Author Topic: what do you do when you don't have good maps?  (Read 4010 times)

azimuth360

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what do you do when you don't have good maps?
« on: September 13, 2012, 02:37:56 AM »
In the USA and Britain we are blessed with excellent topo maps of our countries.  How do you change your nav system when you operate in an area with poor maps?

I have some friends who are missionaries to Africa and are home on a break.  They want me to teach them some landnav but a number of methods depend on a good map, and you can't always get one for a given section of African bush.
"Do nothing in haste; look well to each step; and from the beginning think what may be the end." -- Edward Whymper

Skills4Survival

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Re: what do you do when you don't have good maps?
« Reply #1 on: September 13, 2012, 11:02:40 AM »
mmm, what would a bad map mean? The less features you have, the less important the map becomes (that is a bold statement, I know). Features are always there to some extend. But, how would 300km2 of African Savanna look like on a map (to be honest I have never seen that). To some extend you will have big features like rivers, hills, mountain ranges, vegetation coverage, roads. You can almost always find a map, even when scales like 1:1000.000 or smaller.  You will have to work with dead reckoning, measuring distance and direction, plotting where you go. So, it is more on navigation skills then the map only. I would take two GPS devices in such area's and a small scale overview map, program the signification freastures into both devices, making sure you can correlate map with gps postion. But, there are a few people here who actually have experience with this.
Ivo

walter.schuit

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Re: what do you do when you don't have good maps?
« Reply #2 on: September 13, 2012, 09:11:03 PM »
If you can look farther away and see some mountains, it will help to make (digital) pictures of them and give them names (if they don´t have them), so you can talk about them, memorize them. And if you have a small scale map you should identify them on the map, using your compass to orient the map and so  combine the terrain pictures with the distant mountain forms. Comparing the digital pictures of mountains with their image in the field has a learning effect: you will sooner be able to recognize the distant forms without looking at your camera screen. And then, of course, triangulation would be a help and a precision compass, like Suunto KB-14. And in a vehicle use your trip odometer for measuring distances.

Skills4Survival

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Re: what do you do when you don't have good maps?
« Reply #3 on: September 14, 2012, 10:11:37 AM »
just got another idea, use binoculars with a build in compass. The ulitmate navigation manual I think speaks of a Steiner Commander (do not know which version has the compass in it). I think that piece of equipment might come in handy on vast planes.
Ivo

Callum

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Re: what do you do when you don't have good maps?
« Reply #4 on: September 14, 2012, 06:23:10 PM »
What about Google Earth images and creating waypoints and routes on a handheld satnav, to follow, as reference and possible escape routes?

walter.schuit

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Re: what do you do when you don't have good maps?
« Reply #5 on: September 14, 2012, 08:11:53 PM »
Yes, of course: you can even print out screens from maps.google.com and glue them together, although this will cost you some time. I did this to have a different view of a piece of desert. The google maps come with shading and still have contour lines.

Brian

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Re: what do you do when you don't have good maps?
« Reply #6 on: September 15, 2012, 05:15:51 PM »
What about Google Earth images and creating waypoints and routes on a handheld satnav, to follow, as reference and possible escape routes?

Agree. 

We conducted a mock search a week ago of an area for which our 1:24,000 topo maps show precious little . . . merely contour lines and buildings . . . but which do show some non-existent roads which had been planned but never built.

(In other words, topo map features that are not present are depicted, features that are present are not depicted!)

In reality, the terrain was far more convoluted than the maps showed, and the region was crisscrossed with dozens of trails, none of which were represented on the topo maps (paper or computer-generated).

Google Earth proved to be very useful:  most of the trails showed up and one could gain a real appreciation for the contours of the terrain, much better than one could see even on a digital map with "shadow" enabled.

Using that Google Earth map, and with (Google Earth generated) coordinates defining search areas, our people were able to search effectively.

Those Google Earth maps are a good resource, sometimes even better than a standard topo map.

Lyle Brotherton

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Re: what do you do when you don't have good maps?
« Reply #7 on: September 16, 2012, 11:52:56 AM »
Azimuth360, I totally concur with everything the boys have written. On my mission to the Amazonian jungle, my mainstay maps were from Google Earth, augmented with recent aerial NASA photography to show the ever changing waterways and flood plains, and pre-marked-up with waypoints and routes.

Compass Binoculars are of limited value in these environments, unless you can gain height to see above the canopy of the forest, however in areas where there are vast plains, such as the Serengeti Plains in Africa or when I was navigating is desert environments, from crossing Lake Fryxell in the Antarctic, to the Makgadikgadi Pans in the Kalahari Desert, they are invaluable.

Environmental navigation help significantly with orientation, as sand dunes (P 212, 214 UNM) and I would also recommend stellar navigation (P60 UNM).
“Opinion is the medium between knowledge and ignorance” - Plato