They don't actually have shame about this.
Sunday, August 15, 2010
Thursday, June 10, 2010
Sunday, April 25, 2010
Pacing for distance determination in the field
The Colorado Mountain Club Denver had their map and compass field trip yesterday. One of the things that I liked was at the very beginning they had a 1/2 mile flat course marked off that they had the students count paces and time themselves. A pace is two steps or count every time that the same foot hits the ground. The knowledge of pacing was then used through out the rest of the day to measure various distances.
A standard pace count for a 1/2 mile is around 500, a mile is then 1,000. If one does a half mile pace it becomes very easy to measure multiples of 0.1 mile. To find how many paces a 0.1 mile is, simply take the students pace count and drop the last digit. For example my pace count for a mile is 1076, a 0.1 mile for me would be 107 paces. Sure you lose some precision, but the act of pacing over uneven ground is just an approximation.
To travel some number of feet a quick approximation of a pace is 5 ft. So what one would do is divide the distance in feet by 5. Except that is hard to do for some people and becomes hard for most when tired, cold and tracking a lot of information. So a very simple approximation is to take the distance you want to go (say 300 ft), multiply by 2 ( 600) then drop the last digit (60 paces).
These are approximations which turn out to be pretty good on flat ground. When going uphill ones paces get shorter, downhill they get longer. This was explicitly illustrated once, and accounts for a locating error one another point we found. The first I was supposed to do 216 paces, the "leaders" commented that if I get to water I have gone too far. At 168 paces I hit a T in the trail that had water next to it. The trail had been down hill and made my paces 20% longer. For the next point I was a leader. We measured the map and computed the number of paces and sent our pacer off... up hill. We got to the point were we were to go off trail and moved in at the angle that we should have. Something very interesting then happened. 80% of the group headed down hill to search for the marking tape. The point was found further up hill then we were. It was found further up hill because the pacers step length had shortened. The group didn't have an answer for why they headed down hill for the initial search. They should have simply spread out evenly.
After thinking about some of the distances that we were asked to pace into the brush, there was obviously some error in the plotting of points. I actually had a problem with that. My point was in the wrong nose of a ridge, about 100-150' too far south (solved with a quick replot), and was only caught because we had two people who had different answers.
A standard pace count for a 1/2 mile is around 500, a mile is then 1,000. If one does a half mile pace it becomes very easy to measure multiples of 0.1 mile. To find how many paces a 0.1 mile is, simply take the students pace count and drop the last digit. For example my pace count for a mile is 1076, a 0.1 mile for me would be 107 paces. Sure you lose some precision, but the act of pacing over uneven ground is just an approximation.
To travel some number of feet a quick approximation of a pace is 5 ft. So what one would do is divide the distance in feet by 5. Except that is hard to do for some people and becomes hard for most when tired, cold and tracking a lot of information. So a very simple approximation is to take the distance you want to go (say 300 ft), multiply by 2 ( 600) then drop the last digit (60 paces).
These are approximations which turn out to be pretty good on flat ground. When going uphill ones paces get shorter, downhill they get longer. This was explicitly illustrated once, and accounts for a locating error one another point we found. The first I was supposed to do 216 paces, the "leaders" commented that if I get to water I have gone too far. At 168 paces I hit a T in the trail that had water next to it. The trail had been down hill and made my paces 20% longer. For the next point I was a leader. We measured the map and computed the number of paces and sent our pacer off... up hill. We got to the point were we were to go off trail and moved in at the angle that we should have. Something very interesting then happened. 80% of the group headed down hill to search for the marking tape. The point was found further up hill then we were. It was found further up hill because the pacers step length had shortened. The group didn't have an answer for why they headed down hill for the initial search. They should have simply spread out evenly.
After thinking about some of the distances that we were asked to pace into the brush, there was obviously some error in the plotting of points. I actually had a problem with that. My point was in the wrong nose of a ridge, about 100-150' too far south (solved with a quick replot), and was only caught because we had two people who had different answers.
Sunday, April 11, 2010
Shelter Building
View from one of the shelters.
This is why we don't use survival saws. The saw broke in the middle.
The start of a classic debris shelter
Blue Sky Snow Storm
This is from a recent blue sky snow storm. What happened is snow was being generated in the mountains and blowen into the city. It first came down the canyon. This is a ejection from the canyon.
Sunday, March 21, 2010
Tuesday, February 02, 2010
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