Importing exporting Tracks versus datums

[MajBach]

Hi again. Yet another question I cannot find the answer to using the manuals. I am importing tracks obtained over the years from my Lowrance into my Garmin but I am wondering about the datums when viewed in Mapsource and on the GPSr using BLuecharts. My Lowrance was setup in the WGS 84 datum so tracks were recorded as such. Using G7toWin, I can easily load those tracks an send them to Mapsource. Normally, Canadian nav-charts are in the Nad 27 datum; i cannot setermine if the bluecharts are also. Regardless, do I need to change my map datum in Mapsource to Nad or leave it to WGS? The two factors to consider are they were recorded in WGS 84 but the BLuechart is in Nad 27 (assuming) or will it make a difference?

[+apersson850]

If the Lowrance works like a Garmin, then the recording of the tracks isn't dependent upon the datum setting. These positions are all stored in the same format internally. It's only when presenting the coordinates, as numerics, to the user the datum makes a difference.

 

When opening the track in Mapsource, again the datum is of no importance, as it's still an internal thing between Mapsource and the GPS. You can (perhaps) understand this if you create a point on the map in Mapsource, then change the datum Mapsource uses. If it was important, then the point would move on the map. But it does not, as the new datum is just another representation of the world.