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Mar
5
revised Why are people so worried about Giardia?
added 213 characters in body
Mar
5
revised Why are people so worried about Giardia?
added 22 characters in body
Mar
5
comment Why are people so worried about Giardia?
@ChrisMendez: Because it totally sucks and ruins your trip (1) Most Giardia infections produce no symptoms. (2) Evidence shows that you can't get it from backcountry water in the US. (3) It has an incubation period of about a week or two, so even if you did manage to catch it while backpacking, it wouldn't be able to ruin your trip unless it was quite a long trip.
Mar
5
revised Why are people so worried about Giardia?
added 16 characters in body
Mar
5
answered Why are people so worried about Giardia?
Mar
3
comment How much should your backpack weigh?
@Tullochgorum: What are "the tables?" Your numbers are simply not possible. 6000 calories is a vast amount of food. A normal human eats about 2000 calories per day, so 6000 calories would be like eating 9 normal meals per day rather than 3.
Mar
3
comment How much should your backpack weigh?
@Mr.Wizard: backpackinglight.com/cgi-bin/backpackinglight/forums/… backpackinglight.com/cgi-bin/backpackinglight/forums/…
Mar
3
comment What do I do if I lose my belay plate?
Isn't this just a shorter duplicate of my answer?
Mar
3
comment When is it appropriate to make a cairn?
@tsturzl: LNT states to travel on steady ground, its best to stay on trail, and a cairn will help you do that. I think it's more complicated than that. For one thing, there may be no trail. On a cross-country route that has no trail but that is used by quite a few people, the landscape may actually be less damaged if different people take different routes, so that no track is formed.
Mar
3
comment How much should your backpack weigh?
Most of this answer is pretty good, but something is wrong here: If you're a medium sized guy on a tough walk you'll be burning 5000-6000 calories a day. On short trips you can undereat, but on longer trips you should be budgeting around 1 kilo per day for food. Experience shows that a 70 kg person eats about 2700 calories a day on a backpacking trip. (For long-distance through-hikers, this goes up to about 3800 calories/day.) This is based on online polls and experience of professional guides. For typical foods, 2700 cal is about 700 g.
Mar
3
comment How much should your backpack weigh?
It's fairly easy, with modern gear, to be around one third to one quarter of your body weight, including food, water, and camera. This is far too much. For a one-week trip without resupply, I would carry about 1/6 of my body weight. For a weekend trip, about 1/10. it's a bit dangerous to drink their poo run-off (giardia sucks) This is a myth. lightandmatter.com/article/hiking_water.html
Mar
2
comment How to use a Munter hitch to belay and rappel?
Interesting link, thanks. Based on that, I'd suggest deleting the sentence in your answer that we've been discussing.
Mar
2
awarded  Nice Question
Mar
2
comment How to use a Munter hitch to belay and rappel?
Nice answer. But: having the load strand closest to the spine takes full advantage of the strength of the carabiner This doesn't make much sense to me physically. Unless there is test data to support it, I would not believe this claim.
Mar
2
comment How to use a Munter hitch to belay and rappel?
Yes, I agree that it's physically plausible. We expect tension to go like exp(mu theta) as a rope is wrapped around a cylinder, so here we should get an extra factor of exp(pi mu). The nylon sheath of a climbing rope on an aluminum carabiner probably has mu of approximately 0.15. (It's not easy to measure accurately or reproducibly.) This gives exp(pi mu)~1.6, which seems roughly consistent with the diagram from FotH claiming 4/3, as well as with requiem's data. (A mu of 0.1 reproduces those numbers better.)
Mar
2
comment How to use a Munter hitch to belay and rappel?
there is a slight strength difference between spine and gate sides (and in my experience there is a big difference) I don't understand. First you say it's slight, and then you say it's big? What is the experience that tells you there's a big difference? Have you broken a carabiner? There is a difference in strength between cross-loading a carabiner and loading it properly. I don't believe it makes any difference in strength whether you flip the orientation of the biner about its long axis. In both cases, the spine and the gate side are each holding half the load (or the biner would rotate).
Mar
2
comment How to use a Munter hitch to belay and rappel?
isn't downwards the least amount of friction? You're a mathematician, right? You might enjoy this: lightandmatter.com/article/knots.html . The basic idea is that in this type of knot, there is a force that you apply on the brake strand, and the knot amplifies that force by some factor. According to FotH, the amplification factor shows a small amount of variation (25%) depending on the direction in which you hold the brake strand. But for all directions, the amplification is so huge that if you're rappelling, you can easily stop your rappel by applying a small force.
Mar
2
comment When is it appropriate to make a cairn?
IMO far more cairns get built than should be built. I knock down a lot of them, because they alter the landscape unnecessarily. This is probably related to the fact that so many people have poor map reading skills, and so little experience with off-trail travel, so that they need constant reassurance.
Mar
2
comment How to use a Munter hitch to belay and rappel?
I have had it confirmed by three professional instructors (two in person, one in a video online) that 0 degrees is the strongest braking position. Of course that's not actually an independent confirmation, because they're probably all getting their information from Freedom of the Hills.
Mar
2
comment How to use a Munter hitch to belay and rappel?
The fact that people use an autoblock when rappelling with a Munter does not mean that downward is the strongest braking position. The figure from FotH reproduced in DudeOnRock's answer claims that you still get 75% of the maximum braking force in this position. You don't want or need 100% of the braking force when you're rappelling. 100% of the braking force is enough to catch a hard lead fall, which is many times greater than what is needed in order to stop your rappell and hold body weight.