Hi all

I'm about to tackle a drum of new rope.

Given that pre soaking and drying 170m is a bit of a challenge, how do I go about chopping it into lengths?  (OK, I know how to chop it !! I'm taking about ending up with a 70m length, for example, after shrinkage).

I suppose another way to look at it is how precise are the pitch lengths in rigging guides?  If it says 70 and my rope shrinks to 68m am I going to fall off the end?  (or rather get hung up on my terminal knot)?

Any suggestions as to the best combinations of lengths? 

Wouldn't this rather depend on which pitches and how many you are rigging - not to mention what other rope you have?

Anyway, for my money I'd go a 70, a 40 and 2 30's or thereabouts.

Unless of course I was comtemplating rigging an 80m pitch?

And it's a fair bet the 70 will end up a lot less than 68m. So yes, you will likely find yourself flailing about in mid air  :-\

Depending upon what ropes you already have access to & where you intend to use them, I'd try to keep one length as long as you can get away with.

It seems that any group of 3 or 4 regular SRTers will be able to produce enough short to medium lengths (say <45m) to more than cover any trip in the country requiring such lengths but once you get above that the availability of suitable ropes decreases exponentially...

topcat said:

I suppose another way to look at it is how precise are the pitch lengths in rigging guides?  If it says 70 and my rope shrinks to 68m am I going to fall off the end?  (or rather get hung up on my terminal knot)?

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Rigging guides are guides so there will be some leeway in the quoted rope length. After all, two cavers could rig the same pitch and use different knots and leave differing size loops at rebelays, etc. so the rope length used can vary appreciably.

topcat said:

Any suggestions as to the best combinations of lengths? 

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The best combination of lengths depends on the pitches you intend to rig of course. Have a quick flick through the rigging guide f0r the area you most cave in and write down the lengths you would need. Then choose the most used lengths use that to guide you.

Cap'n Chris said:

http://ukcaving.com/board/index.php?topic=11749.0

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Thanks Chris.  I've read all the links and am reassured in so far as I too have  being trawling through rigging guides and tabulating pitch lengths in order to gauge the most useful lengths. [reinventing the wheel ]

So if I add 10% and then cut, then soak, then use I will still be a bit short long term, but maybe not too far out? (Edlerid soft static) ??

tc

We had the same dilemma, we went 80m and 90m

zaphod79 said:

We had the same dilemma, we went 80m and 90m

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If you already have shorter lengths then that is probably good. In the absence of shorter lengths being available then (as above) 70-80 plus a mix of shorter ropes is probably best.

From various "studies" of rigging guides the shorter lengths (15-30) tend to be most common, a 70 or so doesn't crop up often but unless you like mid-pitch knot passes it's always worth having one long rope (in this country at least you're not likely to need multiple long ropes, usually one long with a selection of shorter ones works best).

For me the most important piece of advice is to remember that the rope will continue to shrink over the first 6-12 months of use even when you've pre-shrunk it. So, personally I pre-shrink and then still cut nearly 10% longer than I actually need. That way I will have a usable rope in 2 years' time. The other important thing is what Dunc said - shorter lengths are really important and will get much more use.

So personally I'd pre-shrink (in the bath or a clean wheelie bin) and then cut vaguely as follows:

65m, 44m, 33m, 22m, 11m (or replace the 65m and 11m with a 54m and a second 22m).

Use an old knife heated with a blowtorch or on the gas hob.