Using a UTM Corner Ruler

     A UTM Corner Ruler consists of two scales at right angles to each other. UTM Corner Rulers will typically provide an additional digit of precision beyond a UTM Grid Overlay. On a 1:24,000 scale map you will be able to determine a position to within a 10m square. The trade off is that the Corner Ruler is somewhat harder to use.

     Start by placing the top right corner of the Corner Ruler on the SW corner of the UTM grid that contains the feature. The ruler edges should extend to the West and South. To find the UTM coordinates of a feature marked on your map slide the rulers North and East until the corner is on top of the feature to be measured. Read the UTM coordinate values from the starting grid lines. To locate a UTM coordinate on the map slide the ruler North and East until the desired distances are indicated at the grid lines.

     If the grid square you are using is on the edge of your map, you may need to start from a corner other than the southwestern one. You can still use the corner ruler, remember that UTM coordinate values increase from West to East and from South to North.




     If you are using an odd scaled map or if you left your UTM tools behind, you can quickly make a simple corner ruler using the scale bars on the map.

     Start with the corner of a scrap of paper. Mark off a one kilometer distance and the 100m subdivisions using the metric scale bar. Repeat this process along the other edge. Number both rules starting from the corner which would be zero.

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UTM Grid Overlay

     If you want to find your location with more precision than is available from the grid lines on the map, you will need a tool that is marked in finer divisions. One such tool is a grid overlay. The grid overlay is placed on the map with its edge aligned with the grid lines. Then the position of the mark can be determined using the tool's additional precision. Additional precision is available by either by "eyeballing" or by using a UTM Corner Ruler with finer markings. For many land navigation situations 100m precision is quite adequate. It also fits well with the 100m accuracy of civilian GPS units.




     The example shown here locates the mark to a precision of 100m. The 10,000m and 1,000m digits of the coordinate are taken from the map. Thus the coordinates 59 82 locate the 1,000 meter square containing the star. The grid overlay is placed over the grid and the 100m digit is determined. Remember to read the Easting followed by the Northing.

In 100m abbreviated format the coordinates of the are 597 821.

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Mapping Tools - PDF Documents

UTM Grid Overlays

• 1:20,000
  
• 1:24,000
  
• 1:25,000
  
• 1:48,000
  
• 1:50,000
  
• 1:62,000
  
• 1:100,000
  
• 1:125,000
  
• 1:250,000
  

UTM Rulers and Scales

• UTM Corner Ruler
  
• 1:24,000 Scale
  
• 1:25,000 Scale
  
• 1:24,000 Scale Ruler
  

Lat/Lon Rulers

• Assorted
  
• 1:24,000
  

Compass Roses

• Round
  
• Square