How come UTM ?

QALHNTR

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<font face="Tahoma">It's probably been answered somewhere else, but why the use of UTM co-ord versus d/m/s?  In one of the Carrizo Plain posts in the varmint section, UTM seems to be the favorite way.  I use Maptech TopoScout and can easily convert between the two.  Is there an advantage in the field?  Most of my maps are d/m/s.  Thanks in advance.</font>
 

Tinhorn

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I prefer to use UTM when navigating with TopoMaps from the USGS.  It's real easy (& fast) to locate your self or a point on the maps if the UTM grid is marked on them and worthwhile to learn using UTM coordinates

Some maps already have the grid marked off but on the older ones, there are blue tick marks along the border (about 1-5/8" apart) and you'lll need to use a yard stick & Pencil to connect the marks.

Briefly, Here is the way I do it but it's hard to put in words!

A UTM coordinate mite look like this:   607123     and   4388567
but you can read it like this:   7.1   and   88.6  (123 rounds off to 1 - 567 rnds off to 6 and u can ignore the 1st few numbers)

Always read the map "Right, then UP"  and there will be a grid whos value is 07  and 88, so immediately, you know u r located in that grid (a 1-5/8" square on the map).   now, go over .1 of the way to the right in that grid and up .6 of the way and just that quick, you found almost the exact location.

You can determine UTM coords on the map in about the same way, I have a business card marked off using the meters scale on the bottom of the map with the tick marks numbered.....

A little more info is here but the example map is no longer showing up....

http://www.jesseshuntingpage.com/cgi-bin/i...=3&topic=41


Give UTM a try, if you use Topo's, you'll end up using UTM

Tinhorn
 

QALHNTR

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<font face="Tahoma">Now I get it - it's just simple, decimal based Cartesian coordinate mathematics!  Thanks.  The thread and maptech link helped out.  I'll give it a try this weekend  (especially if I can sneak out to Carrizo!).</font>
 

spectr17

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As one learned Sgt. once pointed out to me in training.

"Quick genius, tell me how far in distance 1 minute 45 seconds is in Lat/Long."

I was a fan of UTM and MGRS after that.
 

ToddP

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"Quick genius, tell me how far in distance 1 minute 45 seconds is in Lat/Long."

Boy could that vary,  LOL.

Todd
 

Topclamdigger

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 I would have said: " Sarge 1 minute 45 seconds of Latitude equals 1.75 nautical miles(1degree Latitude=60 nautical miles) If the Sarge wanted to know meters, a nautical mile equals 1,852 meters, exactly. Answer: 1.75x1,852= 3,241 meters. Distance on Nautical charts is determined by the Latitude scale of the chart.
 

ToddP

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Wouldn't one unit of whatever = to one degree Latitude be smaller as you get closer to the poles since the angle gets smaller and lines converge?

I never used nautical miles so I don't have an understanding of them.

ToddP
 

Topclamdigger

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 Yes, the Latitude scale is specific to the Latitude of chart in use. The distance is relative to actual Latitude. Common Nautical charts are Mercator projections for oceans and coastal areas. As the area of the chart decreases, the importance of distortion diminishes. Above 75*N different projections may be used.
 

spectr17

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When you  have a Sgt. screaming at you in the pouring rain with a dying GI flashlight under your poncho trying to figure out how far the rally point is, counting the 100 meter grids is the easiest and quickest way to figure distance. Lat/Long you need one of them plotters to even come close plus you have to know what lat your in. KISS applies here. I count 7 grids and the quick answer is 700 meters. Fast, less error and it makes the Sgt. go yell at someone else who lost their gas mask or bolt out of their rifle.
 

Topclamdigger

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There is a Grid system on Nautical charts. Estimation of distance is about the same as using the MGRS Grid system. I've used MGRS maps when in the Army- Artillery (M109 type). The methods are equivalent "grid protractor" for MGRS maps or "Dividers" with Nautical charts. MGRS  position is determined by reading to toward the right (East) and up (North); Lat/Lon from Equator to N and Prime Meridian to W for North America. Distance for MGRS is measured on a distance scale or  1,000m grid squares. On charts distance is determined on the Latitude grid or a distance scale at the bottom of most charts.
 

spectr17

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Oops, 1,000 meter grids. You can tell it's been awhile since I plotted huh? Topclam, I've never plotted on nautical charts much but would you say that for hiking the lat long would be better if you only had just the map with no map tools with you or would the UTM work better in your opinion?

By better I mean the easier to figure and less hassle for newbies?
 

Topclamdigger

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 Without GPS or map tools, but including a compass,  hiking while using terrain reference points within a liminted area of operation; my choice would be UTM or MGRS. Using a folded piece of paper and pencil it is possible to make a Grid protractor.Note numbers on the 1000m Grid lines.Then for convenience fold the map to include the immediate area. Triangulate to terrain features to estimate position. Why is this method called DEAD RECONING???....    
 


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