it stands to reason- geology, geography

It rather depends on the nature of the emergency, doesn't it? <br><br>I tend to go back to the three P's of First Aid:<br><br>1. Preserve life;<br>2. Prevent further injury;<br>3. Promote healing and recovery.<br><br>In a survival situation, my number one concern is obviously going to be staying alive - build a shelter, build a fire, find water, etc. That pretty much covers numbers one and two, I think.<br><br>Number three is more or less equivalent to getting rescued. In such a situation, I think being able to provide a reasonable estimate of latitude/longitude *might* (in rare occasions) prove to be important. If nothing else, it would keep the mind active. :-)<br><br>How do you figure out your latitude without using any math? The longitude is easy; it requires a watch and some simple arithmetic. But I don't think you could figure out your latitude without trigonometry.

Just out of curiosity, how accurate are the results obtained by a trained, fairly competent observer using this technique? My curiosity is piqued because my experience using a sextant around the Channel Islands (US) certainly explains to me why we have the number of shipwrecks there that we do..

Personally, I am mathematically challenged :O( I mention two examples of math used in the real world. First the incredible voyage of Shakelton to the whaling station after loss of HMS Endurance. His navigator made the briefest of sun shoots under horrendous conditions to make landfall. One wrong calculation and they would have missed the small island by miles. A second example were the indian pundits. Using various mathematical tricks and simple devises, information on distances and elevations of greater India were slowly gathered. Imagine learning to keep a constant pace and step, counting those steps and having them converted to accurate measures!

Yeah. Erathosthenes rules...

You could expect an error about 4 minutes for your latitude and more for your longitude. If the steps in your table are bigger it´s about half the step (17 minutes in the example of the post) if you don´t interpolate. Because the rate of growth for the shadow is zero at noon your error in getting the shortest length will be minor but you´ll have a hard time to get the time.<br>So for the original example (stranding somewhere or making a forced landing) it may be of some help. For a hiker it´s of limited use. Provided the hiker keeps track of his movement, he will know his position at least as accurately. So I´m not too surprised that some people would rather practice firemaking than this navigation method.

Well, that plus the fact that most people hate math ;-)<br><br>I agree, it would be very hard to get so badly lost on foot that you didn't know your position within, say, 20 miles. I first got interested in survival because I have a small aircraft Private Pilot's license (and I got roped into giving a talk on Wilderness Survival to a group of pilots :-) It wouldn't take much to end up 50 or more miles off course. (I read an article once about a RCAF aircrew in the 1950's who took off on a routine flight from Resolute Bay to Churchill, Manitoba. They ended up making an emergency landing in Point Barrow, Alaska - only 1654 nautical miles off course. Now that takes real navigational ingenuity. ;-)<br><br>(To put this in perspective, the main runway at Resolute Bay pointed almost directly at Churchill. All they had to do was take off, fly straight until they picked up the Churchill beacon, home in on it, and land.) The navigator apparently got Grid North and True North confused. On the Arctic charts he was using, Grid North was actually almost due East. :-0 Hence the 90 degree turn to starboard that sent them out over the Arctic Ocean.<br><br>I love this stuff :-}