Rigging w/ biners, instead of a knot..?

[TreeJunkie]

Some guys who i work w/ have gotten into the habit on the ground lines: which have spliced eyes;placing a steal biner 50kn and using this as a faster way to connect w/ rather than using a running bowline or the like.....THis seems fine to me in some situations>.However it does worry me when lowering heavier material. B/c of the way the load is applied, i don't think the biners are intended to be loaded this way....
I do like the idea that by using a spliced eye you are keeping a greater amount of your SWL;by avoiding using a knot...
Does anyone have any suggestions or Thoughts on this???

 

[jamie]

aye

i know a company who use retired biners for this, remove the locking gate and well they get used for rigging, easy to 'tie and untie' no more wretling with a knot that is under the log/limb that is wedged ion while the climber is getting pissed

jamie

 

[Lumberjack]

Proper splices are stronger than any knot.

So a spliced eye, and biner is ok in my book as long as it is properly done.

To use the biner you must have a sling, I perfer the loopie, in the size for the load. The steel biners that I use are rated to 65kn (gearexpress). Steel and aluminum for that matter have better fatigue properties than rope, meaning that their SWL is a larger percentage of their tensile.

IMO shock loading, such as blocking down heavy spars, would hurt the rope more so than the biners. And using the knotless system is normally faster.

What do you mean by the biners arent meant to be loaded that way?

 

[jamie]

slings

we dont normally use slings, maybe we (as a company) are a bit simple and only really chocker the rope round the limb tie an knot and cut......

if its over something the bits get smaller

jamie

 

[Lumberjack]

Yeah I didint think of that, and that is what I do the most of, wrapping, and then clipping. I always make 2 wraps, like rocky said, to load the wraps instead of the binner. On smaller stuff I make 3. Any smaller than that and I use a loop made from 1" nylon tubing and a beer knot.

 

[TreeJunkie]

What i meant by loading a biner that way, was b/c the way biners are tested is on a straight pull,,,not being bent around a log or brandch, i would think this would strain the biner differently than that of which they are originally designed..

 

[NickfromWI]

Most carabiners are not designed to be shock loaded by heavy pieces of wood.

That being said, I used to work with a guy who used the same setup. When I started there, he was using 1/2" bluestreak with a snaphook (like the kind on a flipline) tied to it. I saw that setup withstand some phenomenol loading....shock loading thousand pound pieces of wood and things like that. However, it scared the heck outta me! Before I left, we set him up with 9/16ths Yale Double Esterlon spliced rigging lines and the 50kn steel 'biners. I reccomended he not take any bigger wood that what he uses now, as he was really pushing the limits...but I'm not there anymore to see what he's doing!

So, yeah, it can be done. I wouldn't say that it's good to do it, though.

love
nick

 

[Tom Dunlap]

The balding grey haired climber has to chime in here

When I started doing treework back in the ancient days of the late sixties, we used half inch three strand with a rope snap splice in the end. It was really jaxxy when we started to use thimbles..woo who!!!

This was in the day of Dutch Elm Disease spreading like wildfire. We would to a single wrap and snap back onto the rope itself. Then take a wrap...or two...or ??? In all those years and tons of rigging, in natural crotches too, we never had a rope break or a snap bend.

All that said, I wouldn't want to go back to that method of rigging for a second.

Like Shigo says, it's all about dosage. Using a 50kN biner to rig out limb wood is probably going to be OK for a long time. Slam dunking, well, do the math first.

I've been concerned with choking biners onto wood for a while too. There are so many better solutions, why not use them?

Using slings is great. If the wood is choked most of the time the biner/snap will end up under the log. You'll find pretty good odds if you're a betting climber. With a sling it makes no difference if the choke is on the bottom, leave it and grab another sling. You'll cut and roll the log later.

Tom

 

[TheTreeSpyder]

i think of this as a reusable running bowline; in trade for a nice built in throwing weight and modular sectioning; you have to be careful of the side loading like Rocky says.

When using a running bowline, for increased/double grab; and to keep the main load off of the knot; i go with a half hitch preceding the running bowline. The 2nd choke of the running bowline being towards the heavy end/C.o.B.; so that they both pull closed positively. i think Sherrill's strategy of a longer eye on slings etc. is to avail less direct loading to the joint of the splice; is good in this form too.

i think that the half hitch, running carabiner strategy would put lots less on the carabiner/snap than a roundturn and 'capture' strategy; as the carabiner & spliced or bowline eye would still get more of the full load with just a round turn. i first tried stuff like this with old lanyard etc. snaps; using it as a way to use-up non-safety ones(both manufactured and 'dis-armed' snaps) at one guy's tree service. So i image those witrhout carabiners can try this.


Bending a flat carabiner around a roundish/non-flat surface would leverage/sideload the carabiner. Increasing the force on the carabiner many times, and applying that leverage at the carabiner's weakeast axis of support; both compounding against the SWL, and perhaps weakening the structure for a future faillure(?); if not presently. If the carabiner/snap/running bowline is set to meet it's host (to form choke grab ring) at flatter than 120deg.; you really start to leverage the line on both sides of that choke past the weight/force of the load*; in crane loads this is where the warning of not to hammer the (esp. stiffer cable) cable choker flat to the load, as to not leverage it that way. The extra grip of it being choked tight has to come from somewhere; this is it. This extra leveraged force would also pass thru the carabiner, for even more compound leveraging (on top of torquing it across a curved surface, at it's weakest angle of structure)>IMLHO.







* If the choke meets and forms a 120 deg. angle at that meeting, each leg of that choke starts around the load carrying 1x the load force itself. At 150 deg. that is each leg 2x load; jumping to almost 3x at 160deg; accelerating loading greatly from that point.

edit-i favour choking with slings for even more modular assemblies and utilities as Tom speaks of, using these above strategies as backup.


Or something like that............
:alien:

 

[dbeck]

I have never heard of a running bowline breaking under load, but I have heard onseveral occasions of side loaded carabiners (like you folks speak of) breaking under load. This tells me something...like you shouldn't do it. That being said, I have never done it.
However, I have been involved in knotlesss rigging where there is a locking ladder snap or biner in a splice attached to a loopie girthed around whatever is being lowered. This seems to be the acceptable scenario IMO.

 

[Lumberjack]

Shock loading a biner, as long as the shock stays in the SWL is ok in my book. The rate of application doesnt matter as much as the amount applied.


Edit: When using slings, like loopies.

 

[NeTree]

I use biners sometimes, and like Rocky, I take a wrap... but more for the extra "grip' on the wood than to reduce the load on the biner.

 

[John Paul Sanborn]

For general rigging I like slings and a carabiner.

I like a fishermans knot on the end because it falls apart real easy onec the carabiner is off. Then i can use either end of the line whenever I want.

When on heavier wood I will take the carabiner off and use boline and a marl.

In some medium sized wood I will do the high strength tieoff (take two wraps and clip off) especially if I'm real close to the block and may want them to suck the peice up into it.

A marl or halfhitch and under the bo'lin will reduce the reduction factor of the boline signifincatly.

I'm not so muc afraid of it breaking right then, but it is a "cycles to failure" issue with me.

 

[NeTree]

My rigging biners are rated at 65kn, and they're steel.

I'm not worried about a 100# limb breaking it.

 

[MasterBlaster]

 

[NickfromWI]

I'm not worried about the hundred pound limbs breaking it. It's the 1500lb limbs that I'm worried about!

love
nick

 

[geofore]

biners\rigging

50kn and up, steel, is easy on the groundman that can't tie or untie a knot. When is the last time you ran into a groundman like that? When I used a clevis the guys would not wind them in tight, but I used them because I had them from working steel. My mistake, the guys figured they were tight enough with a few twists because they were steel, NOT! With a biner make sure to lock it if you use it. Just to snap it is not enough, it needs to be locked. When it takes a shock load it could open, if you use it, LOCK IT! It makes a difference.
Tom, I know where your coming from, 1/2" three strand.

 

[John Paul Sanborn]

Re: biners\rigging

Originally posted by geofore

Tom, I know where your coming from, 1/2" three strand.

He for got to say Manilla too

 

[MasterBlaster]

I'm sure Nick was referring to the heavy ones, in general.

 

[Lumberjack]

Originally posted by MasterBlaster

I have started using a running 8. It is stronger, and easier to tie when I cant see it (other side of the tree or whatever) and it is easy to check and TDS.