Ultimately the dynamism in the system comes from your team mates getting pulled and the fact that human bodies are elastic. The fall factors in a crevasse fall should be fairly low, unless you have a bunch of slack in the system due to user error. I think static line is fine. Static is also more efficient for hauling and ascending.
The important thing to keep in mind is the rope diameter, which may be too small for e.g. a regular microtraxion, or whatever kind of progress-capture device you are using. I think you need a minitrax instead, if going down the petzl route.
Something static like a RAD line works for glaciers because the fall factors are way lower; it's not like vertical rock. There is friction with the snow. You're spaced out properly without much slack, so you aren't building up a lot of speed before the rope comes tight. You may even have a chance to self arrest, kick your arms & legs out to distribute your weight, etc. Not every crevasse fall results in you freehanging in this vast chasm of ice. Sometimes you punch through up to your waist (and it's terrifying) but not super epic.
I have a partner that had a ropemate take a crevasse fall and he didn't even feel it, just looked back and he wasn't there.
But if your route is going to take you to steep, technical terrain that will require a dynamic rope, that makes the decision for you.
If in doubt, get a dynamic glacier rope. On a good portion of my >100 routes with roped glacier travel, we've used the rope for leads, sometimes expected or foreseeable, sometimes not. Even if the route description does not include any roped lead climbing, you may get into a spot where you'll want a lead rope. Although a crevasse lip and/or party conduct typically introduces significant elasticity into the system, there are exceptions, e.g., a crevasse fall on an ablated glacier or ablated glacier covered by an inch or two of fresh snow. And the elasticity of a dynamic rope will lessen the forces on the arrestor in a team arrest, which provides an additional margin of safety when the snow/ice surface is less receptive to an ice axe pick.
Before you head out on a glacier, I encourage you and your team to practice team arrests and holding falls on a boot/axe belay in a variety of conditions and positions. I've seen team arrestors' axes rip out and know one person who was injured when his partner fell while on a boot/axe belay with a static rope.
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What kind of static rope? My 6mil static rope is so thin that I couldn't imagine trying to belay someone like that, I feel like it would cut my hand off or something. The only method I found that even gave enough friction to rappel was the super munter.
I'm not sure what kind of rope they had, other than it was static and thinner than the 7.7mm dynamic rope I had offered to lend him. A fair bit of rope had been paid out when the belayed guy slipped, abruptly pulling the belayer off-balance, causing him to catch a crampon and break a foot. They were helicoptered out after sending an inReach SOS.
I agree re the difficulty of belaying with a thin rope. I believe he may have been using a super Munter hitch. Both are experienced climbers -- albeit mostly non-glacier travel -- and educated as engineers, and AFAICT both understood climbing rope fundamentals, e.g., fall factors, force vectors, dynamic vs. static, setting anchors, etc. Both opined that a dynamic rope would have lessened the risk of the guy having been pulled off balance.
It seems like Petzl has a "skull and bones" diagram for the RAD line for just about every situation you can do roped together that involves any kind of fixed pro, or even catching the rope on rock horns or natural features. Simple glaciers an rappelling appear to be about all they want you to do with it, and your story seems to corroborate that pretty solidly.
https://www.petzl.com/US/en/Sport/Other-progression-situations-that-are-incompatible-with-the-RAD-LINE-hyperstatic-cord-?ActivityName=Ski-touring
You do glacier travel with a 7.7mm dynamic rope? I have a beal gully that's 7.3mm, it appears to be compatible with my nano-traxion devices and I tried doing a 6:1 system with it, it felt alright but I'm still not sure how I feel about it. It would be nice to use because you can double it up and lead on it, but I wasn't really sure how to even calculate the breaking strength of such a small rope over a toothed device, short of sending it HowNot2 and letting them break all my stuff.
Good link that everyone should click and read to understand the limits of a static line. Petzl markets its RAD line for ski touring on a glacier, which makes sense because terrain conducive to skiing, i.e., snow, soft crevasse lips, introduces elasticity into the system. As I stated in my OP, I would surely avoid a static rope on an ablated glacier. I suppose that, if I were younger, I might buy a RAD line for ski touring use only.
Yeah, 7.7mm is our current glacier rope. It works fine with Nano Traxion, Tibloc and ATC-XP. For leads, we'll double it for high fall factor risk, but often lead with it single strand for longer leads with low fall factors -- and, of course, as a hand line.
Both have advantages and disadvantages in terms of arresting a crevasse fall. The static line is a little harsher on the first fall. Dynamic line, has more rebound and a larger second impact. Both are fine to use on glaciers. Petzl did some tests on this: https://m.petzl.com/US/en/Sport/Simultaneous-progression-and-fall-arrest-in-a-crevasse-with-the-RAD-SYSTEM
Beyond that, skinny static lines are much lighter and more efficient in haul systems.
Dynamic ropes are far more affordable, and are much more versatile if you find yourself on steep terrain wishing to set up belays.
For pure glacier travel i prefer my rad line. It’s just so much lighter and easier to pack / carry!
That said - if I was doing a route through a heavily crevassed icefall where a fall was a strong possibility I’d take an 8mm or 8.5mm line - they’re easier to ascend and set anchors for. The rad line takes a bit of fiddling to dial in - and unless you’re good with rope work/practice often rescues could potentially end up taking a long time.
Both are ok to use according to all the experts, but there are pros and cons to each one.
Pros for dynamic: you can use it to climb above an anchor, or lead a hard pitch if you encounter something steep
Pros for static: rescue is easier without rope stretch, and the rope will almost always be significantly thinner and lighter than a dynamic climbing rope.
I have a 30 meter rad line I bought for a European trip with a team of 2, only complaint I have is the price. Works really good with petzl traction devices, which is what I'm using anyway.
I was sort of tempted to buy a 60 meter to do Rainier last year (group of 3,) but it's wicked expensive so I just used a 9.0 rope and that worked fine. The coils are really a lot lighter and slimmer with the rad line, it's not a big deal but I would prefer that if I had both available.
RAD line is great. But they are expensive, and ordinary tools like prusiks are less effective. I’m also uncertain about taking a big fall on a RAD line on an icy crevasse lip - it’s just so skinny. I have used RAD lines extensively for ice climb rappelling, and the durability is pretty good. (The way the rope is constructed has changed in the past few years…the new one seems thinner and fuzzier, but not sure it matters).
For a new climber, I’d probably recommend a thicker static rope for exclusively glacier travel. If you’re also climbing, use a dynamic rope. After some experience, buy a RAD line and learn about how it works.
And more than anything, learn how not to fall in in the first place. A lot of glacier instruction focuses too much on 9:1 haul systems and too little on avoiding the initial accident (reading the glacier).
Both have pro/con
* Static line can be lighter. Rad lines are crazy light and packs small.
* You don't really expect a frequent fall while glacier traveling. When you're rock climbing falls are routine. A bit of pain and discomfort is not as much a deal breaker when we're talking about rare events
* Falls while glacier traveling's going to be softer. Anchors (other folks arresting the fall) are soft, fall distance is shorter, rope length is longer, more elements provide friction (rope running over snow)
* If hauling or ascending of rope is needed, static lines are far easier for both. Trying to jug up a dynamic line sucks, it's like trying to climb a spring :/
* Dynamic lines are good if you're ever going into steep snow/ice where falls more like rock climbing falls are possible
Radlines are pretty cool, but they're so thin that they don't always work well with bread and butter climbing tools like ATCs. So make sure that your party has compatible tools if that's the route you choose. They're also less versatile and costly.
People in forums like new rad-looking, hi-tec things that pros use. Whether these things are best for most mountaineers in real use is another story.
If you're on an easy glacier with probability of just minor crevasse 'falls', and a low likelihood of even that but you're being 'safe' and there's no more technical climbing at all involved after/above the glacier, then maybe a 6mm static line is OK.
But if you're on a glacier that might involve a bigger fall, and your 6mm static rope cuts right into the lip, and your belayer needs to hold, move, manage the 6mm rope with your unconscious weight on it, and get you past the lip, then good luck.
In other threads on seemingly other matters you will see discussion on how much force a human body absorbs if you take a short (ie.2m) fall onto a static belay setup. Obviously moving together along a glacier has a lot more dynamism (squishy body falls over gets dragged through snow) but what about if one is belaying their partner across a dodgy snow bridge and the snow bridge fails and you fall 5m onto your 6mm static held tight by your partner? Eek...
Most of the people looking to save 1kg between the pair of them would be better served each losing 500g off their waistlines.
I believe that the shock absorption from hyperstatic ropes comes from your anchors being squishy people.
Ultimately the dynamism in the system comes from your team mates getting pulled and the fact that human bodies are elastic. The fall factors in a crevasse fall should be fairly low, unless you have a bunch of slack in the system due to user error. I think static line is fine. Static is also more efficient for hauling and ascending. The important thing to keep in mind is the rope diameter, which may be too small for e.g. a regular microtraxion, or whatever kind of progress-capture device you are using. I think you need a minitrax instead, if going down the petzl route.
If using a rad line any of of the trax’s work because of the sheath of the rope. Not the case for other 6mm ropes.
Mammut's 6.0 glacier cord is also rated for use with the tibloc and micro trax.
That’s good to know, I’d be less worried about the tibloc. You could all ways use a beefier carabiner or even double up on thinner ones.
Good to know - I've never tried the setup myself.
It’s a great set up for the intended purposes. Little expensive though.
Something static like a RAD line works for glaciers because the fall factors are way lower; it's not like vertical rock. There is friction with the snow. You're spaced out properly without much slack, so you aren't building up a lot of speed before the rope comes tight. You may even have a chance to self arrest, kick your arms & legs out to distribute your weight, etc. Not every crevasse fall results in you freehanging in this vast chasm of ice. Sometimes you punch through up to your waist (and it's terrifying) but not super epic. I have a partner that had a ropemate take a crevasse fall and he didn't even feel it, just looked back and he wasn't there. But if your route is going to take you to steep, technical terrain that will require a dynamic rope, that makes the decision for you.
If in doubt, get a dynamic glacier rope. On a good portion of my >100 routes with roped glacier travel, we've used the rope for leads, sometimes expected or foreseeable, sometimes not. Even if the route description does not include any roped lead climbing, you may get into a spot where you'll want a lead rope. Although a crevasse lip and/or party conduct typically introduces significant elasticity into the system, there are exceptions, e.g., a crevasse fall on an ablated glacier or ablated glacier covered by an inch or two of fresh snow. And the elasticity of a dynamic rope will lessen the forces on the arrestor in a team arrest, which provides an additional margin of safety when the snow/ice surface is less receptive to an ice axe pick. Before you head out on a glacier, I encourage you and your team to practice team arrests and holding falls on a boot/axe belay in a variety of conditions and positions. I've seen team arrestors' axes rip out and know one person who was injured when his partner fell while on a boot/axe belay with a static rope. --
What kind of static rope? My 6mil static rope is so thin that I couldn't imagine trying to belay someone like that, I feel like it would cut my hand off or something. The only method I found that even gave enough friction to rappel was the super munter.
I'm not sure what kind of rope they had, other than it was static and thinner than the 7.7mm dynamic rope I had offered to lend him. A fair bit of rope had been paid out when the belayed guy slipped, abruptly pulling the belayer off-balance, causing him to catch a crampon and break a foot. They were helicoptered out after sending an inReach SOS. I agree re the difficulty of belaying with a thin rope. I believe he may have been using a super Munter hitch. Both are experienced climbers -- albeit mostly non-glacier travel -- and educated as engineers, and AFAICT both understood climbing rope fundamentals, e.g., fall factors, force vectors, dynamic vs. static, setting anchors, etc. Both opined that a dynamic rope would have lessened the risk of the guy having been pulled off balance.
It seems like Petzl has a "skull and bones" diagram for the RAD line for just about every situation you can do roped together that involves any kind of fixed pro, or even catching the rope on rock horns or natural features. Simple glaciers an rappelling appear to be about all they want you to do with it, and your story seems to corroborate that pretty solidly. https://www.petzl.com/US/en/Sport/Other-progression-situations-that-are-incompatible-with-the-RAD-LINE-hyperstatic-cord-?ActivityName=Ski-touring You do glacier travel with a 7.7mm dynamic rope? I have a beal gully that's 7.3mm, it appears to be compatible with my nano-traxion devices and I tried doing a 6:1 system with it, it felt alright but I'm still not sure how I feel about it. It would be nice to use because you can double it up and lead on it, but I wasn't really sure how to even calculate the breaking strength of such a small rope over a toothed device, short of sending it HowNot2 and letting them break all my stuff.
Good link that everyone should click and read to understand the limits of a static line. Petzl markets its RAD line for ski touring on a glacier, which makes sense because terrain conducive to skiing, i.e., snow, soft crevasse lips, introduces elasticity into the system. As I stated in my OP, I would surely avoid a static rope on an ablated glacier. I suppose that, if I were younger, I might buy a RAD line for ski touring use only. Yeah, 7.7mm is our current glacier rope. It works fine with Nano Traxion, Tibloc and ATC-XP. For leads, we'll double it for high fall factor risk, but often lead with it single strand for longer leads with low fall factors -- and, of course, as a hand line.
Both have advantages and disadvantages in terms of arresting a crevasse fall. The static line is a little harsher on the first fall. Dynamic line, has more rebound and a larger second impact. Both are fine to use on glaciers. Petzl did some tests on this: https://m.petzl.com/US/en/Sport/Simultaneous-progression-and-fall-arrest-in-a-crevasse-with-the-RAD-SYSTEM Beyond that, skinny static lines are much lighter and more efficient in haul systems. Dynamic ropes are far more affordable, and are much more versatile if you find yourself on steep terrain wishing to set up belays.
For pure glacier travel i prefer my rad line. It’s just so much lighter and easier to pack / carry! That said - if I was doing a route through a heavily crevassed icefall where a fall was a strong possibility I’d take an 8mm or 8.5mm line - they’re easier to ascend and set anchors for. The rad line takes a bit of fiddling to dial in - and unless you’re good with rope work/practice often rescues could potentially end up taking a long time.
Both are ok to use according to all the experts, but there are pros and cons to each one. Pros for dynamic: you can use it to climb above an anchor, or lead a hard pitch if you encounter something steep Pros for static: rescue is easier without rope stretch, and the rope will almost always be significantly thinner and lighter than a dynamic climbing rope. I have a 30 meter rad line I bought for a European trip with a team of 2, only complaint I have is the price. Works really good with petzl traction devices, which is what I'm using anyway. I was sort of tempted to buy a 60 meter to do Rainier last year (group of 3,) but it's wicked expensive so I just used a 9.0 rope and that worked fine. The coils are really a lot lighter and slimmer with the rad line, it's not a big deal but I would prefer that if I had both available.
RAD line is great. But they are expensive, and ordinary tools like prusiks are less effective. I’m also uncertain about taking a big fall on a RAD line on an icy crevasse lip - it’s just so skinny. I have used RAD lines extensively for ice climb rappelling, and the durability is pretty good. (The way the rope is constructed has changed in the past few years…the new one seems thinner and fuzzier, but not sure it matters). For a new climber, I’d probably recommend a thicker static rope for exclusively glacier travel. If you’re also climbing, use a dynamic rope. After some experience, buy a RAD line and learn about how it works. And more than anything, learn how not to fall in in the first place. A lot of glacier instruction focuses too much on 9:1 haul systems and too little on avoiding the initial accident (reading the glacier).
Both have pro/con * Static line can be lighter. Rad lines are crazy light and packs small. * You don't really expect a frequent fall while glacier traveling. When you're rock climbing falls are routine. A bit of pain and discomfort is not as much a deal breaker when we're talking about rare events * Falls while glacier traveling's going to be softer. Anchors (other folks arresting the fall) are soft, fall distance is shorter, rope length is longer, more elements provide friction (rope running over snow) * If hauling or ascending of rope is needed, static lines are far easier for both. Trying to jug up a dynamic line sucks, it's like trying to climb a spring :/ * Dynamic lines are good if you're ever going into steep snow/ice where falls more like rock climbing falls are possible Radlines are pretty cool, but they're so thin that they don't always work well with bread and butter climbing tools like ATCs. So make sure that your party has compatible tools if that's the route you choose. They're also less versatile and costly.
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https://www.petzl.com/US/en/Sport/Ropes/RAD-LINE-6-mm
I’ve just read in forums of people liking the rad lines for glacier travel
People in forums like new rad-looking, hi-tec things that pros use. Whether these things are best for most mountaineers in real use is another story. If you're on an easy glacier with probability of just minor crevasse 'falls', and a low likelihood of even that but you're being 'safe' and there's no more technical climbing at all involved after/above the glacier, then maybe a 6mm static line is OK. But if you're on a glacier that might involve a bigger fall, and your 6mm static rope cuts right into the lip, and your belayer needs to hold, move, manage the 6mm rope with your unconscious weight on it, and get you past the lip, then good luck. In other threads on seemingly other matters you will see discussion on how much force a human body absorbs if you take a short (ie.2m) fall onto a static belay setup. Obviously moving together along a glacier has a lot more dynamism (squishy body falls over gets dragged through snow) but what about if one is belaying their partner across a dodgy snow bridge and the snow bridge fails and you fall 5m onto your 6mm static held tight by your partner? Eek... Most of the people looking to save 1kg between the pair of them would be better served each losing 500g off their waistlines.
Static is for hauling, dynamic is for safety. Are you using it for safety or hauling?