Loopie sling strength rating

treesmith

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Could any of you rope/rigging experts explain to me why a loopie sling is rated twice as strong as a whoopie? I understand that it's doubled around the tree, but at the point of block attachment, there is ONE leg of the sling running through the block...just like the whoopie. Seems that this would be the weakest point and that the rating should come from there.

I bought up some tenex and made up a bunch of whoopies and eye slings. Now I'm considering some loopies, but I never read of them in use on here, and the strength rating seems misleading.

Any thoughts??????
 
A whoopie has one leg at it's thinnest spot (between the eye and the adjustable eye), a loopie has two (it's a loop after all).

I made a one or two whoopies before going to loopies. Not so much for strength as adjustability.



Nice job in Vernon.
 
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  • #3
I understand that the whoopie has one leg vs. the loopie's two, but it seems that the weakest point of the loopie is where it runs through the block. I'm sure the loopie is stronger than the whoopie because of its inherent design, I just can't see it being twice as strong. The load at the block is double (assuming verticle load), so all that weight is on the single leg running around the block's anchor bushing.

You saw me in Vernon?
 
Both have dual legs going around the block's eye. A single leg would require a knot or it'd fall off.

A whoopie has one leg, where a loopie has 2.

Whoopie.jpg



I saw your stumps (according to one of the city guys) on 1st Ave NW.
 
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  • #5
I understand that the sling runs through the block...hence two legs (effectively). What I mean by a single leg is that the weight of the rigging will be on a single thickness of the sling. (There is only one thickness actually contacting the bearing side of the sheave.)

I'm not very computer savvy or I'd post some pictures explaining what I mean. Maybe I can figure out how to post pics.
 
The eye is not where the strength reduction comes from.

And if there were 2 layers of sling around the eye, all 4 legs captured, the eye would be 4x as strong.
 
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  • #7
sli402-2-500.gif


Here's the loopie. All the weight would be applied to one thickness of the sling where it meets the bottom of the block sheave.

sli302-500.gif


Now here's the whoopie. Assuming a block were attached instead of the portie, again, all the rigging weight would be applied to one thickness of the sling where it meets the block's sheave.

Even loop slings are rated at different capacities for girth vs. basket hitching. That's sort of what I'm getting at in comparing the loopie and the whoopie.
 
What does "one thickness" matter? You have 2 load bearing legs either way. The strength difference is where the whoopies 2 load bearing legs become a single load bearing leg in the picture I posted above.

Any sling will have different ratings for a basket (4x) vrs a girth (normally 1.6x).
 
Because there's is two legs. The strength loss in a girth hitch (normally approximated to 20% of the basket) is due to the rope being bent over itself. The sharper the angle, the more stregth that is lost.


ETA: In your second picture, in a perfect world, the eye of the whoopie should be big enough that the loop of the girth hitch falls on the 2 legs of the eye instead of the the throat.
 
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  • #12
I simply wondered how the loopie could be TWICE as strong as the whoopie. Just curious mostly. I see where it would be quicker/simpler to adjust than the whoopie. I just wondered where they come up with rating it twice as strong. It makes no difference, as I'm going to make some up anyway. I simply wondered about the strength.
 
Because the loopie has 2 legs running all the way around the tree whereas the whoopie necks down to a single leg at my arrow above.
 
We just broke a whoopie, massive redirect loading.
Pulling a good sized back leaning cypress over.
The girth hitch was about 5 inches south of the spliced eye.

Pulling with a 3/4 samson.
The block shot about 60 meters.

The whoopie sling failed as the girth was not pushed down to the block,
not Using both legs of the spliced eye to capture the girth.

I saw it before the pull but didn't say anything, well now I know to say something.
 
Or look at it like this. Pulling end to end, you can see how tying a loop doubles the strength of the line, right? (Excluding strength loss from joining the ends) That's essentially what a loopie is, an adjustable loop.

A whoopie is nothing more than an eye to eye sling with one eye being adjustable in size.
 
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  • #16
Gotcha. I'll take your word for it.

I got rather tired of adjusting a whoopie the other day. Depending on the size of the rigging point, sometimes I attached it normally, other times, when the attachment point was somewhat smaller, I wrapped the whoopie twice rather than shorten it to save time. The loopie seems to have a definite advantage in that it will adjust down to a rather small diameter.
 
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  • #17
I just discovered that I read the ratings wrong. I was looking at my Wesspur catalog. The ratings were for basket, single-leg and choker, respectively. I understand that the loopie would be twice as strong compared to the whoopie if the same attachment method were used.

Like Skwerl said, I was thinking of the eye as the weakest point, thereby yielding the same strength for both.
 
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  • #19
How much do you allow in the "lapped" portion? Is there a rule-of-thumb to go by?
 
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  • #21
What size do you use most? I was thinking of making up some 1/2" and some 5/8".
 
I bought a ton of 3/4", and a ton of 1/2". 3/4" is all I use, for mounting pulleys and eye slings.

I had the 1/2" first, but just decided to use all 3/4". There's no real thought process on which one I should have the guys grab. I like minimal choices and keeping it simple.

I also have 100' + of 3/8. I have a mini porty mounted on some of that, and a couple small loopies for my saddle that I thought I'd use and never do.

I get caught in the moment sometimes and end up with all this rope I think I'm gonna use. In the end I just keep it basic.
 
sli402-2-500.gif


Here's the loopie. All the weight would be applied to one thickness of the sling where it meets the bottom of the block sheave.

sli302-500.gif


Now here's the whoopie. Assuming a block were attached instead of the portie, again, all the rigging weight would be applied to one thickness of the sling where it meets the block's sheave.

Even loop slings are rated at different capacities for girth vs. basket hitching. That's sort of what I'm getting at in comparing the loopie and the whoopie.

Treesmith- I didn't read the next two pages of the thread, but I think what Carl is explaining (and I agree with him) would best be understood if you looked at what is happening at the back side of these same pics you posted.

The whoopie gets down to one leg at one point, whereas the loopie always has 2 legs supporting the load.

Welcome to the House!

love
nick
 
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