These are the steps I took:
- Digitise the chart. Because I only have an A4 scanner I had to take 6 overlapping scans of the chart to cover the entire chart area. This was done using my little HP scanner at home, but you could potentially even photograph the chart
- Merge Images. Using Adobe Photomerge, I combined the 6 scanned images into one mega highres image of the chart. You can also use free software like Hugin or PTGUI.
- Geo-reference Image. In order to be able to see my location on the image with GPS software I geo-referenced the image and created a GeoTIFF using the open source QGIS software and following this tutorial. https://www.qgistutorials.com/en/docs/3 ... asics.html
- Import Map to Phone or Tablet. Install the free Avenza Maps app onto your device and then select "Import Map". Choose the GeoTiFF you created in the last step and import it.