Please don't call me a caveman, but

[KingSlug]

Please don't call me a caveman, but does anyone here used old school nav tools? I was a C130 navigator so I am a little crazy about nav. Now I have a GPS, but I love old school tech. These are my backups: Mag compass, Abrams sun compass, Astro Compass and my RAF bubble sextant.

First line: magnetic compass good in most situtations easy to use. Drawback around metal deposits/objects.

Second line: Abrams or Bagnold sun compasses or Astro compass good day or night. Drawbacks: They can only be used when the sky is clear, adjustments and almanac.

Third line: Bubble Sextants, use day or night, gives direction and position. Drawbacks: same as second line tools.

What tools do you use for navigation besides GPS?

 

[DaveInDenver]

Please don't call me a caveman, but does anyone here used old school nav tools?

What tools do you use for navigation besides GPS?

Besides GPS? I don't have GPS and I'm guessing I'm about the only one here who doesn't. Am I missing something? I dunno, probably. None-the-less, my navigation tools are a case full of maps, a compass, inclinometer, protractor, pencil and my brain. I'm sure as time goes on the computer between the ears will fail me, but so far in 35 years I've done OK.

 

[bigreen505]

Besides GPS? I don't have GPS and I'm guessing I'm about the only one here who doesn't. Am I missing something?

Yeah, when people here plan a trip and give the right GPS coordinates, but the wrong directions, it is late and dark so a map is of minimal value since you don't really know where you are. I haven't used my GPS much in the backcountry yet, but it is really nice to figure out where the heck I am.

 

[kcowyo]

Count me an another who doesn't use his GPS as a primary souce for navigation.

For me it's one of those things that you must use regularly to be proficient with and I just don't use mine often enough. It does make a great paperweight to lay on my maps when rolling with the windows down. And I really like gadgets and gizmos, I just never warmed up to the GPS as it always felt like one more thing to keep an eye on when on/off the trail.

I guess I just prefer looking at big, colorful maps all laid out to plan where I want to go next. :088:

 

[devinsixtyseven]

I've been using various maps (no two maps seem to show the same features the same way), directions and now satellite photos for a while.

I'd actually like to get some cool old-school goodies, or the new-school versions.

How would you go about finding your latitude and longitude the old-school way? Care to share? I'd rather learn how to do that, have the tools and give it a shot, and have a backup digital solution to make sure I'm right .

 

[RoundOut]

My Dad was a career Air Force Navigator. I have all of his nav tools from his flight bag at home. My Mom wanted to chunk them or sell them and I thought that was ridiculous, so I bogarted the whole bunch. There are some pretty cool slide rules, dial instruments, dividers, and such, but I don't think there is a sextant in the box. I'll have to check.

Your question though, was do we use them? I have a USB and Bluetooth GPS and just finished installing a laptop mount so I can use it with my computer for navigation, but have yet to use it off road. I also have a compass on my rear-view mirror, which is accurate to about +/- 45 degrees (read: not much use). I also have the standard orienteering stuff that we teach the kids in Scouts. Although I am not an "expert" at this, I can find a course and get us there the old fashioned way, provided we are not on endless flat prarie with no landmarks or topography.
:sunflower

 

[kcowyo]

My Mom wanted to chunk them or sell them and I thought that was rediculous, so I bogarted the whole bunch.

Great word!

Wrong context *cough-cough* :ylsmoke:

 

[bigreen505]

How would you go about finding your latitude and longitude the old-school way? Care to share? I'd rather learn how to do that, have the tools and give it a shot, and have a backup digital solution to make sure I'm right .

Well, if you have the right maps and you know where you are -- meaning you can look at surrounding geological features (peaks, valleys, roads, lakes, streams, etc.) -- you can simply trace the lat from the X-axis margin of the map and the long from the Y-axis. Sounds simple enough, but the trick is in the first part. That is why I like GPS so much, it is easier to translate your coordinates to where you are on the map than the other way around.

Another way to go is look for the USGS brass slugs in the ground on mountain tops. They will have lat/long engraved on them and will correspond to a X on 7.5 minute maps.

 

[DaveInDenver]

How would you go about finding your latitude and longitude the old-school way? Care to share? I'd rather learn how to do that, have the tools and give it a shot, and have a backup digital solution to make sure I'm right .

Triangulation with features. First, find a couple of prominent features. Say 3 at 120 degree intervals, but a couple of distinctive summits, geologic features, maybe well defined man-made things like airports or something would work. Take a bearing on each and note the reading. Put the compass on the map, aligning it so that the compass' meridian lines (IIRC, these are white on my Brunton face) are pointed north (alignment to the map will require the use of the grid lines drawn parallel to north). Mark the bearing line from the feature back to your position with the pencil. Do this for all the features you've taken bearings for and the point where the lines intersect is your position. Then read the LAT and LONG from the map.

 

[KingSlug]

Some old school tools....

I grew up loving to watching reruns of Rat Patrol, thats watch originally got me hooked on sun compasses.
http://perso.orange.fr/cadrans-solaires/navigation/navig_uk.html

Here is a site about navigating in the Sahara:
http://www.pisces-press.com/C-Nav/
http://www.pisces-press.com/C-Nav/instruments.htm

I think any book on celestial navigation is a good start. I like looking at stars so its a good match for me. With a bubble sextant you can get down to 1nm of your position, its probably not good for geocaching.

Of course one should carry a mag compass and a set of Plathe Star Charts. I have an PBY compass I am going to mount in my Ambulance it was a NOS boxed spare in the PBY Catalina my dad bought. Next, I would suggest buying or making a sun compass or picking up a used Astro compass up off ebay. Most could stop there if you like, but a surplus bubble sextant can be had for under $100 and the navigational training you develop using it is almost invaluable. If you find a celestial theodolite please tell me, I have a 1960s german model that cost $3k that I use mostly for stars but would like a lighter model.

Here is an Astro Lab manual:
http://www.pge.com/education_training/pec/tool_lending/application_notes/astro_compass.pdf
Here is a bubble sextant like I have:
http://www.users.bigpond.com/bgrobler/sextant/sextant.html
Here is a place to get nav tools:
http://celestaire.com/catalog/index.html

Latitude and Longitude is most often found by sighting the sun, stars and moon. It would take alot to explain it here.

RO, I was an enlisted Marine Navigator. Besides nav gear I like to collect slide rules and dials. If you ever might want to sell or learn how to use them I could get you the instructions. I am especially interested in 1930-1960s dead reckoning slide rules.

I have nothing against maps, I have a mint invested in them. But in the Gobi, Sahara, Tunda, at sea or in Kansas there just isnt enough topo to go off.

Do you guys really use your GPS, or is it just a toy that spits out numbers?

 

[Pskhaat]

A lot of companies' icons and logos have the compass rose of some sort on them. I'm wondering when a GPS unit/display will replace those companies' logos?

 

[Martinjmpr]

Re: Finding your position w/o GPS

Dave in Denver describes the process of Resection (determining your position from looking at two other known positions.) A simpler way, and probably more appropriate considering that we often travel on known roads or near rivers or other linear features (like RR tracks) is modified resection. Modified resection uses the intersection of an azimuth with a linear terrain feature.

So, let's say you're on County Road 58, which is marked on your map. You shoot an azimuth to Sunlight Peak, which gives you an azimuth of 118 degrees. Since 118 is less than 180, you add 180 degrees to get your back azimuth of 298 degrees. On your map, center your compass or protractor at Sunlight Peak and trace an azimuth of 298 degees. The point where this line intersects with County Road 58 is your position.

However, it's important to know the declination of your area, which is the difference between magnetic north and grid (true) north.* Most military or USGS maps will tell you what your declination is, though you will also have to make sure the map is current (declination changes as the magnetic pole moves.) There are also generic declination diagrams that you can use that will show you, with a margin of error, approximately what the declination of a given area is. This is usually "close enough" for the purposes of determining where you are.

You always want to figure in the declination before you draw your back azimuth, otherwise it will be off. For example, let's say the declination in your area is such that True North is 15 degrees west of Magnetic North. [Note: I can't remember if that's an "east declination" or a "west declination."] So, in the example above, you shoot an azimuth to Sunlight Peak and it comes out to 118 degrees. Then you subtract 15 degrees (that is, you go 15 degrees west) and come up with 103 degrees. Then you add your 180 degrees to get your back azimuth of 283 degrees. Starting at Sunlight Peak you draw a back azimuth of 283 degrees until the line intersects with County Road 58 and there you are.

Note that you can do this with any readily identifiable linear feature such as a road, a river, a railroad, or a power line, provided that it shows up on your map. Obviously, the trick here is to make sure you know what linear feature you are on, and to know what terrain feature you are taking your azimuth from.

I love my GPS, but I'll be the first to say that a GPS is a good supplement to a map, but cannot completely replace a map for a number of reasons (not the least of which is that a map will never need batteries.) :ylsmoke:


Martin

[Edit: Changed my declination from "15 degrees East" to "15 degrees West" so it would make sense. Otherwise my directions would be off!]


*No doubt someone is going to point out that True North and Grid North are not identical. True, but unless you're calling in an artillery or air strike, they are for all practical purposes the same.

 

[DaveInDenver]

However, it's important to know the declination of your area, which is the difference between magnetic north and grid (true) north.* Most military or USGS maps will tell you what your declination is, though you will also have to make sure the map is current (declination changes as the magnetic pole moves.)

*No doubt someone is going to point out that True North and Grid North are not identical. True, but unless you're calling in an artillery or air strike, they are for all practical purposes the same.

No comment on True North, but magnetic declination is something I forgot to mention. Here in CO it's about 9 degrees, 20 minutes E. Some places there is no declination, others it's huge. Where I first learn orienteering, in St. Louis, MO, there is basically zero declination. However, in Portland, ME, the declination is 16 degrees W and Anchorage, AK, it's 19 degrees E. There is significant correction you'll need to be aware of. Good thing is declination is printed on the map you're using.

 

[devinsixtyseven]

Honestly, looking at features and looking at a map is about what I do now, but without the compass . Thanks for the quick tutorial, I'll be giving it a shot to see if what I get from a compass and topo is the same ballpark as the GPS coords.

What I was really interested in is what KingSlug was talking about. When there are no features, how do you know where you are--or what if all the features look the same? The only reference is sun/moon/stars. That's what I want to learn. I'll look in to the links, thanks .

I only have experience referencing general geography to lat/lon coords. Turning minutes/seconds/tenths to distance on the ground, I haven't yet since I haven't got a GPS receiver...but it'll be interesting to try Dave's & Martin's instructions in a couple weeks.

1 nm = 1 arcminute anywhere on the surface of the Earth. So, if your measuring equipment is reading in minutes.decimals, a tenth is 600 feet, a hundredth is 60 feet, and a thousandth is 6 feet.

That also means that if you're using DMS (what I am used to), one second is 100 feet, and a tenth is 10 feet, which is the most accuracy I would reasonably expect from at least four birds and P code. More reasonably, with the C/A code, I'd look for fifty feet around me, which IMHO is not accurate enough if you're trying to figure out which of two or three nearby turns is the right one--so it's back to the maps, and the GPS remains a coarse positioning tool.

Unless, of course, the C/A code is still turned up to the accuracy of the P code, since I don't have a decoder in my back pocket for the P(Y) code. Then, I'd look for ten feet or so. Bronze USGS markers are a great resource, the trick is finding them. Best luck is to find the markers in less-developed areas...we tried finding quite a few back when they first turned off S/A, markers in more urban areas had usually been long gone. We found ours on the outskirts of town, one was in a ditch covered by an old hubcap, another was in an open space, etc...then you can test the accuracy of your unit with a given number of birds and see how well you can trust the precision listed on the unit.

I've just never tried turning all that stuff in to boots on the ground measurements...

-Sean

*edit* At some point in the future, would some of you Denver guys be willing/interested to meet up somewhere in the backcountry with a couple maps and measuring devices and helping a relative navigation noob like me learn how to do this?

 

[BajaTaco]

Prior to the acquisition of a GPSR, I used maps and compass and varying methods as described in this thread (triagulation, modified resection).

More than anything, I have always used (and still do) paper maps combined with simple visual observation to figure out a rough estimate of where I am on a map. I would say that this type of "seat of the pants" navigation is the most I have ever used. Obviously, it gets tougher in heavy forest/tree cover to determine visual landmarks. But really, just keeping track of my movement and looking around me provides pretty good results and allows to get where I need to go. If in a vehicle, I would always make mileage notes (using the odometer or trip meter) zero'ing-out at known points on the map, and then use a paper scrap or something with pencil marks on it as a scale to estimate my position along the road on whatever map I happened to be using. If on foot, I would use trail intersections and known landmarks, and keep an eye on time to estimate my speed and therefore use that to help judge distance of travel on the map. If I have an altimeter with me (like on my old watch) then I could also use elevation as a point of reference. Definitely not as precise as laying down data on a map, but I have never been lost... for very long anyway I will say that navigating in the desert (unless it is endless dunes or prairie) is a piece of cake compared to the jungle or a dense forest.

Just for the fun of the topic we are discussing here, I will mention that when I was living out of my truck in Baja I practiced with a method to navigate my way out and back from an originating point without using a map at all. I first did it in a mangrove forest on foot, so that I couldn't easily track my position visually. For this method, you use positive azimuth and travel vectors. It is cumbersome to monitor the measurements and keep track of the data. You really have to pay attention to every leg of your travel and every change in direction and record it. But, it does work.