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9mm or 10mm SRT rope
- Thread starter Oscar D
- Start date
I would use 10.5mm if it is going to get hammered by novices, as it doesn't stretch as much making easier prussiking. For personal use, i would go for 9mm.
I think on the whole 9mm is better as it is usually cheaper, lighter and packs down smaller. I don't think there is much difference in how they wear (i.e. they probably have similar sheath thicknesses, so assuming you bin/cut them if you start to see core).
BW
Can
I think on the whole 9mm is better as it is usually cheaper, lighter and packs down smaller. I don't think there is much difference in how they wear (i.e. they probably have similar sheath thicknesses, so assuming you bin/cut them if you start to see core).
BW
Can
Here are a few thoughts.
Maybe you could start by listing the pros and cons of each:
9 mm
Pros: Lighter, packs into tackle bags more easily, cheaper, easier to climb, absorbs less water
Cons: Less resistant to abrasion if badly rigged or something goes wrong with the rigging, probably less resistant to damage by grit getting in between the fibres, can be a bit scary when ?shiny? and new/dry as descent can be less easy to control (depending on type of descender), knots can be more difficult to untie
10?11 mm: Opposite of above
No doubt others will think of other pros and cons.
My wife and I found that the biggest advantage of 9 mm is that it makes it possible for us to do trips where we?d have struggled to carry the rope ? not so much the weight, more the number of bags needed to carry it ? using 10 mm.
I guess ultimately it?s down to personal preference ? for what it?s worth, most of our rope is 9 mm, but we find that a length of ?chunky? 10?11 mm Marlow is great for places like Lancaster Hole where the rope will almost certainly get covered in mud, which will get ground into it (to some extent).
It?s perhaps also worth considering who?s likely to use your rope ? if you?re confident of your pals? ability, then 9 mm, but if it?s likely to be used (and possibly abused) by novices, then thicker rope might be a better bet. (I posted this as the above was being posted, hence the overlap.)
I notice that Canary states that thicker rope is easier to climb, when I said just the opposite; to clarify what I meant, I find that jammers run more readily on thinner rope (especially when it gets mucky) than on thicker rope, and it's easier to get started, but I accept what Canary says about stretch.
Maybe you could start by listing the pros and cons of each:
9 mm
Pros: Lighter, packs into tackle bags more easily, cheaper, easier to climb, absorbs less water
Cons: Less resistant to abrasion if badly rigged or something goes wrong with the rigging, probably less resistant to damage by grit getting in between the fibres, can be a bit scary when ?shiny? and new/dry as descent can be less easy to control (depending on type of descender), knots can be more difficult to untie
10?11 mm: Opposite of above
No doubt others will think of other pros and cons.
My wife and I found that the biggest advantage of 9 mm is that it makes it possible for us to do trips where we?d have struggled to carry the rope ? not so much the weight, more the number of bags needed to carry it ? using 10 mm.
I guess ultimately it?s down to personal preference ? for what it?s worth, most of our rope is 9 mm, but we find that a length of ?chunky? 10?11 mm Marlow is great for places like Lancaster Hole where the rope will almost certainly get covered in mud, which will get ground into it (to some extent).
It?s perhaps also worth considering who?s likely to use your rope ? if you?re confident of your pals? ability, then 9 mm, but if it?s likely to be used (and possibly abused) by novices, then thicker rope might be a better bet. (I posted this as the above was being posted, hence the overlap.)
I notice that Canary states that thicker rope is easier to climb, when I said just the opposite; to clarify what I meant, I find that jammers run more readily on thinner rope (especially when it gets mucky) than on thicker rope, and it's easier to get started, but I accept what Canary says about stretch.
Thanks all for the advice.Hi OS, if you're buying rope for the first time you need to be aware that when it gets wet and dries out, it can shrink by a fair amount.
If you soak it and allow it to dry it may shrink by anything up to 5 or 6%, but it will continue to shrink with use.
I've just checked some data on our ropes, and the maximum shrinkage I seem to have recorded is 13/2% ? so you'll need to allow for this when cutting it to what you think are appropriate lenghths.
If you soak it and allow it to dry it may shrink by anything up to 5 or 6%, but it will continue to shrink with use.
I've just checked some data on our ropes, and the maximum shrinkage I seem to have recorded is 13/2% ? so you'll need to allow for this when cutting it to what you think are appropriate lenghths.
Leclused
Well-known member
Fulk said:
When my clubs buys rope (on 200m rolls) I ALWAYS dump the rope in the bathtub for a while (approx 2 days) before cutting the rope.
If you cut an unwashed rope and mark the length of it on a label on the rope then you end up with ropes that are shorter then mentioned on the label
This can cause problems when somebody grabs a rope that says 40m but in reality it is only 35m due the shrink.
On average a shrink percentage of 10% is common.
MJenkinson
Active member
I also like to run new rope through a descender as it seems to squeeze a lot of the manufacturing lube (???) out of the rope and can make it a "little" less speedy on descent. I usually then soak it again, dry it and then measure / cut.
Leclused
Well-known member
MJenkinson said:
So the work method would be.
- Soak the rope
- Pull the WET rope through a descender
- Soak again
- Let it dry
- Measure / cut / label the robe
- ... go caving ....
I think I'm going to take over the pull through descender step the next time a new roll comes in.
Simon Wilson
New member
Ian Ball said:
I put new rope in the washing machine. A long cool wash, no detergent, no spin.
If you get a 200m reel it won't fit in without cramming it in. To get it in loose cut it into half and do two washes.
Allowing for 10% eventual shrinkage you will end up with two ropes around 90m which is neat to cut into 60 + 30 and 50 + 40.
andrewmcleod
Well-known member
I cut ropes based on 10-15% shrinkage from the dry rope - so I measure it before I soak it. It might shrink 5% when you soak it after purchase but it can easily shrink more in use, so even if you soak then measure you should still leave a bit spare.
I wouldn't want Class A 9mm rope - to make it class A it has to withstand more force in a drop test so it is likely to have more core and less sheath, while I want more sheath for abrasion and the rope is plenty strong enough.
I wouldn't want Class A 9mm rope - to make it class A it has to withstand more force in a drop test so it is likely to have more core and less sheath, while I want more sheath for abrasion and the rope is plenty strong enough.
andrewmc:
These are interesting points you make, Andrew; can you back up your ideas with any real evidence? Of all the rope types we have, my favourite is 9 mm Gleistein, which is Class A (mind you, it looks quite thick for 9 mm, and certainly appears to be thicker than our red Beal 9 mm).
These are interesting points you make, Andrew; can you back up your ideas with any real evidence? Of all the rope types we have, my favourite is 9 mm Gleistein, which is Class A (mind you, it looks quite thick for 9 mm, and certainly appears to be thicker than our red Beal 9 mm).
