Navigating without a map

Yesterday, I went out in the prairie with a compass, a pencil and some paper. After meandering around for about 1/2 mile, I left an Altoid box with $10 in it under the edge of a bush.

I took my data home, did some calculations, and went back today to find it by a more direct route to the Altoid box. When I went the calculated distance, I was 14 feet from the box.

It would be a monster post if I put it all here. So I made a blog post with an overview. Hope the external link is ok.

Blog Post

That's quite detailed. I've tried the concept over a big parking lot and got close to a penny that couldn't be seen unless you were within 10 feet.
Gershon, have you ever played with a mountaineering altimeter like a Thommen Everest? I use one when hiking big elevation changes. A compass bearing to a feature, and a glance at the altimeter puts you right on the map. You have to reset the altimeter at known points on the map once in awhile to account for pressure changes but it's actually quite accurate.

Dryer,

Thanks so much for your post as it stimulated another idea and it's something I've never heard before. Deductive reckoning isn't just map and compass. It's using everything to narrow down a position.

Situation: You passed a draw and then maintained a pretty constant altitude while on a bearing of 102 MN for 817 feet. Then you find yourself at the end of a spur. The bearing up the ridge of the spur is 243 mn. You are at 7,400 feet. Where are you?

7,400 feet gives a Line of Position (LOP). The vector 102/817 rules out most of that line. The bearing up the spur nails it.

Exactly! I've also got a couple electronic altimeters...a Brunton Sherpa weather station (small, light, and feature packed) and a built in baro chip in one of my ham radio walkie talkies. I find the old school Thommen much easier to work with. No batteries and a simple turn of the bezel sets baro pressure, just like aircraft. Plus, you can watch the needle at camp for weather pressure fronts rolling in.
I also like an altimeter when hiking rolling hills in thick forest like the Ozarks. There really isn't much to take a bearing on, but an altimeter will get you close. Just another tool in the bag and a great geek toy!
Ebay is a good place to find Thommens. Picked up the Brunton off Amazon for a really good price.

Gershon, have you discovered "high speed" thumb compasses yet? They are used in competitive orienteering and are night/day different than standard compasses. Mine is a "Moscow" and holds its bearing while running. Ringtail is our local orienteering expert...maybe he'll drop by for some orienteering wisdom.

Dryer,

If I were to use an altimeter besides my GPS I think I'd want a parachuting wrist altimeter. I could set it to the starting altitude and then it would act like a VOR needle pointing the direction to the altitude I was supposed to be at.

As for a thumb compass, I've seen them in videos. I'm kind of headed in a different direction than orienteering courses. But I'd love to hear from Ringtail on techniques.

I've simplified navigation to just a compass and no map. It's a bit extreme. Anyone who attempts it should take a safety observer who is navigating with more traditional means.

It's long, so I put it in a blog.

Admittedly, it also requires keeping a lot of records. There is a way to do it in your head, but I'm still refining that.

This is a fascinating exercise, and it certainly makes one proficient with a compass. However, as a practical matter, I prefer to navigate with a map and no compass.

The only valid reason I can think of now for doing with just the compass is because it's fun.

Well, you never know when you might be equipped with only a compass, or, more likely, an inadequate map. Ever tried following a route on an aeronautical chart? Doesn't work very well....

Oldranger,

When I flew the KC-135, we used blank charts because we were simulating a wartime mission for the navigation portion of every flight. We used dead reckoning and celestial navigation. This was in the days before GPS, or even inertial navigation. Blank charts make me more comfortable.

I know I'm taking this to the ultimate extreme. But if I can do it, then normal situations won't create any stress. That's the real end goal.

If trying something like bushwacking without a map, it would really pay to have a safety observer proficient in navigating with a map. The safety observer would only comment if conditions were actually unsafe and not if you were just going off in a strange direction. There needs to be some way for the person with the compass to communicate to the observer where they are and set some tolerances. I’d say if the person with the compass was more than 500 feet from where they thought they were, the situation is too far out of tolerance to continue with the experiment.

Using Topo Explorer, I overlaid a grid with 500 foot squares. This is 154 meters. Because it’s oriented to true north, I’ll have to convert all my headings to true before making calculations. In the west, truth is greater than magnetism, so I’d add the 8.5 degrees to the bearings.



Now communication becomes real simple. With the form I’m tracking my location on, I can always say my distance north, south east and west. For instance, I’m 500 feet north and 1,500 feet east. Now the person with the map can see if it makes sense using various land features.

If there were a big discrepancy, it would be a good time to take a break and check the numbers. The most likely error is reversing a sign. No second chances though. If it were a formal evaluation, once out of tolerance, the mission is over and now you work together.

This is a hint of where I’m headed with this. The compass work is one aspect, the map work is the other. Eventually both will be done by the same person

I was using an aero chart to climb Pacacho del Diablo in Baja California. This was back in the 1960s and no "real" topo maps were classified and not available. About all the aero charts showed us was that there was a really big hill in front of us which we knew already. Still, it made for a most entertaining trip...