This teaches a navigation skill which is of little use for the trail except in the desert or in the plains. But it's fun. It could help someone get oriented some day.
Situation: You are in Oklahoma in an area of section lines. In the distance you see a grain elevator in a known town. You are about 5 miles away. You have a map and a compass, but there are no landmarks but the grain elevator.
Problem: Describe how you would find your exact position.
Am I on a known, mapped trail? If so, take a bearing on the elevator, transfer the bearing to a line on the map (allowing for declination), and you're where the trail and the bearing intersect. (Assumes that the trail does not double back on itself, so that there would not be more than one intersection.) This seems too easy a solution, since it's just a variant of triangulation, with the trail itself serving as a landmark, which violates the conditions of the problem.
If I'm not located on another map feature (road, trail, creek, etc.), I'll need to think a bit more.
Registered: 02/23/07
Posts: 1735
Loc: California (southern)
Oklahoma doesn't have much of anything except flat open ground. (You can tell I am not an Oklahoma fan, and the area is probably better than I think it is).
Oklahoma doesn't have much of anything except flat open ground. (You can tell I am not an Oklahoma fan, and the area is probably better than I think it is).
This is a building block approach to learning how to get oriented in the desert. It's a method of triangulating off one point. Be fun for a Boy Scout project.
Registered: 02/23/03
Posts: 2124
Loc: Meadow Valley, CA
I don't carry enough aluminum to make a cap to help with receiving vibes to my brain. Wait a minute, you give us section lines and now you take them away? Duane
Registered: 02/07/07
Posts: 3917
Loc: Ozark Mountains in SW Missouri
Originally Posted By Gershon
Dryer,
Your method was much better than mine.
Now take away the section lines.
(Yes, there are grain elevators in OK.)
Well, since you can orient your map with your compass and plot a line to the elevator, you'd know your somewhere on that line. So I imagine you'd come pretty close by plotting another line using the sun at either sun up or sundown.
Well, since you can orient your map with your compass and plot a line to the elevator, you'd know your somewhere on that line. So I imagine you'd come pretty close by plotting another line using the sun at either sun up or sundown.
Bill,
What you are describing is celestial navigation. That would be tough without the stars. I think it would take 2 days and a lot of knowledge. (You'd use the stars to find the declination of the sun. Then use that to determine where the sun would set. With the combination of the north star to find latitude and the rising and the setting of the sun to find two other lines, you'd have a 3 star fix.
Ok, I drew a picture. Let's assume zero magnetic variation as that complicates matters.
Dryer had the simple solution. There is only one place where a bearing line would fit exactly between the bearin lines.
My idea was to take a bearing. Walk a mile and take another bearing. There is only one place a line a mile long in the direction you walked would fit between the two lines. Taking away the lines wouldn't make it any harder.
No sections lines? So, now we are on a flat, featureless plain, with one landmark.
You don't have the equipment to give you 'minute of arc' EXACT location. A sextant would be nice. However, you said 'about 5 miles' so at least you have a clue there.
At night: Find Polaris if the sky is clear and orient your map...or use your compass. Take a bearing and plot a course to your town with the silo. If you are within 18 miles of any other town, you'll see the sky glow. Plot bearing to what you can see, find it on the map, plot it. X marks the spot. If there is no sky glow, then you are somewhere on that line to your silo, and all you need to do is tighten up "latitude". Use your compass as an angle finder (turn it on its side like a protractor, piece of thread and a weight for a plumb-bob), and again, site Polaris. You'll then have a "loose" longitude to approximate on your map. Mark your town bearing at 5 miles...there your are! (about) All that is trickier in the daytime because you are working with the sun to to find your latitude. For hiking, finding a loose latitude can be pointless because you'll be off by miles....you can find degrees, but not minutes and seconds, with a pocket compass, anyway.
Your give away is the "about 5 miles" part. You really only need to plot a course on your map and mark it at 5 miles.
Registered: 08/16/10
Posts: 1590
Loc: San Diego CA
To get an exact position given this scenario (as I understand it), you need 2 (two) intersecting lines theoretically. Due to error/accuracy it's better to get 3 bearings. Ok though, lets just settle on 2 bearings. This is why Dryer's solution works (in a way). Although he possibly had to move to attain the second bearing (the section road), that road bearing along with the bearing to the (plotted on the map) grain tower gives you the two intersecting lines. Unless you know the distance accurately, the easiest way is 2 intersecting lines. I am assuming that you really don't know how far the town is accurately, otherwise you would know where you were anyway.
As a pilot, night dead reckoning is similar to my response to your first scenario and I use it. Towns glow and if you can shoot two points, you know your exact position. If you know your average airspeed, and when you started, or last crossed a mapped landmark, you can tell where you are with one point, but two or three are always better. Working with stars or the sun takes practice, a general astronomy knowledge, and a good clock, but that's how ships navigated prior to GPS for 250 years. Google "Harrison Clocks" for some adventure. John Harrison won the "Longitude Prize" after many years of trying to convince the Royal board on which Issac Newton sat. Also, Captain William Bligh (the Bounty) was/is considered one of the best navigators in history. It's amazing what he could do with a small boat in 1789.
Registered: 02/03/06
Posts: 6800
Loc: Gateway to Columbia Gorge
You can also take bearings at noon (standard time, not daylight saving) to find south. It may be rough, depending on your position in your time zone, but it's close enough.
None of this celestial navigation stuff is worth much for 9-10 months of the year here in the Pacific NW west of the Cascades. You might have to wait a week for a clear day or night! However, with a thin twig you can usually get a shadow to fall on a reflective surface; if you do this at noon (see above) you can locate south. I've navigated in the Rockies without a compass, but I sure wouldn't want to do that out here!
Observing which side of a tree the moss grows to find north doesn't work here either--it grows on all sides of the tree!
Edited by OregonMouse (01/06/1202:54 PM)
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May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey
IF you know the height of the grain elevator (or close to it), then you could use it to estimate how far you are from it. You would need a calculator, unless you can do trig in your head.
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I've taken a vow of poverty. To annoy me, send money.
Somebody got a "100 Best Navigation Problems" book for Christmas, didn't he?
I need to find similar problems to this one. I think I want to tackle the orienteering merit badge this year. The problem is, most of the boys are showing no interest. If I make it a game with prizes, I will at least trick a few into earning it.
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I've taken a vow of poverty. To annoy me, send money.
I think I want to tackle the orienteering merit badge this year.
Do! When I was a scout (we're talking mid 60's here), my very cool scoutmaster set up orienteering courses every campout. Instead of control points he would have a task to complete to gain the next bearing...starting a fire with one match, flint and steel, using a magnifying glass to burn through a string holding the next clue in a tree, recite the scout motto, identify tracks, etc. Parents were at every control which was hidden from view. Losers got kitchen cleanup. Winners got a small prize. Make it a challenge and they'll do it.
I think I want to tackle the orienteering merit badge this year.
Do! When I was a scout (we're talking mid 60's here), my very cool scoutmaster set up orienteering courses every campout. Instead of control points he would have a task to complete to gain the next bearing...starting a fire with one match, flint and steel, using a magnifying glass to burn through a string holding the next clue in a tree, recite the scout motto, identify tracks, etc. Parents were at every control which was hidden from view. Losers got kitchen cleanup. Winners got a small prize. Make it a challenge and they'll do it.
We used to do the same type of thing in the 60's. If you navigated to the correct card, you got to go to the next one. If you missed it and got an incorrect one, you got a task like you suggested. Build a fire, etc.
If you got too far off, you got latrine duty, kitchen duty, etc.
You can also take bearings at noon (standard time, not daylight saving) to find south. It may be rough, depending on your position in your time zone, but it's close enough.
If you want to find exactly south, then you can just put a stick level ground and trace the path of the end of the shadow in the dirt. At the point the shadow is the longest, it is pointing to true north. Note the minutes and seconds as close as possible.
Then assume a longitude on the map. It's easier to use one divisible by 15. Say 105 degrees which is where I am.
Convert minutes to seconds. Say the shadow is longest 5 minutes after the hour. So it's 300 seconds past the hour.
15*300/3600=1.25
So, I'm 1.25 degrees west of 105W or 106.25W. Now you have the longitude.
Finding the latitude can also be done if you know the date. I'll let someone else struggle through that math.
Somebody got a "100 Best Navigation Problems" book for Christmas, didn't he?
I need to find similar problems to this one. I think I want to tackle the orienteering merit badge this year. The problem is, most of the boys are showing no interest. If I make it a game with prizes, I will at least trick a few into earning it.
I didn't get a book, but it would be fun to make one in increasing difficulty that would teach all navigation.
Orienteering is a tough subject, but can be learned with a series of simple exercises. Personally, I wouldn't train anyone who had no interest. I would jump at the chance to teach someone who was interested as I'd learn, too.
It can take tons of practice.
The first thing I think I'd do is have them learn the length of their pace. This can be done easily on a football field.
Then I'd have them see how close they can come to measuring a mile on a trail. I think a 5% error is something reasonable to shoot for.
I think this demonstrates that a map and compass is about as useful for finding yourself when you're lost as a divining rod or a trained cricket - get a GPS. Jim
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These are my own opinions based on wisdom earned through many wrong decisions. Your mileage may vary.
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