crevasse rescue on rope with knots

If a two person team ties arresting knots in their line, what is the best way to set up a haul system?

It seems like it would be very difficult to create a progress capture if the rope has something like butterfly knots tied every few feet. The only thing I can come up with is to set up a 4:1 with the remaining rope. Is there a simpler method?

If it is only a two person team, they should be carrying rescue coils for this exact purpose. You can then drop a loop to the fallen climber and set up a hauling system. The advantage to rescue coils is the lip of the crevasse can be better prepped prior to hauling and allows for flexibility of the rescue. If the fallen climber is unconscious, this system also allows for the other climber to rap down and setup the hauling system then self extricate.

Typically a two-person team must be very skilled in crevasse rescue and be able to rely only on themselves.

Or just call over the guided group that is behind you and have the guide help out...

Take my advice with a grain of salt, as I've never had to do any of this myself. I've always had three people.

ZackB wrote:If it is only a two person team, they should be carrying rescue coils for this exact purpose. You can then drop a loop to the fallen climber and set up a hauling system. The advantage to rescue coils is the lip of the crevasse can be better prepped prior to hauling and allows for flexibility of the rescue. If the fallen climber is unconscious, this system also allows for the other climber to rap down and setup the hauling system then self extricate. Typically a two-person team must be very skilled in crevasse rescue and be able to rely only on themselves. Or just call over the guided group that is behind you and have the guide help out... Take my advice with a grain of salt, as I've never had to do any of this myself. I've always had three people.

Yeah that was what I was thinking. But no way will 2:1 be enough to haul with one person. So setting up a separate haul system means a 4:1, which means a mess of ropes going towards the crevasse, plus the original load line with the knots in it, which sounds like a big cf with lots of gear compared to a z haul on a prussik. I was hoping there was some simpler clever way to do it.

You can actually do the drop loop and then setup a z-pulley on top of that, giving a haul of 6:1 (other combinations possible). The original load strand with the knots is no longer an issue since you are hauling on the drop loop setup. As long as you keep the system organized, it really isn't that messy, or complicated.

Hopefully someone else will chime in with better explanation skills, or pictures. I am moving so all my pictures are packed in some box somewhere.

Edit: looks like there are some pictures on this website: Crevasse Rescue
I believe they are calling what I describe above a "Canadian Drop Loop"

Climbed Rainier as a 2 man team using butterfly knots 2 years ago. We each carried enough extra rope to build a drop loop Z pulley. It's a lot of rope and gear to carry - unless you have a go-pro and want to record your self rescue for Good Morning America.

To answser the OPs question:
- The fallen climber needs to trying ascending the rope. Although not ideal, prussics can be passed around knots in the rope. Mechanical ascenders make it easier.
- If the first knot catches, the rescuer acts normally. Again, prussics and ascenders can be passed around knots. For longer falls, canadian drop loop will likely be the best method.

That being said, has anyone actually done a controlled experiment on this?

It seems like the probability of a knot holding a fall that the "belayer" would not be able to hold is rather small. Is the increased hastle of repeated tying and untying knots and/or ascending a rope with knots in it worth it?

Ascending is easy, you just aid up the loops assuming you tie your butterflies close enough together. It's hauling that is trickier.

Unicorn hitch on a bight

Why use knots? For a 2 man team the knots give the climber who is holding the fall a reasonable chance at building an anchor and being able to transfer the weight on to it. They also help keep a heavier climber from dragging a lighter climber into the crevasse. Self rescue is always the preferred option, but you need to be prepared for a haul if the fallen climber is injured. The drop loop is the "easiest" way to haul when using a knotted rope on a 2 man team.