Srt top anchor point - question

[Mark Bolam]

Nor me.

You been on the Saki Paul?

[D Mc]

.... the problem is that we thought the solution lay in a device that could move in 2 directions, the multiscender, that this would change an Access system into a Work Positioning one....

 

We have had bidirectional movement with ascenders for years. What we got with the new multiscenders is complete 3 directional, fluid movement and that is indeed what has allowed the safe use of a static/stationary single line for work positioning.

 

I still prefer a simple base anchor for virtually all my climbing other than removals.

[phedders]

I have begun to teach climbers to cut DdRT ropes in half. SRT climbers need new concepts.

 

Do you teach them to tdo that whilst they are in the tree?

How many of those are able to quantify if it was a good idea now?

 

I too don't understand your point there friend.

[phedders]

I still prefer a simple base anchor for virtually all my climbing other than removals.

 

Do you give much thought to the fact you are putting up to 200% of your weight on the top redirect point, which might be higher than you can see clearly before ascending and therefore might not be the best place to be putting 2x the normal load on when actually you might only get lucky putting 1x your load?

 

Just wondering. I'm not an arb... I can see the advantages of a base anchor - but it seems to me that a snug canopy anchor is inherently a lot safer (lower loading and only 'one' line to protect.)

[D Mc]

I actually give thought to most everything I do. Never trust your life to something you can't see. If you are not 100% sure, take another shot. A good suspension point should easily support 2x your climbing weight. The force multiplier has mitigaters in the form of friction and rope angles.

One of the great things about base anchors is being able to use the tree's structure to your advantage. When you open up your rope angles by catching more then one crotch, you are not only reducing the force multiplier but you are reducing the side loading on those branchs and, instead, loading them more in comprehension. Much stronger, offers redundancy, and potentially keeps the base leg out of your work area.

[tipmethewink]

Do you give much thought to the fact you are putting up to 200% of your weight on the top redirect point, which might be higher than you can see clearly before ascending and therefore might not be the best place to be putting 2x the normal load on when actually you might only get lucky putting 1x your load?

 

Just wondering. I'm not an arb... I can see the advantages of a base anchor - but it seems to me that a snug canopy anchor is inherently a lot safer (lower loading and only 'one' line to protect.)

I'm not an arb either and I don't know the physics so I'm interested to understand how this is different to drt where the climber is on both "ends" of the rope? Is the force on each leg half the climbers weight in that case? Thanks.

[carlos]

grab your groundy and both have a good ol swing n bounce on any anchor be it single rope or double.

[phedders]

I'm not an arb either and I don't know the physics so I'm interested to understand how this is different to drt where the climber is on both "ends" of the rope? Is the force on each leg half the climbers weight in that case? Thanks.

 

First assuming a parallel load and anchor line:

You put 1x your weight on the line. The (base) anchor has to hold the same weight.. and so the top redirect has to hold both your load and the anchor load - so it gets 2x.

 

As the angle at the redirect reduces from 180 degrees, so does the load - think about it - reduce the angle to 0 (straight line) and there is zero load on the redirect. There are some natty graphs online that'll show you the ratios.

 

Now if you can avoid parallel lines by taking your anchor out and around the tree through a few redirects which are all less than 180 degrees, then each redirect gets much less than 2x the load - AND if you get it right, the angle of the load is directed into the branches rather than directly downwards. This puts more of a compression load on the branch than a bending (moment) load and is much less likely to lead to breakage.

 

This is what @D Mc was referring to - and was the perfect repost to my gentle dig

 

I've often pondered just lobbing the throw line right over the tree and setting a base anchor and letting the line settle in loads of branch ends. Probably not a good idea really

Edited October 12, 2015 by phedders

[Wooden Hand]

First assuming a parallel load and anchor line:

You put 1x your weight on the line. The (base) anchor has to hold the same weight.. and so the top redirect has to hold both your load and the anchor load - so it gets 2x.

 

As the angle at the redirect reduces from 180 degrees, so does the load - think about it - reduce the angle to 0 (straight line) and there is zero load on the redirect. There are some natty graphs online that'll show you the ratios.

 

Now if you can avoid parallel lines by taking your anchor out and around the tree through a few redirects which are all less than 180 degrees, then each redirect gets much less than 2x the load - AND if you get it right, the angle of the load is directed into the branches rather than directly downwards. This puts more of a compression load on the branch than a bending (moment) load and is much less likely to lead to breakage.

 

This is what @D Mc was referring to - and was the perfect repost to my gentle dig

 

I've often pondered just lobbing the throw line right over the tree and setting a base anchor and letting the line settle in loads of branch ends. Probably not a good idea really

 

 

English Lime's with obscene (and beautiful) epicormic branching - man, this takes me back, we had a row of 15 in Chelmsford, must be 2008/9, there were 2 options, a very slow and dirty internal attack or like you said just go over everything, which I did. It was the first time that I experienced an anchor breaking out, I dropped around 2 metres but the gazzilion other anchors that caught me made it feel like an eiderdown! In theory anything works but in practice, due to complex branch morphology, ideas show their pitfalls.

[Wooden Hand]

Nor me.

You been on the Saki Paul?

 

Ha, I love saki (sake), but no, not when I wrote that, you guys have to understand that I am 8 hours ahead so when you are settling in to your evening beverages I am going to work !

 

"Using a long rope creates unnecessary redundancy and so 2 short ropes, slightly longer than anchoring height (20-30M), will be used to create access, work positioning, traverse and retrieve lines. Ropes will be joined, separated, attached and de-attached dependent upon the task at hand."

 

I checked the stock lengths of Teufelbergers CE climb, 35, 45 and 60 metres, these lengths have been pretty much standard in the UK for as long as I can remember and it pertains directly to DdRT technique. What I was hinting at was the possible need to break away from DdRT rope work technique, rope length being one of them. The CE climb 35 metre system, one designed for small trees with anchors at and around 15 metres would be a long rope for me, anchoring at 25-30 metres.

 

Hope this makes a little sense ?!

Edited October 12, 2015 by Wooden Hand