Activity for Mark‭

Type	On...	Excerpt	Status	Date
Question	—	Where can I test an emergency whistle? I've just 3d-printed what's supposed to be an ear-shatteringly loud emergency whistle (120 dB at one meter). However, it's apparently somewhat sensitive to printing conditions, because some people report their whistle doesn't make any sound at all when blown. Clearly, I need to test mine before I e... (more)	—	almost 6 years ago
Answer	—	A: Can I sleep in my canoe with it adrift on a commonly used lake? For the specific question of drifting on the Great Lakes, doing so is effectively suicide. First, there's the matter of traffic. The Great Lakes are a major shipping lane, with upwards of a hundred lake freighters, numerous ocean-going freighters, barge traffic, and other ships traveling at all tim... (more)	—	about 6 years ago
Answer	—	A: How much should I worry/care about the "Known to the State of California" warnings on fuel canisters? Most of the time, the "Known to the State of California" warning is an incantation to ward off lawyers. That's not true for fuel. White gas/Coleman fuel/whatever-it's-called has significant amounts of benzene, a known carcinogen, in it, as does kerosene; other hydrocarbon fuels will have trace amou... (more)	—	over 6 years ago
Answer	—	A: Are statistics about the frequency of crime actually useful in determining how safe a trail is? The crime rate on most trails is 0, due to the very low frequency of use. The trails that have had a crime committed on them tend to have a very high crime rate, again due to the low frequency of use. There are only a few trails that have high enough usage for the crime rate statistics to be domina... (more)	—	over 6 years ago
Answer	—	A: Can any automotive fluids be made safe to drink? There are three fluids in your car that contain water: the battery electrolyte, the washer fluid, and the coolant. Everything else is hydrocarbon-based, and in a properly-functioning car, contains no water. In the battery, the electrolyte is a mix of sulfuric acid and distilled water. A modern se... (more)	—	over 6 years ago
Answer	—	A: Should overweight people ever climb? It's called the "mountain climber's weight loss program": eat everything you want, and climb two mountains a week. Serious rock climbers aren't fat because they can't eat enough to get fat. Climbing a mountain, or spending a day bouncing up and down a cliff, can easily burn 10,000 calories. No mat... (more)	—	about 7 years ago
Answer	—	A: Does fordable by 4WD imply fordable on foot? The presence of a ford in a river is a local condition: it's a point in the flow where the river has leveled out, producing a wide, slow, shallow flow. In addition, a ford generally has a hard bottom, either naturally or through "improvement" with imported gravel. The presence of a ford at one poin... (more)	—	over 7 years ago
Answer	—	A: What must be causing a decrease in sparrows and an increase in pigeons in my town? At a guess? A change in architecture. Pigeons favor cliff ledges as nesting sites; they'll happily build nests on window ledges as a substitute for natural cliffs. Sparrows favor cavities: tree hollows, the eaves of roofs, and other somewhat-enclosed areas. If there's been a trend of replacing tr... (more)	—	over 7 years ago
Answer	—	A: How can one know where to throw one's spear when spearfishing? The easy technique is to simply hold the spear in your hand with the tip under the water and stab the fish. Once your spear enters the water, refraction has identical effects on your view of the spear point and your view of the fish, so you can easily guide it to where you want. Throwing a spear to... (more)	—	over 7 years ago
Question	—	Disposing of live ammunition While out hiking today, I came across a spot where someone had fired off a couple dozen shotgun shells, then left the spent cartridges lying around. Dealing with those was simple (put them in my trash bag for later disposal), but there were also four discarded live shells. What's the best way of de... (more)	—	about 8 years ago
Answer	—	A: How would one assess the safety of a wooden bridge? Look under the bridge for cracked or rotted beams -- in particular, cracking in the middle of the bridge, or rotten wood at the ends. If the bridge is more sophisticated than a deck nailed on top of a couple of logs, look at the joints for obvious damage. Stand on one end of the bridge and shift you... (more)	—	about 8 years ago
Answer	—	A: What to look for on the site of a geocache? Since you describe it as "near your residence", it's probably what is known as an "urban micro": a small, camouflaged container attached to something like a street sign or a lamp post. (more)	—	about 8 years ago
Answer	—	A: Am I packing too much for a 2-3 day hike in the forests? For the most part, your list looks reasonable for traditional (ie. non-ultralight) backpacking. The most important thing now is to get the pack fitted and balanced properly, and then get used to moving around while carrying the weight. 20kg hanging off your back will change your balance, so you nee... (more)	—	over 8 years ago
Answer	—	A: What is the best time of day to view Bison in Oklahoma? I'm not familiar with the Wichita refuge; my bison experience comes from the Yellowstone area. That said, I would never describe bison as being particularly "active": they spend most of their time either resting or grazing, with the herd slowly moving on to uneaten patches of grass. If you want to ... (more)	—	almost 9 years ago
Answer	—	A: What to consider while walking around a Geyser The big risk in geyser basins is that you can't see what's going on underground. There are often latent hot springs or fumaroles: areas where hot water or steam has eroded the ground almost all the way to the surface. If you step on one of these areas, you may break through the crust and find yours... (more)	—	almost 9 years ago
Answer	—	A: Water filters - why sand and rocks? His filter has basically two stages: A series of mechanical filters (coarse rocks, fine rocks, coarse sand, fine sand) to remove macroscopic contaminants (eg. dirt) from the water. By using several different sizes of material, he's extending the life of the filter: each layer will tend to block ma... (more)	—	about 9 years ago
Answer	—	A: What is the longest stretch of bike trail that parallels a navigable river in the US? For reasonable values of "trail", "parallels", "navigable", and "river", the Washington and Idaho Centennial Trails run 59 miles from Higgens Point on Lake Coeur d'Alene to Sontag Park on the Spokane River; an 11-mile extension to the Long Lake area is planned for the near future for a total of 70 mi... (more)	—	about 9 years ago
Answer	—	A: Is it feasible to hike Zion and Bryce in Utah in mid-May? Zion has only one unpaved road you're likely to want to drive on: a one-mile stretch of the Lava Point road. That road is marked on the map as "impassible when wet", which I suspect means an SUV won't do any better than a sedan in bad weather; it's not marked as high-clearance, so a sedan will do ju... (more)	—	over 9 years ago
Answer	—	A: Do mountains regularly (for a mountain) change height? Some mountains change height at a surprisingly fast rate. For example, the magma chamber beneath the Yellowstone caldera is currently inflating. This is causing some of the nearby mountains to grow by as much as an inch or two per year. (more)	—	about 10 years ago
Answer	—	A: What batteries would make sense to power 12v devices (e.g. blankets, lights) for camping? Some back-of-the-envelope calculations: 12 volts 4 amps = 48 watts 8 hours = 384 watt-hours. That's the minimum battery capacity you'll need to power this for a night. The Goal Zero Sherpa 50 you propose to use will power it for about an hour, give or take efficiency losses. To power the blanke... (more)	—	about 10 years ago
Answer	—	A: Is burying human waste always the lowest-impact solution? If you were the only visitor to the area, the lowest impact would be to defecate on the surface and leave it. Few animals bury their waste, so natural disposal has evolved around dealing with surface waste. However, you aren't the only visitor. Burial slows decomposition and disrupts the soil, but... (more)	—	about 10 years ago
Answer	—	A: Do barrel style root cellars get colder the deeper you dig them? For any reasonable depth (ie. something you'd be willing to dig without specialized machinery), a deeper hole makes for a more stable temperature. The extra mass of soil surrounding your cellar acts to average out temperature changes: shallow burial averages out day-night shifts, while deeper averag... (more)	—	over 10 years ago
Answer	—	A: Is it safe to be in a vehicle during lightning/thunderstorms? If your vehicle has a closed metallic structure, you are definitely safer inside than out: if lightning strikes your vehicle, or near your vehicle, the metal will conduct the electricity away from you. The protection is almost as good as if you were inside a building with a lightning rod. If you ar... (more)	—	over 10 years ago
Answer	—	A: What format should I use to report my location to emergency responders? I'd give my position in terms of landmarks ("I'm about five miles up Independence Creek; look for the silver emergency blanket draped over the bushes"). If I had a GPS, I'd also give coordinates in whatever units it displays. If you've ever gone geocaching, you'll know that while coordinates are pr... (more)	—	over 10 years ago
Answer	—	A: What are the key differences between Mountaineering and Rock Climbing? According to my father (a self-identified mountaineer), the difference is as follows: A rock climber encounters a cliff on a mountainside. He spends some time studying it, finds the most interesting route, climbs up and back down, and calls it a day. A mountaineer encounters a cliff on a mountains... (more)	—	over 10 years ago
Answer	—	A: Depth Perception in the Mountains Yes, and yes. According to people I've talked to who work at the Grand Canyon, visitors from the western United States (especially the rural parts of the Mountain West) find the canyon more impressive than those from the east (especially the urban east). The prevailing theory is that they've learne... (more)	—	over 10 years ago
Answer	—	A: Logic behind hikers yielding to horses? In the Grand Canyon, it's because it's easier for a human to get off the trail than it is for a mule. I suspect the same reasoning applies in most places. (more)	—	over 10 years ago
Answer	—	A: How do you determine how long a hike will take? Naismith's rule is a good starting point, but it doesn't really cover unusual trail conditions. My rule of thumb is to convert distance, elevation, and trail condition to "equivalent miles": Each mile is a mile. Each 500 feet of elevation gain is a mile. Distance traveled on snow or loose rock co... (more)	—	over 10 years ago
Answer	—	A: What hikes are must-do at the Grand Canyon north rim? This really depends on what sort of condition you're in. For example, if you're a trail-runner in good shape who's used to high altitudes, the 28 miles from the rim to Phantom Ranch and back would be a reasonable day trip; if you're a sedentary lowlander, even a flat one-mile hike might be hard. Th... (more)	—	over 10 years ago
Answer	—	A: Color vision deficiency a dead end for mountaineering career, as an athlete? It depends on the nature of the deficiency. The most common form, red-green colorblindness, isn't a problem: I'm not aware of any situation where color coding is used to convey safety-critical information. On the other hand, if you've got rod monochromacy, climbing mountains is probably a bad idea.... (more)	—	over 10 years ago