UKC

I've been thinking about this for a while now and over the wet Xmas hols, experimented.

See http://personalpages.manchester.ac.uk/staff/chris.tan/ctds/ctds.htm for details

Note 1: < Usual laugh follows>
Note 2: Usual disclaimers apply

In reply to chris tan:

How much are you selling them for? I'd patent it quick if i were you before petzl get their thieving mitts on the idea

In reply to chris tan:
Remind me again why I climb with you?

In reply to chris tan:

Fantastic!

In reply to chris tan:

The Chris Tan Death Knot is now in regular use by this devoted disciple.

I will investigate the properties of the Chris Tan Reusable Shock Absorber too oh Master.

In reply to Clauso: Sorry I must of missed the chris tan death knot, please enlighten me...

In reply to chris tan:

What is wrong with a via ferratta device for shock loading? surely they are designed for this sort of thing?

BTW, the download is a bit slow, could do with smaller picture sizes in pixels.

In reply to sutty:

Would you fancy carrying a via ferrata thingy in place of every quickdraw on a route?

In reply to chris tan:

Good effort, I greatly admire your inventiveness.

I have no experience of using any sort of friction knot on a sling (friction knot made from a sling yes) so I think I would find it tricky to have confidence in the knot being tight enough when constructing this in situ on a route. I would need to be confident that it was not going to just add to the length of the fall and possibly the impact on my presumably marginal placement. In short I will remember this idea, but I wouldn't use it without testing it, and as I probably won't get around to testing it, I won't be using it.

In reply to chris tan:

Good effort, I have access to a drop test rig so I'll see If I can get round to testing it over the next couple of weeks.

Whats the death knot?

Cheers,

George

In reply to g taylor:
Yes, please re-post the death knot, can't find it...
Sounds intriguing

In reply to Paddy Duncan:

CTDK - To tie into the middle of a rope that was used as doubles by a leader (ie poncy grit routes).

Put the bight down through your usual tie-in point / loop / loops and pull through a couple of meters. Step over this, throw the loop over your head, and pull tight. It's one bit mo-fo of a larksfoot onto your harness

In reply to James Jackson:

Safe as houses - an alpine guide showed me that (seriously).

In reply to James Jackson:

Hmm...
Thank goodness one doesn't have to escape the system too often on a poncy grit route.

In reply to featuresforfeet:
have you tried loading it with failing anchors and some slack in the knot?
t'aint so good then, fine if the knot is tight, even if anchors fail -i.e hanging/weighted belay.

In reply to chris tan:

It's quite difficult to figure out the knots and even the tape/ rope configuration in your pics.
I'm interested in why you would choose tape as a medium for the prussik to slide on? Is it not lot less absorptive than kernmantel rope? Would there not be much higher risk of melting?

Davie

In reply to I am the God of Strathyre:

Chris

I'd have a bad feeling about melting, particularly the prussik, could you replace the prussik with a figure of eight descendeur to take some of the shock out of the load?

Just a thought.

-John

In reply to chris tan:

Chris, put down your brain and step away from the keyboard, you've been thinking again.

Come get your medication.

Phil.

P.S. Wanna try it out tomorrow?

In reply to I am the God of Strathyre:

1. The top know nearest the QD is just a fig 8. That slits the sling into 2 loops.

2. I used a french prussik as the sliding knot.

3. The bottom knot ( optional) is just an overhand. This is used to shorten the length of the slide.


I rigged it out of what I had out at the time. The idea is to be able to improvise this out of what you have at your disposal. A static sling would probably give a better sliding action but I didn't have one handy to test with.


You're going to have to generate a lot of force and slide a long way before the nylon melts. In that case, I suspect the dodgy protection would have popped long before melting occurs.

In reply to Phil West:

Off to MCC, with new lemming. Wanna join us?

In reply to g taylor:

Hi George,

I think my Death Knot is discussed here http://www.ukclimbing.com/forums/t.php?t=141503#1979472 I can't verify as I don't have access to the archives.

Let me know what you find out on the drop test rig. I had to use a selection of prussicks ( different lengths and diameters) and experiment to find the most suitable configuration that will slide at just over body weigth.

In reply to chris tan: Fantastic !

I've just laughed out loud in a Uni library and got stared at by the pretty girl sat next to me - not in a good way.

Do you have any climbing partners or are you a bit of a Mel Gibson in Lethal Weapon kind of a guy?

In reply to chris tan: Hmmmm, been thinking about this one. Looks ok at first thoughts... but does a prussic not grab the rope too quick?

How about a series of concentric loops of bungee, backed up by a full strenght sling?

Whatever happens its good to see someone trying.


Cheers
LD

In reply to Chris Tan ver XLIX:

Hee Hee !

I shall keep an eye out for you in future and run like the wind if i see you on the same crag !!

In reply to Chris Tan ver XLIX:

http://www.urbanrock.com/products_detail.php?CatId=176&PId=1174

Why don't you just buy one of these and live!

In reply to styman:

One big pop and it's gone!

In reply to Chris Tan ver XLIX: but you're still alive!

In reply to chris tan:

Another soloution would be 1 of these

http://www.1st4leisure.co.uk/DB056.jpg

Double up as a bouldering mat!

In reply to styman:

But what if you need to have another go?

In reply to Chris Tan ver XLIX: You are a fiendishly clever man, Mr. Tan! I under-estimated you last time our paths crossed, but you will not be so lucky next time (cue maniacal laughter)

In reply to Chris Tan ver XLIX: use another one

In reply to craig h:

That's a bit like bolting the door after the horse has bolted Craig! Been on the lookout for one of those?

Phil

In reply to chris tan: How about uing one of these. Resetable and you won't kill youself perfecting it... http://www.kong.it/doc408.htm

In reply to mike kann: not seen that before...looks interesting

In reply to chris tan:

One point not yet mentioned is the heat generated when nylon (or whatever) rubs nylon, especially under load.
I know if I fell on a prusik I wouldn't use either bit of gear again, the rope or the loop. The energy of the fall has to go somewhere, and it will be turned to heat. The bigger the force, the bigger the knot slip, the greater the heat.
So I wouldn't like to call it re-usable.

In reply to g taylor: The one at the top is for Via Ferrata and they cost about 12 euro's. You could rig it as a shock absorber for Ice etc. very easily. Its compact and guarunteed to work...

In reply to Phil West:

After last year, yes. Just a bit big to carry to the crags round here!

In reply to Steven Martin:

People are actually taking this seriously, not just as bit of fun?

In reply to beermonkey:

At least half, I would say. And it only needs one to go and use it....

In reply to sutty:

Thanks, for pointing that out. I've resized the images. It should be quicker to download now.

In reply to Steven Martin:

what the system needs is a revision so that the prussik and the prussiked rope are not the climbing rope. Off out to boulder so dont have time to devise and take pictures. But It is possible with the whole arrangement being clibed into via a crab to lead rope.

As to the amount of energy it will absorb yes its going to go into heat and it might be worth doing some calculations as to the specific heat capacity required to weaken the sling/cord for various fall factors. I think the major limmiting factor will be that the prussik will come tight straight away or at the bottom of the captive portion so absorbing little of the energy.

Another thought that occurs to me is that you could probably make something far better with an improvised mini stitcht plate and cord/leash absorber.

I'll give it some thought later when I get back