Topo maps and switch to NAD 83
The US Forest Service has updated the Topo maps that cover our region.
The maps we were using were last updated in 1971 and used the NAD 27 Datum. These maps use NAD 83 so you should change the Datum setting on your GPS. Using the wrong Datum can produce an error of as much as 50 meters.
There are a total of 36 maps. Printing full size (24″ x 36″) color maps would cost $30 each so we’re not going to be doing that. Instead, when we’re preparing for a mission, we will print (using a color printer at the EOC) the portion of the map we need.
Several of us have been investigating smart phone mapping applications and at this moment, Avenza Maps seems to be the best. Avenza will read these Forest Service Maps (they are in .pdf format) and display them on your smart phone much like a high end GPS. The free version of Avenza will allow you to have three maps loaded into it. The Pro version ($99/year) supports an unlimited number of maps.
There are two methods of accessing these Topo maps:
1) We’ve setup a DropBox account under userid: USJSAR@gmail.com and password “????” [eMail USJSAR@gmail.com for password]. Avenza can access the DropBox account and load maps into the application. The problem with this approach is that you will need Internet access to load a map into Avenza.
2) [iPhone] Using iTunes you can add all the maps to the application where they will then be accessible to the Avenza import function under “From iTunes File Sharing”. With this method you can have all the maps on your phone and load the ones you need while in the field.
2) [Android] Connect your phone as a USB device and copy the .pdf files to the Internal Storage of your phone. Avenza can then import the Topo maps from the Device Storage. With this method you can have all the maps on your phone and load the ones you need while in the field.
If you want to browse/print some maps, in addition to the DropBox account, they are also on your web server: http://usjsar.org/membersOnly/topomaps.htm