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Chockstone Forum - Climbing Videos

Post links and comments about your favourite climbing flicks

Author
Rigging Anchors for Balanced Load
kieranl
29/01/2014
9:54:40 AM

Not climbing as such but a really good tutorial from Rob Stringer of angles and forces in anchors.

Goshen
29/01/2014
1:00:30 PM
interesting... so...

slackliners had better get their anchors pretty right if the line is tight (160-170deg)!

up to 90degress is fine (it's what we're all told), especially for top belays; but

focal point in the video is a ring (or mallion would be the same); but if it's a carabiner - beware that it would be a 'cross loaded' carabiner at any angle greater than 90deg? So use 2 carabiners to a sling / rope focal point.

projected load lines is interesting too - in climbing the 'load line' would rarely be 'bicecting the angle'... I'm learning lots of new technology :-) But it's obvious I'd imagine that the ancor receiving the highest load line had better be a good one.
kieranl
29/01/2014
1:07:17 PM
On 29/01/2014 Goshen wrote:
>interesting... so...

>projected load lines is interesting too - in climbing the 'load line'
>would rarely be 'bicecting the angle'... I'm learning lots of new technology
>:-) But it's obvious I'd imagine that the ancor receiving the highest
>load line had better be a good one.

Projected load lines get more interesting when you increase the number of anchors, which is the classic issue with cordelettes. I suspect (hope) Rob will address that in a video.

shortman
29/01/2014
1:09:10 PM
On 29/01/2014 Goshen wrote:
>interesting... so...
>
>slackliners had better get their anchors pretty right if the line is tight
>(160-170deg)!
>
Or use ridiculously over rated gear @ anchor points.
One Day Hero
29/01/2014
1:33:00 PM
Bogan physics is cool. I was convinced that I wouldn't learn anything by watching that video, but now I know that ridgey-didge is a good approximation of 120 degrees and up yours is about 30 degrees. Sweet!

The good Dr
29/01/2014
1:48:00 PM
On 29/01/2014 One Day Hero wrote:
>Bogan physics is cool. I was convinced that I wouldn't learn anything by
>watching that video, but now I know that ridgey-didge is a good approximation
>of 120 degrees and up yours is about 30 degrees. Sweet!

... and the bird will always give you the projected load line.
kieranl
29/01/2014
2:30:39 PM
On 29/01/2014 One Day Hero wrote:
>Bogan physics is cool. I was convinced that I wouldn't learn anything by
>watching that video, but now I know that ridgey-didge is a good approximation
>of 120 degrees and up yours is about 30 degrees. Sweet!
And you can go and buy the iphone app for measuring 90 degrees. I believe it will be ported to android shortly.
brendan
29/01/2014
3:24:29 PM
here is a video on tensioned lines for rope access, the physics translates across to slack lines too

http://www.youtube.com/watch?v=cObvjbVO3ro

won't let me embed the video
kieranl
29/01/2014
3:38:30 PM
On 29/01/2014 brendan wrote:
>here is a video on tensioned lines for rope access, the physics translates
>across to slack lines too
>
>http://www.youtube.com/watch?v=cObvjbVO3ro
>
>won't let me embed the video
Created a separate topic for this video as per the forum guidelines. No problem with embedding that I could see (and this is only the second time I've embedded a video).
brendan
29/01/2014
4:25:04 PM
Why does it need it's own thread? It's pretty much the same as the originally posted video
kieranl
29/01/2014
4:57:58 PM
On 29/01/2014 brendan wrote:
>Why does it need it's own thread? It's pretty much the same as the originally
>posted video
It's easier for people to find it. The idea of the videos forum was a topic for each video I believe.

plumb-bob
30/01/2014
3:10:56 PM
"focal point in the video is a ring (or mallion would be the same); but if it's a carabiner - beware that it would be a 'cross loaded' carabiner at any angle greater than 90deg? So use 2 carabiners to a sling / rope focal point."

Goshen, you're correct if you're using two separate slings attached to a single crab as per the video, but an easier way to overcome this would be to use a cordellette and tie an equalised tie-in point / master point or 'power-point' and then connect your 'load' to a single crab connected to this point.
kieranl
30/01/2014
8:08:42 PM
On 30/01/2014 plumb-bob wrote:
>"focal point in the video is a ring (or mallion would be the same); but
>if it's a carabiner - beware that it would be a 'cross loaded' carabiner
>at any angle greater than 90deg? So use 2 carabiners to a sling / rope
>focal point."
>
>Goshen, you're correct if you're using two separate slings attached to
>a single crab as per the video, but an easier way to overcome this would
>be to use a cordellette and tie an equalised tie-in point / master point
>or 'power-point' and then connect your 'load' to a single crab connected
>to this point.
Maybe "easier", but is a powerpoint knot simpler? You've taken a simple system where you can easily understand the forces at play at any point and put in a complex knot which is only superficially easy to understand. What are the forces at play inside the knot? Is the load on the krab coming along its axis or are some of the knot-loops loading the krab away from the axis (akin to a wide tape sling)? How easy is it to do fine adjustments at the knot without untying it? The relative strength of simple knots is fairly well known but what's the strength of any particular powerpoint knot?
It's not that I think they're dangerous for climbing applications, they've been used for years. But if you want to build an anchor system where you can understand the forces at play at any point then they're a complication, in my view.


There are 13 messages in this topic.

 

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