Light Rigging?

How do you guys determine light rigging? Like when you use just a sling and steel beiner or a pinto loopie. Obviously experience and or intuition come into play buuuttttt. I was just wondering when to get out the heavy stuff. I always try to ask myself the question weather something is safe and necessary or am I/we just trying to get the job done.
Pictures of a light rigging situation and any advice would be cool. i.e.: weights, branch sizes, etc.
Thanks!

It would take to long to actually give the correct answer, too many variables.

Get this book. Learn to use the weight charts and know your gear and its capabilities. Use accordingly

http://www.amazon.com/The-Art-Science-Practical-Rigging/dp/1881956288

After u have been doing it awhile, u will get your own "spidey sense" and will be able to make that call quickly. When in doubt, use the big stuff, DON'T take unnecessary chances and always re-inspect your rig setup, right before you cut. No matter how bad the tree is or how big, there is a way to rig it, just may take a little more time to set up, this is where guys go wrong, they get impatient and think "that's good enough" or they wont climb out to get to that one perfect "spot". So then they rig big, using small gear and that's when bad things happen.

Thanks beans, I got em a couple weeks ago. I have been watching the dvd and reading the book. I am still just a little unclear as to what is considered light rigging. Doing some figures on shock loading I want to err on the side of caution but don't want to go overboard.
Could I get away with a omniblock and whoopie or loopie and 1/2" bull line or do I go with the tail block. I am buying my own stuff and not opposed to spending the cash but dont want to overkill it.

i seldom use "rigging" i use a short rope almost exclusively and more often then not put my wraps in where i am and run my own ropes
times i dont are generally safety motivated, if i dont want it to shock load, or if i need it to run or if its faster to have the ground guys do it
usually if its really big and theres a lot of rigging its better just to get a crane in
that isnt always an option tho, ive taken down some massive trees in some tiny holes already, 8 hours is the longest ive ever been in one tree and 6 hours on more then one occasion
my avitar is from a side job for a small local company, 6 hour climb, 3/4" rope, no pulleys or porta wrap and i set my rope twice
as was stated earlier theres so much that goes into a complete answer
do the research, then come up with a platform thats tried and true and makes sense to you
ive yet to see 2 climbers that did everything exactly the same, everyone has their own style of rigging and preferred knots
some of the things i do aint even in the book, i took something and modified it
as you grow and learn, youll develop preferred methods
always err on the side of caution, property and lives are at risk

Light rigging is generally considered to be stuff which is only just slightly too heavy to hold by hand. So we're talking 100~200lbs max. There isn't really much shock load when rigging branches, because they have enough sail area that they have a slow swing.

It's a frowned upon practice by some, but I use the tail of my climb line on occasion for light rigging. On smaller jobs, If i only have one or two groundies then I rig my own stuff in the tree. It's quite efficient, and works well if you have a tree that only needs a handful of small pieces rigged out due to tight spaces etc. You can use stubs as a 'porta wrap' in the tree, so think ahead and don't flush cut. I usually throw my tail over a branch above the piece I'm lowering, tie it off, then take 1 wrap on my stub. You can take a bunch of wraps if you need both hands for the cut. Make the cut, lower off, and you can free the rope instantly and move on.

If it's a big tree, then I've probably got a bigger crew. It's time to break out bigger ropes and lowering devices as needed. That way you can take bigger sections, and get the job done efficiently. Using light rigging in big trees is every bit as slow as setting up heavy rigging in small trees.

Shaun

My light rigging ends at a 500lb estimate with little to no shock load. It's usually limited to branches that can be handled on the ground with one or two cuts. ANY trunking duties call for heavy line and rigging.

I try to look at the job and figure out how I'm going to rig it, then decide what gear I'll need to do the job.

If it looks like it'll come down well in 100lbs chunks for example, then I'll design my rigging system to handle that.

If it looks like it'll be 400lbs chunks, then the rigging needs to be heavier.

Once you learn to calculate dynamic loads it's easy to decide what rigging you'll need.

Carburetorless said:

Once you learn to calculate dynamic loads it's easy to decide what rigging you'll need.

Click to expand...

Perhaps you can explain it to us so we'll all know.....

ddhlakebound said:

Perhaps you can explain it to us so we'll all know.....

Click to expand...

The math for calculating loads is way over my head, and it isn't all that accurate anyhow. If you've got plenty of spare time have a read of this;


RR668: Evaluation of current rigging and dismantling practices used in arboriculture

It's a hefty 370 pages, and it's the most comprehensive study available on rigging methods used in our industry. The sections on math are pretty dry and not especially practical, but there is a lot of good info in there on tree safety assesment, how much load a branch can handle, best practices for rigging etc. There are some very good tests that measure forces in the text, and they make reccomendations on how to reduce your loads. Basically it comes down to reducing the size of the piece, reducing the distance of fall when negative blocking, and letting it run.

The test data on page 356 shows that tops typically reach a force (measured at the block) of 5-6 times their own mass, though it can be less. bear in mind that all forces are measured at the block where forces are doubled. This means that a branch typically creates a force of not much more than double it's own weight. The mechanical disadvantage created by the block doubles that force, for a net shock of 5-6 times the mass of the branch.

Logs however typically generate close to 10 times their own mass in shock force, measured at the block. This can be reduced by letting it run, but you can't bank on that. You have to assume worst case scenario which is 10 times. You may have the best groundie, but what if the rope jams?

There isn't much value in trying to calculate the force of any given take mathematically, but using these rules of thumb will create safe rigging scenarios.

In order to apply this info, we need to understand cycles to failure (CTF) as it applies to ropes, as well as other strength losses. Ropes lose their strength over time. Partly from abrasion and picking, but partly due to the stresses. Samson publishes a good chart that shows CTF for different ropes, to give you some idea, some ropes will have a CTF of 1000 cycles before failing if they are shock loaded at 20% of their breaking strain, but only 4 or 5 cycles if shock loaded at their full breaking strain. The short end of the stick is that if you apply heavy loads continuously to your rope, it will have a short life, and fail quickly. There are other strength losses due to knots also.

Now we are understanding that we need to keep the total 'shock' felt by the rope under 1/5 of its breaking strain. Some manufacturers tell you the Working load limit which is usually 1/5 of the breaking strain. Some tell you the breaking strain. Some say both.

So lets bring it home....

For a typical 5/8" bull rope, the breaking strain will be somewhere around 18,000lbs.

To make our rope last a long time, we need to give it a shock of no more than 1/5 of that. Which gives us a working load limit (WLL) of 3,600lbs

For branches (which we know can generate up to 5x their own mass at the pulley) this means we shouldn't be taking branches than more than around 700bs

For logs, which we know can generate up to 10x their own mass at the pulley, this means we shouldn't be taking picks much larger than 350lbs.

You can use these same rough formulas to work out the size of picks you ought to be taking on your own ropes. All you need to know is your ropes tensile strength or breaking strain. You only have to work it out once. You should of course also be using pulleys rather than natural crotching.

Some rough guides are;

typical 3/4" breaking 23,000lbs
WLL 4,600lbs
max branch 920lbs
max log 460lbs

typical 5/8" breaking 18,000lbs
WLL 3,600lbs
max branch 720lbs
max log 360lbs

typical 9/16" breaking 13,000lbs
WLL 2,600lbs
max branch 520lbs
max log 260 lbs

typical 1/2" breaking 10,000lbs
WLL 2,000lbs
max branch 400lbs
max log 200lbs

As you can see, you've got to get some pretty serious rope before you can go smashing down 1,000lb logs, unless you want to be replacing your rope frequently.

Shaun

ddhlakebound said:

Perhaps you can explain it to us so we'll all know.....

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Or I could just explain it to you, then we'd all know.

Lol, anyway,

There are charts you can use. They tell you the weight of different types of trees according to their diameter and length of the chunks(per foot). Find the type of wood you're dealing with, look at the chunk you're about to rig, and find it's weight on the chart. Once you do that you can multiply that weight by a factor of 3.5 and that will tell you the dynamic load of that chunk when properly lowered. A factor of 3.5 is probably a little overkill, but I figure it's better to err on the safe side.

For example, a chunk of Red Oak 4 ft long X 1 ft in diameter would weigh approx 200lbs.

200lbs * 3.5 = 700lbs or a 700lb dynamic load, if properly lowered. You'll need a rigging system who's weakest member has a tensile strength of at least 7000lbs, since 7000lbs/10% WLL = 700lbs

Most of the time though, my rigging is strong enough to take the load even if the guy on the lower line stops the load instead of letting it run, meaning the only time I really need to worry about overloading the system is if I'm bringing down really heavy chunks. So if you're bringing down really heavy wood, make sure the guy on the end of the lowering line knows what he's doing. And if you're not sure, don't rig anything heavier than what your system can safely handle if he locks the piece up.

BTW, if you lock a piece up, the dynamic loading factor goes from 3.5 to around 5, so that 200lb chunk goes from a dynamic load of 700lbs to a dynamic load of 1000lbs. If your system is designed to handle 700lb dynamic loads, then you'll be overloading the system, and weakening it at rate that will cause premature failure. It likely won't snap the first time you overload it that way, but it'll get weaker faster, and it'll end up failing way sooner than you expect it to. So a system you were going to retire next year, could end up failing you next month.

Carburetorless said:

Or I could just explain it to you, then we'd all know.

Lol, anyway,

There are charts you can use. They tell you the weight of different types of trees according to their diameter and length of the chunks. Find the type of wood you're dealing with, look at the chunk you're about to rig, and find it's weight on the chart. Once you do that you can multiply that weight by a factor of 3.5 and that will tell you the dynamic load of that chunk when properly lowered. A factor of 3.5 is probably a little overkill, but I figure it's better to err on the safe side.

Most of the time though, my rigging is strong enough to take the load even if the guy on the lower line stops the load instead of letting it run, meaning the only time I really need to worry about overloading the system is if I'm bringing down really heavy chunks. So if you're bringing down really heavy wood, make sure the guy on the end of the lowering line knows what he's doing. And if you're not sure, don't rig anything heavier than 300 lbs.

Click to expand...

:taped:

Carburetorless said:

Or I could just explain it to you, then we'd all know.

Lol, anyway,

There are charts you can use. They tell you the weight of different types of trees according to their diameter and length of the chunks(per foot). Find the type of wood you're dealing with, look at the chunk you're about to rig, and find it's weight on the chart. Once you do that you can multiply that weight by a factor of 3.5 and that will tell you the dynamic load of that chunk when properly lowered. A factor of 3.5 is probably a little overkill, but I figure it's better to err on the safe side.

For example, a chunk of Red Oak 4 ft long X 1 ft in diameter would weigh approx 200lbs.

200lbs * 3.5 = 700lbs or a 700lb dynamic load, if properly lowered. You'll need a rigging system who's weakest member has a tensile strength of at least 7000lbs, since 7000lbs/10% WLL = 700lbs

Most of the time though, my rigging is strong enough to take the load even if the guy on the lower line stops the load instead of letting it run, meaning the only time I really need to worry about overloading the system is if I'm bringing down really heavy chunks. So if you're bringing down really heavy wood, make sure the guy on the end of the lowering line knows what he's doing. And if you're not sure, don't rig anything heavier than what your system can safely handle if he locks the piece up.

BTW, if you lock a piece up, the dynamic loading factor goes from 3.5 to around 5, so that 200lb chunk goes from a dynamic load of 700lbs to a dynamic load of 1000lbs. If your system is designed to handle 700lb dynamic loads, then you'll be overloading the system, and weakening it at rate that will cause premature failure. It likely won't snap the first time you overload it that way, but it'll get weaker faster, and it'll end up failing way sooner than you expect it to. So a system you were going to retire next year, could end up failing you next month.

Click to expand...

I'm disappointed and stuff.....I thought we were going to hear about how to calculate dynamic loads.

Not that you heard that you should estimate the weight of the piece, multiply my a factor of somewhere between 3.5x and 5x. Seems kinda like guesswork.

I'm also a bit curious about *Most of the time*.......so how many rig ropes have you broken to get this figured out?

Carbie said:

You'll need a rigging system who's weakest member has a tensile strength...

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So what is the weakest link in your rigging chain?

And one last question......You make sure that everything you use in your rigging chain is rated for the loads you'll be applying, right?

Anyhow,
We've kind of wandered a little away from the original topic of light rigging. Do be conservative in your rigging, especially when it's on small ropes. If you're on 1/2" (the tail of your rope sometimes) then a couple hundred pounds will keep you safe. I almost never rig down blocks, It's just too hard on my gear and on me. It's slow too. I rig down sections where needed, but once it's blocking time those puppies are taking the express route.

Shaun

imagineero said:

Anyhow,
We've kind of wandered a little away from the original topic of light rigging. Do be conservative in your rigging, especially when it's on small ropes. If you're on 1/2" (the tail of your rope sometimes) then a couple hundred pounds will keep you safe. I almost never rig down blocks, It's just too hard on my gear and on me. It's slow too. I rig down sections where needed, but once it's blocking time those puppies are taking the express route.

Shaun

Click to expand...

I like bombing chunks but sometimes you can't. I recently chunked down tree that was on a pretty short steep slope with a house at the bottom of the slope. I didn't catch and lower the chunks but tag lined them so they wouldn't roll down and bounce into the house......slower than the "hope" method (As in I hope those don't hit the house) but faster than lowering each piece.......

I usually use light rigging until something breaks then I switch to heavier stuff.....No not really........

Stayalert said:

I like bombing chunks but sometimes you can't. I recently chunked down tree that was on a pretty short steep slope with a house at the bottom of the slope. I didn't catch and lower the chunks but tag lined them so they wouldn't roll down and bounce into the house......slower than the "hope" method (As in I hope those don't hit the house) but faster than lowering each piece.......

Click to expand...

I try not to bid on those kinds of jobs ;-) Unless there's crane access!

I can usually get away with a good crash pad of limbs with foliage on, and a perimeter fence made out of chunks of log or whatever is handy. If the tree is huge then it doesn't work so well, but then we're back in that same circle.... If it's huge, I don't want to rope the blocks down, I'll get a crane in, or not bid on the job. You're certainly well beyond 'light rigging' when your roping blocks down out of big trees. I've tried the vertical speed line method a couple times, but it was a bit hit and miss trying to get the slings or rope to stay on the chunk. On big trees they're going to be wider than they are tall. You can cut grooves into the block, or holes, or use lag eye bolts etc, but thats starting to turn into a lot of time.

I want a good guy on the rope for negative rigging, someone with a light touch. You can take a lot of the shock out if you have a GRCS or a friction drum. I've got a friction drum. With negative rigging you can use a 'snatch and release' method. You can't snatch with a porty. With a drum, you take the appropriate number of wraps, but don't take any tension. As the chunk is released, you can quickly snatch out all the slack while it falls. You've got to be quick about it, and the snatch is done with your arms (not your body). It's kind of like hooking that big fish. The release is done with your body. It happens immediately after the snatch, and you put it into effect by letting the rope pull your whole body towards the tree, either running or a fast walk, and slowing it down over a few paces. You want to get that block well away from your climber, so leave enough distance between yourself and the tree to do it. I find using your body for the release is a lot more controllable and smoother than trying to let the rope run through your hands. It also lets you get away with less wraps, which gives you more feel/finesse.

When it's executed correctly, it's a seemless motion. The block falls, you snatch the slack quickly with your arms, then your whole body moves towards the tree quickly and slows the descent down.

You can still use the whole body release method with a porty or other lowering device, but you won't be able to snatch it. It's a little harder to get a smooth take up since there's going to be a jolt unless your timing is really perfect.

Shaun

ddhlakebound said:

I'm disappointed and stuff.....I thought we were going to hear about how to calculate dynamic loads.

Not that you heard that you should estimate the weight of the piece, multiply my a factor of somewhere between 3.5x and 5x. Seems kinda like guesswork.

I'm also a bit curious about *Most of the time*.......so how many rig ropes have you broken to get this figured out?



So what is the weakest link in your rigging chain?

And one last question......You make sure that everything you use in your rigging chain is rated for the loads you'll be applying, right?

Click to expand...

Since you're so much smarter than the rest of us; Why don't you tell us how you do it?

imagineero said:

Anyhow,
We've kind of wandered a little away from the original topic of light rigging. Do be conservative in your rigging, especially when it's on small ropes. If you're on 1/2" (the tail of your rope sometimes) then a couple hundred pounds will keep you safe. I almost never rig down blocks, It's just too hard on my gear and on me. It's slow too. I rig down sections where needed, but once it's blocking time those puppies are taking the express route.

Shaun

Click to expand...

I've been considering adding land scraping to my business to. If only I could come up with a way of pulling those chunks of wood out of the ground after I bomb them down. umpkin2:

Carburetorless said:

Since you're so much smarter than the rest of us; Why don't you tell us how you do it?

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I'm not the guy who said

Once you learn to calculate dynamic loads it's easy to decide what rigging you'll need.

Click to expand...

.

I think that was you.

ddhlakebound said:

I'm not the guy who said .

I think that was you.

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Sometimes I think you're bipolar.

Carburetorless said:

Sometimes I think you're bipolar.

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So now you think you're a psychiatrist too? Get over yourself Carbie.

Care to answer the ???'s I asked earlier? Is it that you don't know, or that you'd rather just spread #### like it's peanut butter?

Maybe if you stopped making BS statements like "Once you learn to calculate dynamic loading......", when you really don't know, you wouldn't get called out for being full of it.