You mention you tested this to 8K pounds, etc.

I have no doubt that you tested it, and don't doubt your veracity at all, but I'm curious as to how you tested.