Chart Sack lets you navigate on any chart of your choice. You can download a topographic map from the Internet, scan a paper map, or even draw one yourself. The only requirements for the charts are that they are to scale, and are in a JPEG, BMP, GIF, or PNG file format.

Quick Start

The video here shows how to tag, and then navigate on a chart.

  1. You must be connected to Internet to tag a chart, but once it is tagged, you can navigate on it without a need for Internet connection.
  2. Place the chart you want to navigate on in the Download folder of your device (phone, tablet). The easiest way is to just download a map from the Internet using the browser.
  3. In the app’s top left menu, select “Load Chart”, then click on “Browse” to locate the chart, then click on it to load it.
  4. When the chart is loaded, it is ready to view in the “Navigate” screen in the app’s top left menu. If the chart is visible, you can start the tagging process to navigate on it.
  5. In the app’s top left menu, select “Tag Chart”.
  6. Move the centre of the red cross hair on top of a well known point, then press the tag button in the bottom right. Type the name of the point, then select one of the presented options that accurately represents that point.
  7. Repeat the process in the above step to tag one more point, diagonally well away from the first point.
  8. In the app’s top left menu, select “Navigate”, then press the “Find” button in the bottom right, then enter and select a point on the chart. If the red cross hair appears correctly on that point, you have correctly tagged the chart, and it is ready for navigation
  9. If the chart is not correctly tagged, repeat the tagging process, as described above.


  • When selecting a point during tagging, make sure that point is well defined. A well defined point can be a geological feature like “Old Faithful”, or “Mount Washington”.
  • If you know the latitude and longitude of the point being tagged, you can simply enter it as latitude,longitude (example 42.4222,-72.443).
  • When the GPS is locked, and the chart is correctly tagged, pressing the middle Home button in the “Navigate” screen will place your current position under the cross hair centre.
  • All the points that you find and select will be automatically stored in the app for future use. These points will be available regardless of Internet connectivity.
  • Charts used must be to-scale and should use WGS84 projection.