Originally Posted by Erin
If you copy waypoints from one programme to another or chart to GPS, watch out that you use the same datum. A waypoint on a GPS usually at WGS84 is not going to be in the same place when plotted on a chart at ED50.
Yes, that's true. The RYA program uses WGS84, the position of your cross hair on the chart is quoted in that. So, if you set a waypoint on the RYA electronic chart one cable from a rock, say, your GPS will take you right to that place. If you take the co ordinates of that position from the equivalent paper chart, they will not be the same. The amount of correction to apply is marked under the title of the paper chart.
I found this confusing at first, being new to GPS navigation, but with the RYA program there is no need to convert anything, the position of your cross hair cursor is shown in WGS84, irrespective of the chart's datum. Mmm, better stop trying - I'm confusing myself again :-).
I didn't really believe this (or couldn't understand the explanation in the program help, which seems to suggest otherwise). However, having plotted waypoints in the RYA program, entered the co-ordinates it gave me, without correction, into my Garmin 126, and driven my boat there, I can say they were exactly right (to within a yard or two anyway.)