what size top and or trunk to drop on a 1500WLL

my rigging system is 1,500WLL and 15,000MBS , I am going to be dismanteling a large fir. I would like to play it safe with my new equipment, but have almost no math skills
Please let me know 1)what is the best diameter to climb to to drop the top off.
2) what size pieces of trunk to drop. please help.thanks

inbilya@netzero.com wrote: my rigging system is 1,500WLL and 15,000MBS , I am going to be dismanteling a large fir. I would like to play it safe with my new equipment, but have almost no math skills
Please let me know 1)what is the best diameter to climb to to drop the top off.
2) what size pieces of trunk to drop. please help.thanks

There are load charts available to estimate weight per foot based on diameter and species, a Google search should turn something up for you. The most important thing to consider is how are you rigging? For example will you have a helper on the ground to handle the rigging rope and will you have a friction device such as a portawrap to allow the top and subsequent chunks to run after you cut them? The top is the most dangerous in this regard, if you dump a fir top on a static rigging system you could suffer some serious whiplash or worse (death).

As far as how large the top should be, the answer is: as small as possible. Climbing high and safely is easy, throwing a large top is more of a roll of the dice unless you have significant experience and trusted/experienced ground help.
-AJ

my rigging kit is the #3 kit from wesspur, consists of 5/8 double braid Samson rope, large portawrap and cmi 3/4 block and of course the slings. I have the green log chart. I am working with someone who has some, but not a lot of experience. first will do a smaller maple using this equipment even though that one is much simpler . I could have just used my 3 strand and natural crotch it, but I want to make sure he learns to let the rope run and the amount of wraps to do.

here is my plan for the fir so far. clean the tree of all branches on my way up all the way to maybe 5" dia. clean more branches with pole saw on one side to make it light, leave other side heavy. drop the top, then drop logs not exeeding 8ft length and not exeeding 400lbs weight. fell last 20ft.
my question is - should I go higher to drop the top ? and what number should I multiply the 400lb pieces by to figure out how much load I will be putting on my rope?
I've plenty of experience felling and lighter rigging just never done heavy negative rigging. I read a lot on this subject and watched plenty of youtube vids, but nothing compares with some practical advice from people that've done it all their life. so every bit of info helps. thank you

Sounds like you're on the right track, I have similar experience to you (fairly new to work climbing). I would go less than 8ft. per section though, depends of course on how high or low you are on the tree. Being conservative won't hurt and you can gradually get a feel for it, smaller pieces first to see how the system behaves.

A friend just had a tall spruce removed from his yard by an experienced crew. When they topped it there was too much friction on the rigging rope and the climber was shaken up pretty good, the top of the stem smacked him in the chest hard.
-AJ

is there much weight in the top? (assuming I cut it at 5" dia)

are you saying if i drop a piece of 7-5 inch diameter I should still make it like 6ft length instead of 8?

another question will come up when I get down to about 30 inch diameter - is what is the shortest piece to cut that will still work with running bowline and half hitch without being in danger of loosing the piece due to it being so short?

thanks for the info and the warnings

You might be able to get more expert response on one of the working arborist forums like treebuzz.com.

In response to your question "how short a piece can be" before a Running Bowline will slip off... When I've done short heavy pieces I use a Clove Hitch and then back it up to keep it tight, create enough rope friction around the piece, it won't slip. In extreme cases with large diameter short sections climbers will sometimes cut a notch so the rope won't slip.
-AJ

thanks a lot for your help Moss. this really helps.

As Moss alluded to there is a science and and art to professional tree rigging. Knowing the limits of equipment and all is great. Matching the gear to the job imperative. However, do not forget that the weakest link, the link hardest to quantify is the tree itself.

Proper inspection, planing and hazard mitigation are all necessary. So to is a good mind set. Think not how large you can go, but how to fit loads into your rigging plan, abilities and situation. This is the art portion.

Look to rig not to your convenience, but to the stability of the rigging system and the tree supporting it. Rig in ways that reduce loading on the tree and system.

Generally speaking there are 5 ways to accomplish this:
1. Rig smaller pieces
2. Decelerate rigged pieces slowly. A.K.A let it run!
3. Put more rope in the system
4. Change the angle the rope enters and/or exits the block.
5. Use a more elastic rope.

Add these variables as often as you can! Number 1 and 2 are the most common and easiest to do.

Good luck, be safe!

Tony

thanks Treedude! this is all helpful. I actually wanted to know safe limits so that I could stay well below them to make sure my equipment does not get abused. I now recieved my rigging software from Sheriltree , just installed it earlier today. I have to say it is very helpful thing and easy to use . it is on sale now was $50 now $10 while supplies last.