This does nothing
how do you tranform the coords of the waypoints?
MapSource will export a tab delimited text file where the coordinate format is the one chosen by the user. The format is set under Edit>Preferences>Position. Set the correct Datum and Grid and the WGS84 coordinates will be converted to that Datum and Format. BaseCamp will only export WGS84 Lat/Lon in decimal format.
You should be able to copy waypoints and paste directly into MapSource. If this is not working, export a gpx file from BaseCamp in open with MapSource.
If the Datum you need is not present in the MapSource list, you will need to create a User Datum. If the Grid format is not found in the list you may be out of luck. The User Grid option only supports a Transverse Mercator projection where the Latitude of Origin cannot be changed from 0 degrees
For all intense and purposes it is a UTM grid if you supply the a Scale Factor of 0.9996, False Easting of 500,000, False Northing of 0 for the northern hemisphere or 10,000,000 for the southern hemisphere and the appropriate value for the Central Meridian.
As for the Datum transformation, it appears that both programs use the Molodensky method.
thanks mate that sorted me out! I'll be cheeky and ask you another question - whats the best way to get gpx files into and out of QGIS?
I don't have any experience with QGIS or any other GIS applications. If I were to guess, I would try to bring a GPX file in as a layer. By requirement, a GPX file must use decimal Lat/Lon coordinates and WGS84 Datum.
I would assume that the app would automatically convert GPX coordinate reference system to that of the base layer of a project. For example, if the OP started a project with a map based on a UTM projection and the AGD66 datum, then added a layer of data with Lat/Lon coordinates in the WGS84 datum the layer data would be converted to that of the base map automatically.
Similarly, I would expect that the GPX data could be exported to a different file format that would support an alternative coordinate reference system.
Unless someone with QGIS experience chimes in, try looking for QGIS tutorials on YouTube starting with the Basics or Beginner ones.