Self tending climbing system

[Jamin_Mayer]

I am sorry, but I don't see how this is different from most folk's climbing systems. The hitch I use is self-tailing. (When at 50' or greater, the weight of the rope will pull itself through). Anyway, have you thought of a video of your system? Maybe that would allow me/others to visualize this in action. Check out my system. I have been using this for 4.5 years with no problems.

What do you think?

 

[Kevin]

[ QUOTE ]
What do you think?

[/ QUOTE ]

Do you think it's a good idea to have that hitch tied to the pulley in that manner?

 

[Cozmo]

I've seen the setup before and it's perfectly fine. The fixie pully from petzel has a peice of metal that goes across and I have seen some with beeline spliced to it instead of a knot. Thinking of it I think that system was ok'ed for a climbing competition in minnesota, the only catch I know of is the pulley is only rated for 4950lbs and not 5000.

 

[rich_h]

[ QUOTE ]
I am sorry, but I don't see how this is different from most folk's climbing systems. The hitch I use is self-tailing. (When at 50' or greater, the weight of the rope will pull itself through). Anyway, have you thought of a video of your system? Maybe that would allow me/others to visualize this in action. Check out my system. I have been using this for 4.5 years with no problems.

What do you think?

[/ QUOTE ]


The anchor bridge is designed so that you can ascend easily from the ground without any slack in the line. (Imagine your rope was set through a pulley or cambium saver at the top of the tree) This enables you to work the tree efficiently on the way up instead of needing to footlock your way to the top , tie in and then work one half of the tree on the way down and then go back to the top and work the other half.

Because you can easily go from ascent mode to working mode on the anchor bridge you can work your way up the tree (imagine a never before pruned pin oak) until you get to a limb that you need to walk out on. Once at that limb, just safety in and lower your knot so that you can now run out the limb easily. Once finished with the limb you can extend the system again and work up to the next limb. By working in this manner you can reduce your time in the tree by working half on the way up and the other half on the way down.

This system, when extended, is also a great substitue for foot locking up a doubled line. You can either foot lock up the single line with near full extension on each pull, or safety into the trunk and walk up the tree (much like when you spike up a removal). If you are using this system ( safety on trunk walking method) off a pulley you can get up the tree without using hardly any energy at all. Granted it will take you a bit longer to get to the top, but for those who are not very good at footlocking or are lacking upper body strength this is a great alternative.

Another benefit with this system when used in conjunction with an anchored pulley is that you are not footlocking up on a single isolated branch. You have the additional safety of having your anchor line over many branches. The key is that because you can now ascend with no slowing down, and no slack in the line you can take full advantage of your anchored pulley and your advanced climbing knot.


PS

I have used your system for climbing and it works very well for movement around the tree, but IMO suffers the same problems that other advanced climbing knots and set ups have by not being able to ascend very well.

 

[rich_h]

As to the video idea. It would sure help for visualizing the system in action. I will definitely work on getting that done. In the mean time, if per chance you are going to International I will gladly meet with you and go over the system with you and anyone else who is interested. I am sure there is more that can be done to make this system more efficient and I would love to get everyones input on what we can do to make it better.

 

[Mangoes]

Regarding the Fixe: calls were put into Petzl in Pitts. I belive by the ITCC commitee when the technique was proposed by a competitor. I was just a fly on the wall but I witnessed 'Silverback' coming back to report that Petzl said they would stand behind that setup on the Fixe.

 

[Lazarus2]

I have no concerns about the strength of the Fixe bar, especially the way a system distributes forces throughout it (ie often lower on certain components than one might think). This obsession about 5000lbs break strength of all components in a climbing system is misguided and certainly unecessary.

A simple case of 'Strength' compared to 'Security'.

I believe tieing in to the bar on the Fixe has security issues, because of the sharp edge acting like a knife on thin cord. Certainly over time with high tech cords that suffer from flex fatigue and possibly poor UV resistance.

Way up the advantages of pushing the boat out with such techniques, against just tieing in with nylon/polyester cord to the karabiner. Research attached by Black Diamond led them to stop selling their Gemini high tech cord. Because nylon did as good a job with none of the risks. A cordalette used in mountaineering has comparisons to prusik cord issues.

High strength prusik cords aren't necessary, and transfer heat back to damage the climbing line. 8mm nylon/polyester is plenty strong enough, UV resistant, flex resistant, heat resistant, has good knotability, feel and good energy absorption.

My tuppence worth to the 'tieing into the Fixe' debate. /forum/images/graemlins/crazy.gif

 

[Jamin_Mayer]

[ QUOTE ]
[ QUOTE ]
What do you think?

[/ QUOTE ]

Do you think it's a good idea to have that hitch tied to the pulley in that manner?

[/ QUOTE ]

Yes. The Petzl rep said it is just fine. And it is being accepted in the ITCC all around.

The Petzl Fixe pulley is not taking 100% of a person's body weight. I think it would only be taking 1/3 (or at the most 50%) of a climber's weight.---Can someone correct me on that?

Never the less, I think it is solid.

Petzl just needs to load rate that bridge on the Fise for us conscientious type. /forum/images/graemlins/wink.gif

 

[Jamin_Mayer]

[ QUOTE ]

I believe tieing in to the bar on the Fixe has security issues, because of the sharp edge acting like a knife on thin cord.

[/ QUOTE ]

Guote: "sharp edge acting like a knife"
/forum/images/graemlins/smirk.gif ---Seriously?

I'm sorry, but the edges Petzl creates are not sharp. They would know better. The "rope bend" is a slight issue in the debate, but we are talking about Bee-line or Thermashield cord here. Check out their specs. They are impressive!

When was the last time you tried to cut this stuff with scissors? /forum/images/graemlins/grin.gif

 

[Jamin_Mayer]

[ QUOTE ]
[ QUOTE ]
I am sorry, but I don't see how this is different from most folk's climbing systems. The hitch I use is self-tailing. (When at 50' or greater, the weight of the rope will pull itself through). Anyway, have you thought of a video of your system? Maybe that would allow me/others to visualize this in action. Check out my system. I have been using this for 4.5 years with no problems.

What do you think?

[/ QUOTE ]

Because you can easily go from ascent mode to working mode on the anchor bridge you can work your way up the tree (imagine a never before pruned pin oak) until you get to a limb that you need to walk out on. Once at that limb, just safety in and lower your knot so that you can now run out the limb easily. Once finished with the limb you can extend the system again and work up to the next limb. By working in this manner you can reduce your time in the tree by working half on the way up and the other half on the way down.


PS

I have used your system for climbing and it works very well for movement around the tree, but IMO suffers the same problems that other advanced climbing knots and set ups have by not being able to ascend very well.

[/ QUOTE ]

Rich:

You gave a perfect description there. I hate tight Pin Oaks. /forum/images/graemlins/crazy.gif

As to the "not ascending very well". I used to have a slight probleme with that, but the Blaze has taken care of that now. /forum/images/graemlins/wink.gif

I like your idea now that I can "visualize" it. /forum/images/graemlins/grin.gif

 

[Mangoes]

The leg of chord would be recieving %25 of the weight of the climber. One might be able to justify the use of a chord that has a tensile of 2700lbs because of this formula.

 

[Jamin_Mayer]

Mangoes:

How did you figure that out? Good job.

If it were true, then in my situation, I would be putting 37.5lbs on the pulley.--Anyone see a danger there?

 

[glens]

Each leg of main rope is carrying 50% of the total weight. Each leg of the cord is carrying 50% of the weight on that leg of rope. 50% of 50% of the total weight is 25% of the total weight. But that's "normally". In practice the load on the cord legs might not actually be 50/50, with the leg coming from the top of the hitch maybe carrying a bit more of the shared load.

 

[Tom Dunlap]

Rich,

Since you're going to be in Minneapolis you should consider having a setup with you all of the time. If you can make up one with a short piece of climbing rope instead of a regular length rope you will be able to demo the setup anywhere. Toss a rope over a doorknob, back of a chair or into a ficus at a department store and you're set to jet.

See you there!

 

[glens]

[ QUOTE ]
So the 'displayed' version is the one that appears when it is uploaded from my computer to a post? What if I resize, save-as (so I don't lose the original), and then upload the resized version that has been saved to my hard drive? Would'nt that be like the image on the right?

[/ QUOTE ]
I'll get to that in a moment. I checked in all three of the graphical browsers I might normally use. The third really never gets used to speak of, but the couple others I have in my Linux partition have only ever been used once or twice just to have a look at them and I believe they use one or more of the same layout engines as those in the first group of three. I tried viewing the full image in Konqueror (99.9% usage), Firefox, and Opera. Konqueror actually passes off image viewing (when the only thing being viewed is an image; not when an image is embedded within HTML code) to another program which embeds its output inside the Konq window (which I let it do for the test though for normal use I've opted to have it pass the task off to the standalone "display" component of ImageMagick instead). Both Konqueror and Firefox (Mozilla/Netscape) will shrink the image to fit entirely within the window with option to view it native size and scroll around (with Konq also offering infinite sizing steps). They both introduce the same type of artifacts as in the left side of my image attached earlier. Opera also automatically shrinks the image with option to view it various fixed sizes but does not exhibit the artifacts in any of the sizes as/when they are chosen. Opera is definitely a bit slower at making the changes, but not too bad.

I also bit my tongue and fired up the Windows XP SP2 partition which came on the computer and which I keep around for the odd BIOS upgrade I might encounter (they don't run on Linux, yet). [Let me tell you that running Linux and Windows back-to-back really shows just how sucky Windows is!] The IE version which came with that OS also automatically shrinks the image for viewing with the option to make it native size and scroll-around-able and it also exhibits the artifacts on the left image referred to above when the image is shrunk for full viewing.

Mahk, I don't know what your software does. I'd assume and hope that your saved-as version would be a clean one. If your software doesn't allow you to choose which "quality" level to use (shoot for no more than 75) or to "opt out" of the profile information (can be as much as 20KB per image) being included, then you definitely should consider fetching the ImageMagick stuff. One nice thing about it is that you can automate the creating of resized, rotated, etc. images whereby an entire directory structure can be processed by a single command.

Mahk has suggested in a PM that he'd be willing to copy all this stuff out to a new thread for ready reference and I think its a good idea.

Let me sum up a good set of guidelines:

There's no sense in uploading a JPEG image with higher than 75 quality level; one which contains profile information; or one which has pixel dimensions so large that the image will be shrunk within the viewing window in order to be fully shown.

The first two points prevent wasteful bandwidth/storage and the last one, along with that, will practically guarantee that the image will be shown without degraded detail. I'd be tempted to say that an image size of 1024×768 would be a reasonable maximum, but if the image were rotated 90° then it would be too tall and likely be resized-for-display as well. A better rule of thumb would be 800×600 (600×800).

I know many of you would say that's too small, but consider how much more/better detail you'd see in an image of that size, being fully shown unshrunk than it would have when shrunk for display in any of the browsers you're probably using. If you want fine detail in just part of your image, crop that out first and limit the result to reasonable dimensions.

As an added benefit, virtually every image having all the above qualities would be downloaded by every visitor. I can tell you from personal experience and from correspondence that many of y'alls pics get left unviewed because of the hardship involved in fetching them over a dialup connection. It's even worse when after all the time/trouble they wind up getting displayed poorly anyway!

Think about it, won't you?

 

[richhoffman]

Does anyone who is tying to the "brcket" of a Petzel Fixed Pulley has any hitch release issues?

It seems that since the pulley cannot "float" is sometimes causes the hitch to not fully release.

 

[Rupe]

Instead of tying onto the bridge of the Fixe, I've seen it done where the end of the cord goes under the bridge and is just tied off with a stopper knot. Figure eight or similar.

Whilst I'm a bit unsure about this, I have tried it and it seems ok. It would reduce the bend ratio of tying around the bridge, and lessen any knife edge action there too.

 

[Norm_Hall]

[ QUOTE ]
Does anyone who is tying to the "brcket" of a Petzel Fixed Pulley has any hitch release issues?

[/ QUOTE ]

I have tried it on the Kong version with the same results. The pulley doesn't line up true to the climbing line and isn't as smooth.

 

[Lazarus2]

Not literally 'a knife' /forum/images/graemlins/shakinghead.gif

The bend ratio is very poor. Which isn't good for any cordage. To compound this, many high tech cords have very poor flex fatigue characteristics. Watch a sailor dealing with a kevlar sail - any sharp bend when putting it away and its ruined. A bend ratio like tying in to the fixe bar is less than 1:1. A 1:1 ratio gives around a 50% strength loss, which is why knots are often rated as reducing break strength by 50%. Hence an edge less than this is likely to act as a knife (a very blunt knife), i.e. the cord can fail at way below its rated strength.

Some of the posts here talk about how much load is on each leg of the hitch. But it depends how you tie the hitch. In the overload tests I did on hitches, some failed twice in one pull! That was because the cord melts and grips, especially if the legs of the hitch cross over and under each other; one leg would fail, but the remaining leg would still hold until further overloaded.

Think about the cords you are using and where - high strength does not compensate for all factors that may lead to failure. I have concerns about some high tech cords that have very low UV resistance. when spliced, they are only dipped in a resin, and the polyester cover removed. Once the resin wears, what is daylight doing to your safety factors - especially in hot climbs. Some of these cords also have poor flex resistance (i.e. weak when knotted, getting weaker all the time). More concern.

Why risk it? nylon is perfect, cheap, easily knotted and therefore easily replaceable in the field. I have seen spliced high tech cords on audits in the field, that really should've been replaced. But because of the cost of the cord and splices, was kept in service. Splices don't grip the karabiner as well as scaffold knots either, enabling the krab to side load. If the cord isn't replaced because it isn't visibly wearing, that means it is going to stay in service suffering UV damage.

Food for thought.

 

[Leon]

I think you're overly concerned about UV damage to the high tech cords. I sail on racing boats regularly and the bare high tech cordage we use (technora, spectra, vectran) sees MONTHS of direct sunlight before replacement, and is regularly exposed to shock loads. This is way more abuse than the spliced eye of a hitch cord will ever see, at least in terms of light exposure, if not also in dynamic loading.

You also mention the cord melting to breaking in your tests. Cords with some of the higher tech fibers in the cover will have a much higher melting point and won't have this as a concern.

I'm not knocking cheap polyester hitch cords. They work great. I just don't see your point in knocking the high tech cords. You say "Why risk it?" as if they are inherently unsafe, which they are not. A break test of a knotted high tech cord versus a knotted, or even spliced polyester cord will see the high tech cord win any day of the week. Each one has it's advantages and disadvantages.