Mr.Wizard
Reputation
5,594
Next tag badge:
156/100 score
18/20 answers
Badges
13 40
Newest
Impact
~159k people reached

• 19 helpful flags
• 712 votes cast

# 239 Comments

 2d comment Why are eye friction hitches not commonly used in rock climbing? @Benedikt A just-in-case FYI: there is a "figure 9" knot that is supposed to be easy to untie; I've just never actually seen anybody use one. Feb 4 comment Why are eye friction hitches not commonly used in rock climbing? @Chris You can buy them pre-made but bulk cord of the right type can be spliced as well if one has the tools and know-how. Feb 3 comment How to repair the ripped seam in my leather cowboy boots? I'm voting to close this question as off-topic because it does not specifically relate to outdoor activities. Feb 3 comment How to calculate the force (kN) generated by a falling climber onto their protection? It still won't provide a direct answer to this question but for anyone fascinated by such calculations this software appears to be the best on the market: vrigger.com Feb 3 comment How to calculate the force (kN) generated by a falling climber onto their protection? "There is another surprising factor of 2, which is that in the special case where f=0, we get T=2mg, which is a little surprising. You would think that in a factor-zero fall, the rope would just support body weight. But the peak tension is actually more than body weight, because the rope stretches and the person does fall down through some height." Isn't the reason in this equation simply the pulley effect mentioned in the paragraph right before this? "This is because there are two strands pulling down on the pro ..." -- you made it sound like two separate effects. +1 however. Feb 3 comment What to do when you run out of rope on a sports climb? @mattnz I think it is worse than that. If I am remembering my instruction correctly one should never rappel off of soft goods, only hardware, because if while rappelling one strand of rope starts feeding faster than the other the rope can rapidly burn through the sling. I am not qualified to speak authoritatively on this but, again IIRC, my instructor took part in a body recovery that resulted from this malpractice, and that's quite enough to keep me far away from it. Feb 2 comment Why are eye friction hitches not commonly used in rock climbing? @Benedik That's an excellent point. I don't think I've ever seen a figure-9 in the wild however and I am not confident I could check one on sight. Bulin is the same as bowline I am assuming. Feb 2 comment Why are eye friction hitches not commonly used in rock climbing? Re: (4) No, that is what I wanted. A lot of experienced climbers use the rope itself as a personal anchor but I was taught the use of a Purcell because it also has use in rope ascension / self-rescue. Feb 1 comment Why do big wall harnesses have two belay loops? @Dakatine firstascent.co.uk/climb/ocun-quattro-tech-harness.html apparently Feb 1 comment Why are eye friction hitches not commonly used in rock climbing? Thanks for your answer. A few more questions if you please: (1) Would you ask your arborist friend what he uses and why? (fixed tail, split tail, whatever.) (2) Do you have a reference for the use of a single ended Prusik as you describe? I cannot think of a reason for it to fail but at the same time I like to know that things are well tested before using them myself. (3) The "Englaender-Prusik" sounds like what I know as an autoblock; is it? (4) What do you use as a personal anchor? Feb 1 comment Is it ever necessary to double up locking carabiners? I think perhaps I misunderstood your point, or viewpoint. I have top-roped off of O&O non-locking 'biners, and I feel OK about that, but I would not use a single locking carabiner in their place. I do feel that O&O lockers is still more secure, and prefer that setup for something I don't have eyes on, e.g. top-rope anchor. For something I do have eyes on I feel OK with a single beefy locker. I would like to lift my down-vote but I cannot unless someone edits your post and my vote is now locked. Feb 1 comment Is it ever necessary to double up locking carabiners? But two non-locking O&O versus one locking carabiner really isn't the question at hand. Rather, it is if a single locking carabiner always enough, and the answer is no, it is not, IMHO. You wrote "A closed biner has per norm a fully sufficient strength for any force that can be generated in climbing." This is only true ideally, not pragmatically, because of things like crossloading, nose-hooking, inward gate failures, etc. Yes, one can and should try to avoid these things but sometimes an extra level of security is prudent, and from my references I am not the only one to think this. Feb 1 comment Is it ever necessary to double up locking carabiners? Isn't that accidental scenario one of the reasons for opposite-and-opposed carabiners in the first place? Nevertheless it wouldn't necessarily have to be rock; I suppose the rope getting bound up in a funny way could produce inward pressure, kind of like back-clipping. If you could be sure that a carabiner would never be loaded oddly or pressed against anything then might not one use a single non-locking carabiner? That being recognized as unsafe implies that odd loadings should be provided for. (continued) Feb 1 comment What to do if the second seems stuck and absolutely no communication is possible? @BenCrowell I would love to hear the specifics of that harrowing experience. Feb 1 comment Why are these acceptable and safe anchors? @Felix Good point! If someone has been top-roping and lowering off the ring directly all bets are off. Feb 1 comment Why do Sandpipers sometimes hop on one leg? Do you have any references for this statement? Feb 1 comment Is it ever necessary to double up locking carabiners? Locking carabiners are not nearly as secure as you seem to think. The inward gate strength of standard sport-grade lockers a fraction of the already reduced crossload strength, meaning they can quite plausibly be forced open from pressure against a rock, and then you are down to the open gate rating at best. Sorry, but -1 from me. :-( Feb 1 comment Climbing with one arm: any advice on belay systems for beginners (who can only use one arm)? For what it's worth I believe the GriGri is always marketed as an assisted-locking belay device, acknowledging the possibility of failure to auto-lock. Some people do use a GriGri for rope soloing but the practice is generally discouraged from what I can tell, even in the already fringe rope soloing circles. I don't have a better suggestion but I feel that this risk should at least be acknowledged in your answer. Feb 1 comment Is it ever necessary to double up locking carabiners? @DudeOnRock Thank you. :-) Jan 31 comment What is the correct way to attach a rope to a harness with carabiners? Possible duplicate: (4052)