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Tools/rulers Or Devices


wretsub
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Hello Everyone,

 

Are there any tools/rules or devices that will help in determining a GPS location on the Quads?

 

I would like to be able to plot a location on the map to help in determining my location before I go out and do my research.

 

Thanks for the help

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Simply set your GPS to display UTM coordinates, NAD27 Datum (for most topo maps). Topo maps generally have the UTM coordinate numbers shown along the sides of the map. And there are UTM rulers (for various map scales) available to make it easier/more accurate, but a steady hand/eye and plain straightedge is usually sufficient.

 

Clicking on the topo map link from the cache page will give you a topo map with the cache site marked on it. And www.lostoutdoors.com has a really neat mapmaker section for plotting multiple locations on both topo and aerial photo maps.

Edited by 4x4van
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Hi wretsub I am also a National Map Corps Volunteer. Welcome.

 

First, is your GPSr set to NAD83 to match a USGS Quad Map? (actually you could use WGS84 because you won't be able to see any difference).

 

I see in your profile you have Orienteering listed as one of your Hobbies, so I must assume you are quite familiar with maps in general.

 

Your Quad Map is marked in all 4 corners with Latitude and Longitude. It also has 2 1/2 Minute Lat/Long Tick Marks. But these are not very useful for what you are asking about.

 

Instead concentrate on the fully articulated UTM squares on the Map. My Map Scale is 1: 24,000 and I bet yours is too. A good quality ruler graduated to 1 millimeter increments is quite common. 1 mm on your ruler represents 24 Meters on the Map. In any direction! Because UTM is linear in any direction, it is far superior to Lat/Long for this purpose. And of course you can do UTM To Lat/Long conversions right on your GPSr very easily after you have plotted a location.

 

The top right corner of my Map is N 40° 15' W 75° 45' in Lat/Long (actually it falls slightly off the corner, but just follow along).

 

My Garmin GPSr tells me this is 18T 0436214 4455775 in UTM.

 

I want to know what the Lat/Long Coords are when I measure 10 mm South and then 20 mm West from that point.

 

at 1 : 24,000 Scale

1 mm (ruler) = 24 Meters (map)

10 mm (ruler) = 240 Meters (map)

20 mm (ruler) = 480 Meters (map)

 

4455775 - 240 = 4455535

0436214 - 480 = 0435734

 

Edit the UTM Coords on the GPSr to 18T 0435734 4455535

Change the GPSr format to Lat /Long Degrees

 

My GPSr tells me that is N 40° 14.868' W 75° 45.337'

 

Note: UTM and Lat/Long both increase in value as you head North. They both decrease in value as you head South.

 

But UTM and Lat/Long are opposites when you are calculating for East, West.

 

UTM increases heading East

Lat/Long decreases heading East

 

UTM decreases heading West

Lat/Long increases heading West

 

Got it?

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Note to 4x4van. When the OP mentioned "quads" I checked our National Map Corps area, and found he is a new volunteer.

 

There could have been a little more specific information given to help you answer his question.

 

Please review my answer in this new context, and add any comments that might apply.

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Are there any tools/rules or devices that will help in determining  a GPS location on the Quads?

 

I would like to be able to plot a location on the map to help in determining my location before I go out and do my research.

Wretsub,

 

I have used one of these map tools The Coordinator for years, even before GPSrs, to extract a coordinate from USGS topos. It works great and is under $10.

 

As others have noted, there are other ways to accomplish what you asked for, but I think this answers your direct question.

 

Good luck.

Edited by Timpat
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Hello Everyone,

 

Are there any tools/rules or devices that will help in determining a GPS location on the Quads?

 

I would like to be able to plot a location on the map to help in determining my location before I go out and do my research.

 

Thanks for the help

All excellent advice so far. For those that like calculators to do the math, a handy-dandy tool is GeoCalc.

 

Cheers, Olar

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