ExcitableBoy wrote:Wastral wrote: There is no difference between 3 man and 2 man crevasse rescue technique. None.
I gotta disagree on this one. With a three man team, it is possible to raise a victim with a z haul, but a single climber raising another climber with just a z system is highly unlikely. The man on top will need a greater mechanical advantage, thus the need for the Z x C.
I am going to describe why I don't believe a Z x C would ever be used in a 2 man team. I personally have never used it. When situations warranted more I made a 4:1, 6:1, 8:1 with pullies from myself and my partner as this required going DOWN into the hole and checking them, at which time one can grab their pullies as well and now one has tons of pullies.
Ok onto my description.
A 2 man team cannot use the Z X C unless one can drop a loop into the hole. Probably won't have enough line anyways to do so.
IF the guy in the hole is not completely stuck where he cannot get his prussics out and climb out himself, the likelyhood of getting a drop loop and hooked up is 0 or near 0 as well. Even a guy with one injured leg/arm can still self extract themselves far quicker than a single person hauling up top. I have never seen when this is NOT the case, even under the circumstances of a deeply incised lip.
Z x C only works when the guy is barely in. In which case its far quicker for the guy in the hole to prussic up to either the lip, cut in lip, or new line dangling down at which time they switch ropes and get their own ass out of the hole far quicker than setting up a pulley system. Not to mention they stay warm.
z haul is 3:1, adding a C gets 6:1. A single guy can generally raise another single guy on a Z unless one is a completly out of shape wimp. Everyone can squat/leg press double their body weight. Average guy half in shape can squat 400lbs all day long. 400lbs x 3 divided by pulley efficiency gets around 800lbs of force when all is said and done subtract friction drops it to around 400lbs @@@ the climber! If you need more than this, something is WRONG and you are probably killing your partner under a lip! Gets back to why I am dumbfounded when everyone seems to pull with their back and arms in a crevasse rescue situation! Gets them less than
HALF OF WHAT THEY CAN GET WITH THEIR LEGS!If one needs more force than this
something is seriously wrong and you are probably pulling your buddy in half. If your buddy is injured and you really do have to get more mechanical advantage because the guy is inert, then you have to
get your butt into the hole and administer first aid first and grab their pullies etc 2nd. At which time a ZxC isn't desired either as a straight up 4:1, 6:1, or 8:1 is preferred as this
leaves a line available to descend down yourself, or switch your buddy over onto that new line because of lip cut in!!!
Yes, a 2 person team should know how to build a Z x C, but it will probably never be used as there are far quicker/simpler ways to get someone out of a hole or the situation determines a far more complicated way entirely. Either straight Z with guy in hole helping, or dangling, or straight, C without the Z, or none at all allowing the top guy to take pics of his beffudled friend prussicing out.
IF I have stated something in error here please let me know. I am always willing to learn a better way. From all the different situations I have practiced, the above fits with what I and my climbing friends have found to be true for 2 and more person teams in all situations. True, I haven't had many crevasse fall ins. Only 1 had a serious lip and the guy who fell in simply prussiced out in under 5 minutes after the anchor was made. The other times were all practice.
PS. Regarding 2 in the hole on 3 man team, you have to descend and grab their gear and also hope person nearest you can switch lines and prussic out. In either case unless you are very close together the 1st person won't have enough rope to drop a C into the hole in the first place.