UKC

Does anyone know where I can get a single 60m strand of dyneema, somewhere between 5.5 and 6.5mm in diameter?
I called Beal, but the longest lengths of their 5.5 dyneema is 50m
Any advice gratefully received. I need it for an ab pull-cord.
Tom

In reply to Tom Chamberlain:

Does it have to be Dyneema? You can get a good variety of small-diameter ropes/cords which would probably be suitable and easily available in 60+m.

Have a look at http://www.flints.co.uk/acatalog/Fibre_Ropes_and_Monofilament_Line.html

In reply to Tom Chamberlain: Do you really need an ab pull-cord to be rated at 15kN?

Several points.
First, it will cost far more than 6mm accessory cord.
Second, it will probably handle worse than 6mm accessory cord.
Third, it will probably weigh the same as 6mm accessory cord
although
Fourth, on the plus side, it will stretch much less than 6mm accessory cord.

I've used standard 6mm cord for retrievable abseils in the Alps before and it worked fine although I am still slightly on the fence and about the whole technique.

FWIW Needlesport sell 5.5mm Marlow Dyneema cord by the metre (http://www.needlesports.com/Catalogue/Rock-Climbing-Equipment/Cord-Tape/Cor... ) so I'd suggest speaking them or contacting Marlow direct http://www.marlowropes.com/

In reply to Tom Chamberlain:

A few years back now ('06?) I got 55m of Millet dyneema 5mm (6mm?) from Telemark-Pyrenees.com

I think it comes in 100m rolls or something. It was a bit of a faff, but doable.

55m was to match the stretch of the 50m x 9mm rope.

In reply to Tom Chamberlain: it is likely to be stiff and hard to handle. Normal cord is likely to be better, and cheaper.

In reply to The Ex-Engineer:



Did you find it saved any weight? I was looking at this a while back, but couldn't really see where the weight saving was compared to twin ropes. Or is it more for using on easyish routes, where one 1/2 rope is fine, but there are still a few abseils? If you were going to use dyneema, then you could buy a pair of twins for not much more than the price of the cord alone!

In reply to Markel:

I always thought that this was more to do with being able to use a single rope for the route, thus saving faff, with the retrieval cord being to allow long abs. So a retrival cord is lighter than a half rope rather than the whole system being lighter.

In reply to Monk:

That would make more sense, but I guess if you went really thin i.e. 3-4mm then you could really cut down on weight.

In reply to Markel: The whole thing is really complicated and it is very hard to generalise as it doesn't just come down to saving weight.

For most route I don't think it really works but I can certainly imagine the occasional exception.

As you suggest, there are some easier routes where it might make sense, however, it is more likely to come into its own is on much harder routes where there is aid involved or the second is likely to need to jumar at some point for reasons of speed. I would certainly not like to have to jumar on twins.

I've not used this system yet but have thought about it quite a lot and am quite keen to use it on a couple of routes.

The reasons for using aren't just to safe weight. It is more about faff and time.

Take the Walker Spur for example.

If i were climbing this the rope work would be quicker and more straight forward with a single and a load of slings to extend runners.

I also find it is a lot easier to switch to and from moving together with a single.

2 ropes aren't needed for the descent and I wouldn't be planning on abseiling off. However if I did have to abseil off having 55m of thin rope, so I could make full length abseils, would make my life a lot easier.

The other example is the Peutry Ridge Integral. You only really need two ropes for the abseils on the second day. (I would be half tempted to take an old half with me and dump it in a crevasse at the bottom of the abseils, but I know that is naughty!) Again 55m of 6mm would come in handy.

To the OP: If I was going to buy a thin tag rope I would buy 65m (assuming you are using a 60m rope) of Mammut pro cord. It seems much more durable than normal prussik.

HTH

In reply to The Ex-Engineer:

Ok, I think I see what you are getting at. Cheers.

In reply to Tom Ripley: another reason for using a single is so one can use a minitraxion to remove some of the belays.

In reply to Tom Chamberlain: Beal do a 60m 7mm trail line that works great. best not to go too thin as it can tangle easy.

In reply to Tom Chamberlain:

I've not been comfortable with it because of the implications should the rope get stuck when being pulled down. If that happens, then you don't have enough decent weight rope to get yourself out of trouble.

The Verdon Gorge is a prime candidate for using a single rope and abbing in with a tag line, but those little bushes hang onto ropes as if it were their sole purpose in life.

But, if you are planning on doing a route where a single rope will suit, and don't plan on abbing down, then as a lightweight back-up plan, it's got much to recommend it. However, it is not unusual for drama to beget greater drama, and if your single rope gets damaged, life may start to get interesting.

In reply to Tom Chamberlain:

I have never really understood the idea of leading on a single rope then carrying another rope around in order to be able to pull the single rope down if you have to abseil. Saw it quite frequently in the states a couple of years ago. I asked one american about this and he explained the aproach in terms of half ropes being too complicated to use! (He had 60m of 9mm rope strapped to his back as a retrieve line for the abseil off).

The disadvantages I can see include:

A double rope is much easier to use to protect complex routes for both members of the party and you don't have to carry a pile of long slings to extend all of the runners to avoid them lifting in the event of a fall.

With a single rope in the event of damage to the lead rope you are likely to have less options in terms of salvaging enough lead rope to get yourself out of the mess you find yourselves in.

If you wish you can use half ropes in twin rope mode (i.e. clip both into each protection point - I know there are some issues with leverage on karabiners in this situation). You can't magically split a single rope into two half ropes if things get complex.

You can save weight and make splitting the gear to carry easier with half ropes. A typical 10mm rope wieghs in the mid 60's g/metre eg Galaxy at 66g/m; therefore a 60m rope will weigh just under 4Kg. The retrieve line (let us assume 6mm at 23g/m) will weigh 1.5Kg. Total weight 5.5Kg. A pair of 60m mammut Phoenix will weigh only 4.92Kg. However it will cost you about £60 more for the two half ropes.

IF you are scrambling either up to a route or off from the top of a route then each climber has a lead climbing rope which could be used to top rope the other if necessary, I wouldn't fancy being top roped on a static 6mm line.

With ropes it is "horses for courses", single rope climbing is great for direct lines (such as Yosemite Cracks) and sport routes (where the protection cannot be lifted out by the rope (you hope!) but half rope techniques developed for a reason, because they are best suited to the complexities of routes that you find in the UK on larger crags (would you ab down to do Red Wall on Gogarth with a single 10mm rope plus a 6mm rap line?) or in the Alps.

Long live half rope techniques!

In reply to Trevor Langhorne: 4

Ditto to what you said, plus having two climbing ropes means that you have a bit of redundancy - if one gets damaged or you have to cut it after a stuck rope when pulling down an abseil, you still have something to get you off the mountain, which can be appreciable!

no one has mentioned yet that you can use the 2nd line to haul a smallish haul bag - that seems reason #1 for choosing the single+trail line system in the alps
(long MP where a bivy is likely, really hard sport MP when the second wants to freeclimb rather than jumar, etc)

for that use most people choose the beal trail line...