Best rope dia for glacier - trade off of weight vs rescue?

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Best rope dia for glacier - trade off of weight vs rescue?

by CoA » Tue May 29, 2018 3:14 am

Hey folks, going back through some older posts here it seems that a half rope is a favored option for glacier travel. There seem to be some differing opinions of whether it’s better to go lighter and thinner (in the range 7 - 8mm), or slightly thicker (8.5-9mm). Obviously a thinner rope reduces weight but my understanding is that it makes rescue and belay tasks more difficult.

I’m looking at ropes like the Black Diamond Dry 7.9 (39 g/m) and 8.5 (46 g/m) in a 60m length so it’s possible to use for rappelling too. Obviously the 7.9 is a decent weight saving in that length, but not sure if it’s worth the trade-off for sacrificing some functionality in rescue scenarios etc.

Any thoughts (or suggestions of other ropes I should be looking at) are welcome.

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Re: Best rope dia for glacier - trade off of weight vs rescu

by ExcitableBoy » Fri Jun 01, 2018 3:06 pm

My $0.02 cents, go with a 50 meter half rope. I find 8.5 mm to be a perfect balance of light weight and ability to haul and ascend. 60 meters is unnecessary extra weight, and a 60 meter 7.9 mm weighs about the same as a 50 meter 8.5mm rope depending upon the manufacturer.

Anyone advocating using a skinnier than 8 mm rope likely has never had to ascend or haul on one. Too much stretch, more difficult to get Prussik cords to 'bite', too hard to grasp while hauling.

Manufactures are allowed 0.2 mm of fudge factor, so that 7.9 could actually be an 8.1. When comparing ropes, look at the weight in grams/meter rather than diameter. They can't fudge the weight.

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Re: Best rope dia for glacier - trade off of weight vs rescu

by OPHIRTODD » Sun Jun 17, 2018 6:19 pm

A couple more cents -

If you are ONLY using the rope for glacier travel, you might want to research "low-stretch" ropes. These are different than static lines, but have much lower elongation factors than a skinny, dynamic climbing rope. They have been the choice of some of the Denali guide services for years. You'll probably not end up as deep in most crevasse falls (less chance for hitting something as you go past) and they are way easier when used to execute a rope rescue.

I agree with Excitable Boy about the diameters and generally about the length - 50m is a good all-around length.

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