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bio website lightandmatter.com
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visits member for 2 years
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I live in LA and enjoy day hikes, backpacking, rock climbing, and mountaineering.


Mar
27
comment How do you build a campfire that leaves no trace?
Are you assuming you can obtain firewood without disturbing the environment, e.g., you're car camping and have brought in firewood in the car? If you're in the backcountry, then you're going to have to gather wood, and that's not going to be LNT.
Mar
26
comment How to calculate the force (kN) generated by a falling climber onto their protection?
The answer seems to suggest that the online calculator implements the analysis given in the WP article. Actually, reading the javascript source code of the calculator shows that it calculates S=(m/m0)fk, where they call S the "shock force," m is the mass of the climber, m0=80 kg, f is the fall factor, and k is 4.5 for a dynamic rope, 9 for a static rope. This is completely different from the WP result. In particular, it doesn't make sense in the case where f=0. This is the case where the rope is simply holding the climber's body weight, and in this case there is not zero tension in the rope.
Mar
25
comment Lowering a climber from above using a belay device in autolocking mode
We had access to the top of the climb by scrambling up the back.
Mar
24
comment Lowering a climber from above using a belay device in autolocking mode
I don't think the BMC video is really relevant here. The question is specifically about an autoblocking device and about lowering. The video shows a non-autoblocking device (looks like an ordinary ATC) and doesn't deal with lowering.
Mar
24
comment Lowering a climber from above using a belay device in autolocking mode
Thanks, that's all very helpful. In my case the reason for belaying from above was that the climb was too long for top-roping with a single rope. I see what you mean about the Munter. I guess the question would be what mode of failure the Munter is supposed to be guarding against. I'll edit the question in order to try to clarify this.
Mar
24
comment Using a synthetic sleeping bag on/under it's limit
You could just wear a lot of clothes to bed, including thick wool long underwear and a wool cap.
Mar
18
comment Camping with a tarp, what are risks about animals?
I've never camped in any place where there was any issue with small animals or snakes wanting to crawl into my sleeping bag or anything like that. Small-animal nuisances are usually about them wanting your food, and a tent doesn't help with that. Reptiles are normally not very active at night, and most are shy.
Mar
16
comment How do I find known and documented trails for trail running in New England?
Openstreetmap often shows trails that you can't find out about anywhere else online.
Mar
15
comment Do polarized sunglasses protect against snow blindess?
The question is asking about snow blindness, which is a specific, severe medical problem. It's not just a matter of having your eyes take time to adjust to lower light levels.
Mar
11
comment How to top belay 2 climbers at the same time on multi-pitch climb?
I think I understand you now. I'm going to edit the first paragraph. If you don't like my edit, feel free to roll it back.
Mar
10
comment How to top belay 2 climbers at the same time on multi-pitch climb?
As Raz Peel's answer explains, it is certainly possible to set up a belay with a standard ATC to be auto-blocking. However, one of the design features of the ATC guide is that it makes it easier to get the auto-blocking. My understanding is that the name of the ATC guide refers specifically to the fact that guides may frequently find themselves in a situation where they need to belay two clients at once. The autoblocking feature of the ATC guide makes it easy to lock off one climber and get that hand free (but I guess you'd want to make sure they stopped climbing, to avoid slack).
Mar
10
comment How to top belay 2 climbers at the same time on multi-pitch climb?
I don't quite follow the first paragraph. It seems to be responding to something that wasn't actually the question that was asked. I don't see anywhere in the question that the OP refers to using the wire loop. I think the first paragraph should just be deleted.
Mar
6
comment Hiking half dome - What are the most efficient logistics for getting a campsite in little Yosemite?
Just do something else. That area is extremely heavily impacted because too many people all want to do the same hike.
Feb
25
comment How do you flavour your water on camping trips?
From the scientific information I've seen this appears to be settled science that has been known for almost a century. I don't think it's controversial among physiologists. Of course it goes against a popular belief, so people may be surprised by the facts.
Feb
24
comment How to calculate the force (kN) generated by a falling climber onto their protection?
@aaaaargZombies: I don't think anybody actually does calculations like this for practical climbing. There are too many factors that are hard to quantify, such as rock quality, the quality of the placement, and how far beyond its rated strength the piece will really go before it's torn apart. Realistically, your time is better spent reading John Long's book on climbing anchors, and reading Accidents in North American Mountaineering to find out what really goes wrong and gets people hurt or killed. The biggest issues are: (1) minimizing fall factor, and (2) getting that first "Jesus nut" in.
Feb
19
comment Delayed muscle ache after boulder session
And BTW people used to believe that DOMS was from lactic acid buildup, but that turns out to be false.
Feb
19
comment Good books to learn survival?
Excellent, canonical answer. Deep Survival is really good on decision-making, which can be much more important than technical skills.
Feb
17
comment What is the most efficient food to take a for a 12-15 day hiking trip?
@RussellSteen: Last I read there is no place in the US that does not have a potential for Giardia. Domesticated animals, including the increased popularity of hiking with dogs, over the entire US has spread this protozoa to virtually every stream in the continental US. Totally false. More info here: lightandmatter.com/article/hiking_water.html
Feb
16
comment What size dry bag is best for keeping and washing clothes?
I don't understand the question. What is a "dry bag" in this context? Why do you want to do this? What do you mean by "travelling, not hiking?"
Feb
13
comment water knot vs figure 8 follow through vs X for rock climbing anchor - What is easiest to untie?
This application is the only reason I know the water knot. When there's a totally, totally standard knot for a certain application, I would need a heck of a good reason to use some other knot.